What experts expect this flu season

In the Southern Hemisphere, influenza cases picked up a bit earlier than they typically do in some countries, but ultimately didn't result in an especially large number of hospitalizations or deaths, experts said.

Experts also said this year's flu vaccine is a good match to the predominant strain of influenza.

One study found the current flu vaccine reduced the risk for flu-related hospitalizations by 52% in the Southern Hemisphere, which is a strong indicator of how effective the vaccine is, according to Alicia Budd, head of CDC's domestic influenza surveillance team.

Rick Zimmerman, a professor of family medicine and flu epidemiology at the University of Pittsburgh, cautioned that while epidemiologists tend to look at the Southern Hemisphere to predict this year's flu season, the United States doesn't always follow the same patterns.

"Sometimes you get a new variant that arises that they did not experience in the Southern Hemisphere," he said. And other times, the main influenza strain circulating in the Southern Hemisphere varies, making it difficult to predict what the U.S. flu season will look like.

Seema Lakdawala, an associate professor of microbiology and immunology at Emory School of Medicine, said flu cases will likely start rising soon now that COVID-19 cases are starting to drop.

Peaks of different types of viruses don't often overlap, Lakdawala said. Once you recover from one respiratory virus, it's unlikely you'll be infected with another one for around a month or two, as your innate immune response increases your protection from another infection.

When to get vaccinated and what to do if you're sick

CDC recommends that everyone ages six months and older get vaccinated for the flu. Ideally, those eligible for the flu vaccine got their shot by the end of October. However, it's still good to get vaccinated as long as influenza is circulating, which can stretch into the spring.

Once you get your shot, it'll take your body around a week or two to develop enough antibodies to protect you, Zimmerman said. Your antibody levels will peak around three to four weeks after you receive the vaccine and then will start to decline, but experts say you're still protected for around four to six months.

Shortly after you're vaccinated, your antibody levels are high enough that you could be protected from a nose infection as well as a chest or lung infection. Months later, when those antibody levels begin to decline, you won't be as protected above the throat but should still be protected in your chest.

"So you likely have protection for your lungs, which will keep you out of the hospital and keep you from getting really sick," Zimmerman said. "The vaccine may not prevent nose colds but it prevents a lot of hospitalizations and deaths due to heart and lung issues."

If you do get sick, especially if you're more at-risk for serious complications, you should see a doctor to determine whether you have the flu or COVID-19. Doing so early can help you get started on antiviral medication, which can help reduce the length and severity of your illness.

"The sooner you take it, the more effective it will be," Budd said. (Reddy, Wall Street Journal, 10/30)

AstraZeneca has submitted an application to  FDA that would allow its intranasal flu vaccine to be administered at home by individuals or caregivers instead of healthcare professionals, potentially increasing access to the vaccine.