Scientists finally know why people get more colds and flu in winter | CNN

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CNN
 — 

There’s a chill is in the air, and you all know what that means — it’s time for cold and flu season, when it seems everyone you know is suddenly sneezing, sniffling or worse. It’s almost as if those pesky cold and flu germs whirl in with the first blast of winter weather.

Yet germs are present year-round — just think back to your last summer cold. So why do people get more colds, flu and now Covid-19 when it’s chilly outside?

In what they called a “breakthrough,” scientists uncovered the biological reason we get more respiratory illnesses in winter — the cold air itself damages the immune response occurring in the nose.

“This is the first time that we have a biologic, molecular explanation regarding one factor of our innate immune response that appears to be limited by colder temperatures,” said rhinologist Dr. Zara Patel, a professor of otolaryngology and head and neck surgery at Stanford University School of Medicine in California. She was not involved in the new study.

In fact, reducing the temperature inside the nose by as little as 9 degrees Fahrenheit (5 degrees Celsius) kills nearly 50% of the billions of helpful bacteria-fighting cells and viruses in the nostrils, according to the 2022 study published in The Journal of Allergy and Clinical Immunology.

“Cold air is associated with increased viral infection because you’ve essentially lost half of your immunity just by that small drop in temperature,” said study author Dr. Benjamin Bleier, director of otolaryngology translational research at Massachusetts Eye and Ear and an associate professor at Harvard Medical School in Boston.

“it’s important to remember that these are in vitro studies, meaning that although it is using human tissue in the lab to study this immune response, it is not a study being carried out inside someone’s actual nose,” Patel said in an email. “Often the findings of in vitro studies are confirmed in vivo, but not always.”

To understand why this occurs, Bleier and his team and coauthor Mansoor Amiji, who chairs the department of pharmaceutical sciences at Northeastern University in Boston, went on a scientific detective hunt.

A respiratory virus or bacteria invades the nose, the main point of entry into the body. Immediately, the front of the nose detects the germ, well before the back of the nose is aware of the intruder, the team discovered.

At that point, cells lining the nose immediately begin creating billions of simple copies of themselves called extracellular vesicles, or EV’s.

“EV’s can’t divide like cells can, but they are like little mini versions of cells specifically designed to go and kill these viruses,” Bleier said. “EV’s act as decoys, so now when you inhale a virus, the virus sticks to these decoys instead of sticking to the cells.”

Those “Mini Me’s” are then expelled by the cells into nasal mucus (yes, snot), where they stop invading germs before they can get to their destinations and multiply.

“This is one of, if not the only part of the immune system that leaves your body to go fight the bacteria and viruses before they actually get into your body,” Bleier said.

Once created and dispersed out into nasal secretions, the billions of EV’s then start to swarm the marauding germs, Bleier said.

“It’s like if you kick a hornet’s nest, what happens? You might see a few hornets flying around, but when you kick it, all of them all fly out of the nest to attack before that animal can get into the nest itself,” he said. “That’s the way the body mops up these inhaled viruses so they can never get into the cell in the first place.”

READ MORE: Is it a cold, flu or Covid-19? A doctor helps sort it out

When under attack, the nose increases production of extracellular vesicles by 160%, the study found. There were additional differences: EV’s had many more receptors on their surface than original cells, thus boosting the virus-stopping ability of the billions of extracellular vesicles in the nose.

“Just imagine receptors as little arms that are sticking out, trying to grab on to the viral particles as you breathe them in,” Bleier said. “And we found each vesicle has up to 20 times more receptors on the surface, making them super sticky.”

Cells in the body also contain a viral killer called micro RNA, which attack invading germs. Yet EVs in the nose contained 13 times micro RNA sequences than normal cells, the study found.

So the nose comes to battle armed with some extra superpowers. But what happens to those advantages when cold weather hits?

To find out, Bleier and his team exposed four study participants to 15 minutes of 40-degree-Fahrenheit (4.4-degree-Celsius) temperatures, and then measured conditions inside their nasal cavities.

“What we found is that when you’re exposed to cold air, the temperature in your nose can drop by as much as 9 degrees Fahrenheit. And that’s enough to essentially knock out all three of those immune advantages that the nose has,” Bleier said.

In fact, that little bit of coldness in the tip of the nose was enough to take nearly 42% of the extracellular vesicles out of the fight, Bleier said.

“Similarly, you have almost half the amount of those killer micro RNA’s inside each vesicle, and you can have up to a 70% drop in the number of receptors on each vesicle, making them much less sticky,” he said.

What does that do to your ability to fight off colds, flu and Covid-19? It cuts your immune system’s ability to fight off respiratory infections by half, Bleier said.

READ MORE: Why people who qualify should get the RSV vaccine

As it turns out, the pandemic gave us exactly what we need to help fight off chilly air and keep our immunity high, Bleier said.

“Not only do masks protect you from the direct inhalation of viruses, but it’s also like wearing a sweater on your nose,” he said.

Patel agreed: “The warmer you can keep the intranasal environment, the better this innate immune defense mechanism will be able to work. Maybe yet another reason to wear masks!”

In the future, Bleier expects to see the development of topical nasal medications that build upon this scientific revelation. These new pharmaceuticals will “essentially fool the nose into thinking it has just seen a virus,” he said.

“By having that exposure, you’ll have all these extra hornets flying around in your mucous protecting you,” he added.

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Avian Flu Fast Facts | CNN



CNN
 — 

Here’s a look at avian flu.

Avian influenza, also called avian flu or bird flu, is an illness that usually affects only birds.

There are many different strains of avian flu: 16 H subtypes and 9 N subtypes. Only those labeled H5, H7 and H10 have caused deaths in humans.

The most commonly seen and most deadly form of the virus is called “Influenza A (H5N1),” or the “H5N1 virus.”

Most cases of human bird flu infections are due to contact with infected poultry or surfaces that are contaminated with infected bird excretions: saliva, nasal secretions or feces.

Symptoms of avian flu include fever, cough, sore throat and sometimes severe respiratory diseases and pneumonia.

The CDC recommends oral oseltamivir (brand name: Tamiflu), inhaled zanamivir (brand name: Relenza) and intravenous permavir (brand name: Rapivab) for the treatment of human illness associated with avian flu.

The mortality rate is close to 60% for infected humans.

Early 1900s –The avian flu is first identified in Italy.

1961 – The H5N1 strain is isolated in birds in South Africa.

December 1983 – Chickens in Pennsylvania and Virginia are exposed to the avian flu and more than five million birds are killed to stop the disease from spreading.

1997 – Eighteen people are infected by the H5N1 strain in Hong Kong, six die. These are the first documented cases of human infection. Hong Kong destroys its entire poultry population, 1.5 million birds.

1999 Two children in Hong Kong are infected by the H9N2 strain.

February 2003 – Eighty-four people in the Netherlands are affected by the H7N7 strain of the virus, one dies.

February 7, 2004 – Twelve thousand chickens are killed in Kent County, Delaware, after they are found to be infected with the H7 virus.

October 7, 2005The avian flu reaches Europe. Romanian officials quarantine a village of about 30 people after three dead ducks there test positive for bird flu.

November 12, 2005 – A one-year-old boy in Thailand tests positive for the H5N1 strain of avian influenza.

November 16, 2005 – The World Health Organization confirms two human cases of bird flu in China, including a female poultry worker who died from the H5N1 strain.

November 17, 2005 Two deaths are confirmed in Indonesia from the H5N1 strain of avian influenza.

January 1, 2006 – A Turkish teenager dies of the H5N1 strain of avian influenza in Istanbul, and later that week, two of his sisters die.

January 17, 2006 – A 15-year-old girl from northern Iraq dies after contracting bird flu.

February 20, 2006Vietnam becomes the first country to successfully contain the disease. A country is considered disease-free when no new cases are reported in 21 days.

March 12, 2006Officials in Cameroon confirm cases of the H5N1 strain. The avian flu has now reached four African countries.

March 13, 2006 – The avian flu is confirmed by officials in Myanmar.

May 11, 2006 Djibouti announces its first cases of H5N1 – several birds and one human.

December 20, 2011 – The US Department of Health and Human Services releases a statement saying that the government is urging scientific journals to omit details from research they intend to publish on the transfer of H5N1 among mammals. There is concern that the information could be misused by terrorists.

July 31, 2012Scientists announce that H3N8, a new strain of avian flu, caused the death of more than 160 baby seals in New England in 2011.

March 31, 2013 – Chinese authorities report the first human cases of infection of avian flu H7N9 to the World Health Organization. H7N9 has not previously been detected in humans.

December 6, 2013 – A 73-year-old woman infected with H10N8 dies in China, the first human fatality from this strain.

January 8, 2014 – Canadian health officials confirm that a resident from Alberta has died from H5N1 avian flu, the first case of the virus in North America. It is also the first case of H5N1 infection ever imported by a traveler into a country where the virus is not present in poultry.

April 20, 2015 – Officials say more than five million hens will be euthanized after bird flu was detected at a commercial laying facility in northwest Iowa. According to the US Department of Agriculture, close to eight million cases of bird flu have been detected in 13 states since December. Health officials say there is little to no risk for transmission to humans with respect to H5N2. No human infections with the virus have ever been detected.

January 15, 2016 – The US Department of Agriculture confirms that a commercial turkey farm in Dubois County, Indiana, has tested positive for the H7N8 strain of avian influenza.

January 24, 2017 – Britain’s Department for Environment, Food & Rural Affairs releases a statement confirming that a case of H5N8 avian flu has been detected in a flock of farmed breeding pheasants in Preston, UK. The flock is estimated to contain around 10,000 birds. The statement adds that a number of those birds have died, and the remaining live birds at the premises are being “humanely” killed because of the disease.

February 12, 2017 – A number of provinces in China have shut down their live poultry markets to prevent the spread of avian flu after a surge in the number of infections from the H7N9 strain. At least six provinces have reported human cases of H7N9 influenza this year, according to Chinese state media, Xinhua.

March 5-7, 2017 – The USDA confirms that a commercial chicken farm in Tennessee has tested positive for the H7N9 strain of avian flu, but says it is genetically different from the H7N9 lineage out of China. The 73,500-bird flock in Lincoln County will be euthanized, according to Tyson Foods.

February 14, 2018 – Hong Kong’s Centre for Health Protection announces that a 68-year-old woman has been treated for the H7N4 strain. This is the first case of this strain in a human.

June 5, 2019 – Since 2013 there have been 1,568 confirmed human cases and 616 deaths worldwide from the H7N9 strain of avian flu, according to the Food and Agriculture Organization of the United Nations.

December 2019 – The United Kingdom Department for Environment, Food & Rural Affairs confirms that a case of H5N1 avian flu has been detected at a poultry farm in Suffolk. 27,000 birds are humanely killed because of the disease.

April 9, 2020 – The USDA confirms that a commercial turkey flock in Chesterfield County, South Carolina has tested positive for the H7N3 strain of avian flu.

January 2021 – India culls tens of thousands of poultry birds after avian influenza is detected in ducks, crows and wild geese in at least a dozen locations across the country.

February 18, 2021 – Russian authorities notify WHO that they have detected H5N8 in humans. “If confirmed, this would be the first time H5N8 has infected people,” a WHO Europe spokesperson says in a statement.

June 1, 2021 – China’s National Health Commission announces the first human case of H10N3.

February 2022 – The USDA confirms that wild birds and domestic poultry in the United States have tested positive for the H5N1 strain of avian flu. By May 17, 2023, the CDC reports there are 47 states with poultry outbreaks.

April 26, 2022 – China’s National Health Commission announces the first human case of H3N8.

April 28, 2022 – The CDC announces a case of H5 bird flu has been confirmed in a man in Colorado.

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US government is testing avian flu vaccines for birds, but ending the historic outbreak isn’t that simple | CNN



CNN
 — 

The United States is facing what some experts are calling “a new era for bird flu.”

Since January 2022, the country has been battling the biggest outbreak yet of highly pathogenic avian influenza in wildlife. The virus is a major threat to commercial and backyard flocks, and it has started to show up in hundreds of mammals, including a handful of pet cats.

The risk to humans is low; there has been only one human case of this virus in the US since the outbreak began, according to the US Centers for Disease Control and Prevention, and nine cases globally, mostly among people who work with birds. The CDC says there are trials underway of vaccines that could be used to protect humans in case the virus changes and becomes more of a threat.

Separately, the US Department of Agriculture, the US National Poultry Research Center and labs at a handful of American universities have been experimenting with vaccine candidates to be used in birds.

The USDA’s Agriculture Research Service started trials of four vaccine candidates for animals in April and expects to have initial data on a single-dose vaccine available this month. A two-dose vaccine challenge study – in which animals are exposed to the virus to see how well the vaccine works – should produce results in June.

If the animal vaccines look to be protective, the USDA’s next step would be to work with manufacturers on whether it would be feasible to use them.

One manufacturer, Zoetis, announced April 5 the development of a vaccine geared toward currently circulating virus strains. The company says it would take about a year to get to the distribution stage in the US.

Vaccines are already available in other countries, including China, Egypt, Indonesia, Italy, Mexico and Vietnam, and some nations are vaccinating their commercial flocks.

However, in the United States, not all poultry experts are ready to use a vaccine, even if one becomes available – at least, not yet. Instead, their focus remains on eradicating the virus.

As of April 26, the CDC says, nearly 58.8 million poultry have been affected by avian flu since January 2022. The virus has been detected in at least 6,737 wild birds, and the number is likely to be much higher. There have been poultry outbreaks in 47 states.

Although this is the worst outbreak in history, improved biosecurity measures have vastly reduced the number of cases in the commercial sector, according to the USDA. When the outbreak began in early 2022, there were 51 detections among commercial poultry. In March 2023, there were only seven.

The USDA says close surveillance work among its Animal and Plant Health Inspection Service (APHIS) and state and industry partners led to the reduction in cases.

Generally, there ares two ways of confronting this kind of highly infectious disease in poultry, according to Rodrigo Gallardo, a professor in poultry medicine and a specialist in avian virology at the University of California, Davis.

“One of them is through vaccination action. And then the other one is through eradication,” he said.

In the United States, the latter is the approach for now, Gallardo said.

If farmers detect even a single case in a flock, they will put down the birds right away.

“The virus keeps replicating and amplifying if the birds are alive, so the only way of stopping the replication and limiting the dissemination is by depopulation,” Gallardo said.

Tom Super, the senior vice president for communications for the National Chicken Council, the national trade association for the US broiler chicken industry, said in an email to CNN that although it supports the ongoing discussions about a vaccination program, “currently we support the eradication policy of APHIS and believe that right now this is the best approach at eliminating [bird flu] in the U.S.”

The US Poultry and Egg Association said it’s “certainly a topic of discussion,” but the organization doesn’t have a position on implementing a vaccination program.

A vaccination program comes with several complications, Gallardo said. Vaccinated birds would be protected, but with this highly infectious disease, they still could shed some virus that could infect unprotected birds.

“So vaccination, in that case, creates amplification if it is not done right,” Gallardo said.

Plus, it’s difficult to detect the disease in vaccinated birds. Birds that are vaccinated don’t always show signs if they’re sick, so it would be hard to know what birds to keep separate from the others. Tests also have a hard time telling the difference between antibodies generated by vaccination and antibodies from an infection.

“If you’re not able to diagnose it, it might spread more than what it would do if you are able to diagnose it and eradicate it,” Gallardo said.

Countries that have chosen the vaccination route see more endemic strains develop, meaning the virus is never really totally wiped out.

“This is a very variable virus, and if you don’t update the vaccine that you’re applying to meet the change in the virus, then you won’t be able to completely protect the birds. Partial protection means more birds will be spreading the virus,” Gallardo said.

A vaccine has never been used against highly pathogenic avian influenza in the US, according to the USDA. The agency created a vaccine after an outbreak in 2014 and 2015, but that involved a different strain, so it wouldn’t work on the latest version of the virus.

The logistics of a vaccine like this are difficult, said Dr. Yuko Sato, an associate professor in the College of Veterinary Medicine at Iowa State University.

“You have to make sure that the new vaccine will protect against this current virus and hope that it doesn’t mutate or change so that the vaccine will continue to be protective,” Sato said.

“The vaccine is not a silver bullet. This is not going to prevent infection of the birds, so in order to have an exit strategy as the country, you would have to make sure that if you vaccinate, if you still have positive birds, you have to be able to make sure that you could stamp out the virus. Otherwise, we’ll never be looking at eradicating the virus from the United States.”

Another concern: Birds are a big business in the US.

The US has the largest poultry industry in the world, with 294,000 poultry farms. The market size for chicken and turkey meat production alone for 2023 is projected to generate $57.8 billion, according to market analysis firm IbisWorld.

Bird flu has hurt business in the US, but it could do so in a bigger way if the nation vaccinates poultry, according to the National Chicken Council.

“The National Chicken Council does not support the use of a vaccine for [bird flu] for a variety of reasons – the primary one being trade. Most countries, including the US, do not recognize countries that vaccinate as free of [bird flu] due to concerns that vaccines can mask the presence of the disease. Therefore, they do not accept exports from countries that do vaccinate,” Super wrote in his email.

The US broiler industry is the second largest exporter of chicken in the world. It exports about 18% of the chicken meat produced in the United States, valued at more than $5 billion annually.

“If we start vaccinating for [bird flu] in the U.S., the broiler industry will lose our ability to export which will have a significant impact on the industry – while costing billions and billions of dollars to the U.S. economy every year,” Super said.

With the way the disease is spreading, scientists would also probably have to vaccinate wildlife – which is nearly impossible.

Of the birds affected in this outbreak, about 76% are commercial egg-laying hens, 17% are turkeys, and only 5% are broilers, the chickens used for meat, Super said. The rest of the cases have been among ducks, backyard chickens and game birds.

“So the U.S. poultry sector that least needs a vaccine would have the most to risk from using one,” he said.

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FDA vaccine advisers vote to harmonize Covid-19 vaccines in the United States | CNN



CNN
 — 

A panel of independent experts that advises the US Food and Drug Administration on its vaccine decisions voted unanimously Thursday to update all Covid-19 vaccines so they contain the same ingredients as the two-strain shots that are now used as booster doses.

The vote means young children and others who haven’t been vaccinated may soon be eligible to receive two-strain vaccines that more closely match the circulating viruses as their primary series.

The FDA must sign off on the committee’s recommendation, which it is likely to do, before it goes into effect.

Currently, the US offers two types of Covid-19 vaccines. The first shots people get – also called the primary series – contain a single set of instructions that teach the immune system to fight off the original version of the virus, which emerged in 2019.

This index strain is no longer circulating. It was overrun months ago by an ever-evolving parade of new variants.

Last year, in consultation with its advisers, the FDA decided that it was time to update the vaccines. These two-strain, or bivalent, shots contain two sets of instructions; one set reminds the immune system about the original version of the coronavirus, and the second set teaches the immune system to recognize and fight off Omicron’s BA.4 and BA.5 subvariants, which emerged in the US last year.

People who have had their primary series – nearly 70% of all Americans – were advised to get the new two-strain booster late last year in an effort to upgrade their protection against the latest variants.

The advisory committee heard testimony and data suggesting that the complexity of having two types of Covid-19 vaccines and schedules for different age groups may be one of the reasons for low vaccine uptake in the US.

Currently, only about two-thirds of Americans have had the full primary series of shots. Only 15% of the population has gotten an updated bivalent booster.

Data presented to the committee shows that Covid-19 hospitalizations have been rising for children under the age of 2 over the past year, as Omicron and its many subvariants have circulated. Only 5% of this age group, which is eligible for Covid-19 vaccination at 6 months of age, has been fully vaccinated. Ninety percent of children under the age of 4 are still unvaccinated.

“The most concerning data point that I saw this whole day was that extremely low vaccination coverage in 6 months to 2 years of age and also 2 years to 4 years of age,” said Dr. Amanda Cohn, director of the US Centers for Disease Control and Prevention’s Division of Birth Defects and Infant Disorders. “We have to do much, much better.”

Cohn says that having a single vaccine against Covid-19 in the US for both primary and booster doses would go a long way toward making the process less complicated and would help get more children vaccinated.

Others feel that convenience is important but also stressed that data supported the switch.

“This isn’t only a convenience thing, to increase the number of people who are vaccinated, which I agree with my colleagues is extremely important for all the evidence that was related, but I also think moving towards the strains that are circulating is very important, so I would also say the science supports this move,” said Dr. Hayley Gans, a pediatric infectious disease specialist at Stanford University.

Many others on the committee were similarly satisfied after seeing new data on the vaccine effectiveness of the bivalent boosters, which are cutting the risk of getting sick, being hospitalized or dying from a Covid-19 infection.

“I’m totally convinced that the bivalent vaccine is beneficial as a primary series and as a booster series. Furthermore, the updated vaccine safety data are really encouraging so far,” said Dr. David Kim, director of the the US Department of Health and Human Services’ National Vaccine Program, in public discussion after the vote.

Thursday’s vote is part of a larger plan by the FDA to simplify and improve the way Covid-19 vaccines are given in the US.

The agency has proposed a plan to convene its vaccine advisers – called the Vaccines and Related Biological Products Advisory Committee, or VRBPAC – each year in May or June to assess whether the instructions in the Covid-19 vaccines should be changed to more closely match circulating strains of the virus.

The time frame was chosen to give manufacturers about three months to redesign their shots and get new doses to pharmacies in time for fall.

“The object, of course – before anyone says anything – is not to chase variants. None of us think that’s realistic,” said Jerry Weir, director of the Division of Viral Products in the FDA’s Office of Vaccines Research and Review.

“But I think our experience so far, with the bivalent vaccines that we have, does indicate that we can continue to make improvements to the vaccine, and that would be the goal of these meetings,” Weir said.

In discussions after the vote, committee members were supportive of this plan but pointed out many of the things we still don’t understand about Covid-19 and vaccination that are likely to complicate the task of updating the vaccines.

For example, we now seem to have Covid-19 surges in the summer as well as the winter, noted Dr. Michael Nelson, an allergist and immunologist at the University of Virginia. Are the surges related? And if so, is fall the best time to being a vaccination campaign?

The CDC’s Dr. Jefferson Jones said that with only three years of experience with the virus, it’s really too early to understand its seasonality.

Other important questions related to the durability of the mRNA vaccines and whether other platforms might offer longer protection.

“We can’t keep doing what we’re doing,” said Dr. Bruce Gellin, chief of global public health strategy at the Rockefeller Foundation. “It’s been articulated in every one of these meetings despite how good these vaccines are. We need better vaccines.”

The committee also encouraged both government and industry scientists to provide a fuller picture of how vaccination and infection affect immunity.

One of the main ways researchers measure the effectiveness of the vaccines is by looking at how much they increase front-line defenders called neutralizing antibodies.

Neutralizing antibodies are like firefighters that rush to the scene of an infection to contain it and put it out. They’re great in a crisis, but they tend to diminish in numbers over time if they’re not needed. Other components of the immune system like B-cells and T-cells hang on to the memory of a virus and stand ready to respond if the body encounters it again.

Scientists don’t understand much about how well Covid-19 vaccination boosts these responses and how long that protection lasts.

Another puzzle will be how to pick the strains that are in the vaccines.

The process of selecting strains for influenza vaccines is a global effort that relies on surveillance data from other countries. This works because influenza strains tend to become dominant and sweep around the world. But Covid-19 strains haven’t worked in quite the same way. Some that have driven large waves in other countries have barely made it into the US variant mix.

“Going forward, it is still challenging. Variants don’t sweep across the world quite as uniform, like they seem to with influenza,” the FDA’s Weir said. “But our primary responsibility is what’s best for the US market, and that’s where our focus will be.”

Eventually, the FDA hopes that Americans would be able to get an updated Covid-19 shot once a year, the same way they do for the flu. People who are unlikely to have an adequate response to a single dose of the vaccine – such as the elderly or those with a weakened immune system – may need more doses, as would people who are getting Covid-19 vaccines for the first time.

At Thursday’s meeting, the advisory committee also heard more about a safety signal flagged by a government surveillance system called the Vaccine Safety Datalink.

The CDC and the FDA reported January 13 that this system, which relies on health records from a network of large hospital systems in the US, had detected a potential safety issue with Pfizer’s bivalent boosters.

In this database, people 65 and older who got a Pfizer bivalent booster were slightly more likely to have a stroke caused by a blood clot within three weeks of their vaccination than people who had gotten a bivalent booster but were 22 to 42 days after their shot.

After a thorough review of other vaccine safety data in the US and in other countries that use Pfizer bivalent boosters, the agencies concluded that the stroke risk was probably a statistical fluke and said no changes to vaccination schedules were recommended.

At Thursday’s meeting, Dr. Nicola Klein, a senior research scientist with Kaiser Permanente of Northern California, explained how they found the signal.

The researchers compared people who’d gotten a vaccine within the past three weeks against people who were 22 to 42 days away from their shots because this helps eliminate bias in the data.

When they looked to see how many people had strokes around the time of their vaccination, they found an imbalance in the data.

Of 550,000 people over 65 who’d received a Pfizer bivalent booster, 130 had a stroke caused by a blood clot within three weeks of vaccination, compared with 92 people in the group farther out from their shots.

The researchers spotted the signal the week of November 27, and it continued for about seven weeks. The signal has diminished over time, falling from an almost two-fold risk in November to a 47% risk in early January, Klein said. In the past few days, it hasn’t been showing up at all.

Klein said they didn’t see the signal in any of the other age groups or with the group that got Moderna boosters. They also didn’t see a difference when they compared Pfizer-boosted seniors with those who were eligible for a bivalent booster but hadn’t gotten one.

Further analyses have suggested that the signal might be happening not because people who are within three weeks of a Pfizer booster are having more strokes, but because people who are within 22 to 42 days of their Pfizer boosters are actually having fewer strokes.

Overall, Klein said, they were seeing fewer strokes than expected in this population over that period of time, suggesting a statistical fluke.

Another interesting thing that popped out of this data, however, was a possible association between strokes and high-dose flu vaccination. Seniors who got both shots on the same day and were within three weeks of those shots had twice the rate of stroke compared with those who were 22 to 42 days away from their shots.

What’s more, Klein said, the researchers didn’t see the same association between stroke and time since vaccination in people who didn’t get their flu vaccine on the same day.

The total number of strokes in the population of people who got flu shots and Covid-19 boosters on the same day is small, however, which makes the association a shaky one.

“I don’t think that the evidence are sufficient to conclude that there’s an association there,” said Dr. Tom Shimabukuro, director of the CDC’s Immunization Safety Office.

Nonetheless, Richard Forshee, deputy director of the FDA’s Office of Biostatistics and Pharmacovigilance, said the FDA is planning to look at these safety questions further using data collected by Medicare.

The FDA confirmed that the agency is taking a closer look.

“The purpose of the study is 1) to evaluate the preliminary ischemic stroke signal reported by CDC using an independent data set and more robust epidemiological methods; and 2) to evaluate whether there is an elevated risk of ischemic stroke with the COVID-19 bivalent vaccine if it is given on the same day as a high-dose or adjuvanted seasonal influenza vaccine,” a spokesperson said in a statement.

The FDA did not give a time frame for when these studies might have results.

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Flu, Covid-19 and RSV are all trending down for the first time in months | CNN



CNN
 — 

A rough respiratory virus season in the US appears to be easing, as three major respiratory viruses that have battered the country for the past few months are finally all trending down at the same time.

A new dataset from the US Centers for Disease Control and Prevention shows that the number of emergency department visits for the three viruses combined – flu, Covid-19 and RSV – have dropped to the lowest they’ve been in three months. The decline is apparent across all age groups.

Measuring virus transmission levels can be challenging; health officials agree that Covid-19 cases are vastly undercounted, and surveillance systems used for flu and RSV capture a substantial, but incomplete picture.

But experts say that tracking emergency department visits can be a good indicator of how widespread – and severe – the respiratory virus season is.

“There’s the chief complaint. When you show up to the emergency room, you complain about something,” said Janet Hamilton, executive director at Council of State and Territorial Epidemiologists. “Being able to look at the proportion of individuals that seek care at an emergency department for these respiratory illness concerns is a really good measure of the respiratory disease season.”

In the week following Thanksgiving, emergency department visits for respiratory viruses topped 235,000 – matching rates from last January, according to the CDC data.

While the surge in emergency department visits early in the year was due almost entirely to Omicron, the most recent spike was much more varied. In the week ending December 3, about two-thirds of visits were for flu, about a quarter were for Covid-19 and about 10% were for RSV.

Grouping the impact of all respiratory viruses together in this way offers an important perspective.

“There’s a strong interest in thinking about respiratory diseases in a more holistic way,” Hamilton said. “Transmission is the same. And there are certain types of measures that are good protection against all respiratory diseases. So that could really help people understand that when we are in high circulation for respiratory diseases, there are steps that you can take – just in general.”

Now, Covid-19 again accounts for most emergency department visits but flu and RSV are still the reason behind about a third of visits – and they’re all trending down for the first time since the respiratory virus season started picking up in September.

More new data from the CDC shows that overall respiratory virus activity continues to decline across the country. Only four states, along with New York City and Washington, DC, had “high” levels of influenza-like illness. Nearly all states were in this category less than a month ago.

Whether that pattern will hold is still up in the air, as vaccination rates for flu and Covid-19 are lagging and respiratory viruses can be quite fickle. Also, while the level of respiratory virus activity is lower than it’s been, it’s still above baseline in most places and hospitals nationwide are still about 80% full.

RSV activity started to pick up in September, reaching a peak in mid-November when 5 out of every 100,000 people – and 13 times as many children younger than five – were hospitalized in a single week.

RSV particularly affects children, and sales for over-the-counter children’s pain- and fever-reducing medication were 65% higher in November than they were a year before, according to the Consumer Healthcare Products Association. While “the worst may be over,” demand is still elevated, CHPA spokesperson Logan Ramsey Tucker told CNN in an email – sales were up 30% year-over-year in December.

But this RSV season has been significantly more severe than recent years, according to CDC data. The weekly RSV hospitalization rate has dropped to about a fifth of what it was two months ago, but it is still higher than it’s been in previous seasons.

Flu activity ramped up earlier than typical, but seems to have already reached a peak. Flu hospitalizations – about 6,000 new admissions last week – have dropped to a quarter of what they were at their peak a month and a half ago, and CDC estimates for total illnesses, hospitalizations and deaths from flu so far this season have stayed within the bounds of what can be expected. It appears the US has avoided the post-holiday spike that some experts cautioned against, but the flu is notoriously unpredictable and it’s not uncommon to see a second bump later in season.

The Covid-19 spike has not been as pronounced as flu, but hospitalizations did surpass levels from the summer. However, the rise in hospitalizations that started in November has started to tick down in recent weeks and CDC data shows that the share of the population living in a county with a “high” Covid-19 community level has dropped from 22% to about 6% over the past two weeks.

Still, the XBB.1.5 variant – which has key mutations that experts believe may be helping it to be more infectious – continues to gain ground in the US, causing about half of all infections last week. Vaccination rates continue to lag, with just 15% of the eligible population getting their updated booster and nearly one in five people remain completely unvaccinated.

Ensemble forecasts published by the CDC are hazy, predicting a “stable or uncertain trend” in Covid-19 hospitalizations and deaths over the next month.

And three years after the first Covid-19 case was confirmed in the US, the virus has not settled into a predictable pattern, according to Dr. Maria Van Kerkhove, the World Health Organization’s technical lead for the Covid-19 response.

“We didn’t need to have this level of death and devastation, but we’re dealing with it, and we are doing our best to minimize the impact going forward,” Van Kerkhove told the Conversations on Healthcare podcast this week.

Van Kerkhove says she does believe 2023 could be the year in which Covid-19 would no longer be deemed a public health emergency in the US and across the world, but more work needs to be done in order to make that happen and transitioning to longer-term respiratory disease management of the outbreak will take more time.

“We’re just not utilizing [vaccines] most effectively around the world. I mean 30% of the world still has not received a single vaccine,” she said. “In every country in the world, including in the US, we’re missing key demographics.”

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Should you attend that New Year’s Eve party? Our medical analyst weighs in | CNN



CNN
 — 

At the end of 2020 and 2021, many people greeted the start of the coming year hunkered down due to the risk of Covid-19. But now, New Year’s Eve events and celebrations are back in a big way. A lot of people have plans to attend social functions, whether they are crowded festivities with thousands or house parties with a few relatives and friends.

These gatherings are occurring as the United States is in the midst of a triple threat — a confluence of respiratory syncytial virus or RSV, influenza and Covid-19. All three viral infections are spread from person to person, and gatherings involving many people can increase transmission at a time when hospital capacity nationwide is at near-record levels: More than 70% of inpatient beds are in use across the country, according to the US Department of Health and Human Services.

What should you consider in deciding whether to attend New Year’s Eve parties? How can you gauge the risk of specific events? Are there individuals who may want to take more precautions, and which mitigation measures can reduce risk if they go? If you find out later that an attendee was ill, when should you test afterward to make sure you are in the clear? And what happens if you develop symptoms after an event?

To guide you through these questions, I spoke with CNN Medical Analyst Dr. Leana Wen, an emergency physician, public health expert and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She is also the author of “Lifelines: A Doctor’s Journey in the Fight for Public Health.”

CNN: What should people consider in deciding whether to attend New Year’s Eve parties?

Dr. Leana Wen: People should start by considering three factors. First, what is your risk and the risk of your household from severe outcomes due to respiratory viruses? If everyone is generally healthy and you have already resumed other aspects of pre-pandemic activities, it might be reasonable to do the same for New Year’s get-togethers. But if someone is elderly or severely immunocompromised, you may wish to take additional precautions.

Second, what’s the importance of these events to you, compared with the importance of avoiding infection? Virtually every in-person interaction has some level of risk. That doesn’t mean everyone should avoid in-person activities permanently, but if you do attend a higher-risk event, know that you have a chance of getting a respiratory infection from it. Whether you go depends on how you weigh the importance of that event versus your desire to not get sick.

Third, is there a specific timing issue for which you really don’t want to get sick heading into the new year? For example, someone who has an operation scheduled the week after New Year’s may wish to be extra careful, so they don’t get an infection and then have to postpone their surgery. Someone else may have an important work event or school exam, and the desire to avoid any infection before that occasion could outweigh the desire to participate in New Year’s Eve celebrations. These are all things to consider and will vary depending on individual preference.

CNN: How can people gauge the risk of different New Year’s Eve events?

Wen: The risk depends on the type of event and what kind of mitigation measures are put into place, if any.

The more people, the higher the risk. A small gathering of, say, 10 close friends means that you could potentially contract respiratory viruses from one of these 10. Especially if these friends have been fairly cautious themselves, chances are low that none of these 10 are infected coming into the party. Compare that with a large party of 1,000 people. In this case, chances are much higher that someone at that party is infectious.

An outdoor event will be lower risk than an indoor event. Indoor events where everyone is spaced out, and where there is good ventilation, will be safer than ones where people are crowded close together.

In addition to space and ventilation, another mitigation measure that can make a difference is testing. If the event requires same-day rapid Covid-19 tests, that reduces risk. And it helps if the organizers emphasize that people who are symptomatic should not attend.

CNN: What are some things people can do to reduce their risk if they do go to an event?

Wen: Flu, RSV and a lot of other respiratory infections are spread through droplets. Washing your hands well and often can reduce your risk. Bring hand sanitizer with you in case it’s not readily available and use it frequently, especially after shaking hands and touching commonly used surfaces like shared serving utensils.

You could also stand near windows and try to stay away from crowds, especially if people are gathering in areas that aren’t well-ventilated.

Covid-19 is airborne in addition to being transmitted through droplets. Studies have shown that masks reduce the risk of Covid-19 transmission. Some venues may require masks, but even if they don’t, if you are someone who is very concerned about Covid-19, you could wear a high-quality N95 or equivalent mask during the event.

If you find out a partygoer at an event you attended had Covid-19, take a test five days after the gathering, Wen advised.

CNN: If you find out that someone at an event had Covid-19, when should you test afterward to make sure you are in the clear?

Wen: If you are asymptomatic, you should test at least five days after the event. If you test earlier than that, the test result might be negative, and you could still have contracted Covid-19, even if the virus in your body hasn’t replicated enough for the test to detect it yet. To be certain, I’d test five days after and then again two days after that.

CNN: What if you saw other people on New Year’s — if you were exposed on New Year’s Eve, could you infect people the day after?

Wen: The incubation period for Covid-19 is at least two days. Even if you did contract Covid-19 on New Year’s Eve, you wouldn’t have enough virus in your system to infect other people the day after. By the next day, two days after exposure, it’s possible.

CNN: What happens if you develop symptoms after an event?

Wen: If you develop symptoms, you should test for Covid-19, and then, if you test positive and you are eligible for Paxlovid, speak with your health care provider about taking the antiviral treatment. Inform the event organizer right away so that they can alert others.

Viral symptoms are not just due to Covid-19, of course. If you are someone who is particularly vulnerable, you should call your health care provider, who can test you for influenza and prescribe the antiviral Tamiflu. Children and other vulnerable people should get tested for RSV, too.

Otherwise, the advice is the same as pre-pandemic: Refrain from going to public places while symptomatic. Use standard measures to treat viral syndromes — such as fluids, rest, fever-reducing medicines and other symptom-based treatment.

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