Experts aren’t sure what this season’s flu will look like.this is the reason

Flu season has officially started. If COVID and the flubipolar disorder“(probably”triple demic“with respiratory virus RSV), or occasional double infection”fluorine,” experts say no one knows exactly what lies ahead.

Massachusetts health officials weekly flu reportSo far the severity has been declared as ‘low’. Clinic visits for ‘flu-like illness’ are higher than at this point in the past three seasons, but remain lower than typical for non-flu seasons.

Nationally, most states are reporting increased influenza activity, with the highest levels in southern states.

Despite the uncertainty about what lies ahead, here’s why flu epidemics are so difficult to predict, and why some researchers are optimistic about new flu vaccines. Let’s take a look at our best guesses for this season’s flu.

What health experts can expect this flu season

Experts worry we’re going to have a worse flu season than usual. There are two main reasons for this concern.

First, the past few flu seasons have been particularly mild. Without immunity from recent infections, “more people may be susceptible to influenza this year than in previous years,” said Larry, medical director of the Massachusetts Department of Public Health’s Office of Infectious Diseases and Laboratory Sciences. Mr Madoff explains.

Weakened immunity and less mask wearing could make flu season worse.

Second, experts often look to the southern hemisphere, which has just finished its flu season, as an indicator of what will happen in the northern hemisphere.of Australia Especially things didn’t go well.

“They had a very bad flu season, a severe flu season that was about three times the normal flu level,” Madoff said. There is reason to believe that there is [here]”

Brian Chow, an infectious disease doctor at Tufts Medical Center, is also looking at the Australian data. But he found reasons for cautious optimism. “They hit hard early on, with cases dropping significantly, which is encouraging for the northern hemisphere,” he said.

One thing experts agree on is that no one knows what flu season will be like until it happens.

“We can’t predict it very well. Every flu season is different, especially now. [with COVID]said Madoff. “All I can say is that we’re seeing a lot of unusual patterns in respiratory illness these days.”

Why flu is hard to predict

There are several reasons why the severity of flu season is difficult to predict.

Influenza viruses are constantly evolving. As such, it’s difficult to know which strains will be trending each year. Some strains are slightly more contagious. Others are slightly less so. “These small changes can make a big difference in a large population,” Chow said.

Dr. Jennifer Wang, professor of infectious diseases at UMass Chan Medical School, said researchers are thinking about how the virus is changing in terms of “drift” and “shift.”

“Drift” is when there are small, subtle changes in the viral genome.she is this Mismatch between vaccine and circulating virus. This means that many unvaccinated people do not do well to fight if they are not vaccinated.

A “shift” is a change in a large portion of the viral genome. “That’s mixing with animals,” Wang said, citing two well-known examples of swine flu and bird flu. Very few people did. “Then our immune systems are very unprepared,” Wang said.

Another unpredictable factor in flu season is the weather. Changes in temperature and humidity affect how long the virus can survive outside the body.

“We also know that cold, dry weather promotes flu transmission and pushes people into indoor, crowded places,” Madoff said.

“Global warming makes it even more difficult to predict,” Chow added. This is because weather patterns in both hemispheres are changing and becoming more difficult to predict.

Finally, how influenza interacts with COVID is a big new unknown.

Every flu season is different, but the last two flu seasons have been particularly unusual. There was little influenza activity in 2020-21. From 2021 to 2022, there was an early and late spike, but a significant decrease in cases when influenza usually peaks.

Experts believe some of this is due to pandemic precautions. Good hand hygiene, wearing masks, and many staying home and avoiding crowds. But Wang thinks it’s likely something else is going on.

She said there are far fewer co-infections, in which people have the flu and COVID at the same time, than experts had expected.

“I remember thinking at the beginning of the pandemic, ‘We’re going to see a lot of double infections.’ We didn’t see that. In fact, COVID took over. It happened again last winter.” When Omicron took off, infectious disease experts like Wang noticed a sharp drop in flu infections.

It is possible to be infected with both viruses at the same time, but research suggests that you may be infected with more viruses. serious illness — seems unusual. Wang speculates, “Maybe it had something to do with how our bodies reacted to her COVID infection, which could provide a hostile environment for the flu.” there is.”

Other experts say it’s too early to tell how the viruses will interact, which makes it even harder to predict what the flu season will look like. .

Hope for the future?

Wang is part of a team working to create a new flu vaccine using mRNA, the building block of some COVID vaccines.

“This could really change how we treat flu in the future,” she said.

The standard flu vaccine involves injecting inactivated influenza virus into the body to provoke an immune response. Flu mRNA vaccines basically contain a cellular blueprint that stimulates the body to make flu proteins (or parts thereof) and kick-start the immune system.

In most years, the standard flu vaccine is about 40% effective in preventing infection, Wang said, and the best case is 60% effective.she leads Massachusetts site Testing a new mRNA flu vaccine — this one is produced by Pfizer — against standard flu vaccines.

She hopes that the mRNA flu vaccine will be more effective. Also, she said, mRNA vaccines are better suited for situations where circulating flu strains and vaccines don’t match because they can be updated quickly.

“These mRNA vaccines can be modified very quickly in the lab,” she said. I can do it.”

Wang expects the results of a nationwide flu vaccine clinical trial to be available before next year’s flu season. As for this year, experts recommend getting a standard flu vaccine by the end of October.