Flu season in the Northern Hemisphere is nearly here, and experts are warning it could be a particularly bad one.
It’s also arriving at an inopportune moment. We’re starting to see early signs that another Covid-19 wave may already be starting: In Western Europe, infections, cases of severe disease and hospitalizations are on the rise.
Before flu season begins in earnest, I turned to my colleagues Carl Zimmer, a science reporter, and Melinda Wenner Moyer, who writes the Well Newsletter, for insight and advice.

How does flu season unfold?
Melinda: The exact timing of flu seasons varies, but it can start ramping up in October and usually dies down by mid-March. Peak flu activity spans from December through February.
But during the pandemic, the spread of flu has been much more variable.
In fact, last year we saw a lot of flu activity really late, like into April, May and June. We don’t really know why, but it could be because Covid restrictions started easing more around that time and people were traveling more.

What do we know about this flu season?
Melinda: We can look at what’s happened in the Southern Hemisphere — their flu season is usually finishing up when ours is getting started. And it has been a pretty bad flu season down there, which does not bode well for us.
Experts are also worried that because we’ve had such a mild flu season the last few years, there’s not a lot of immunity in the population, especially in very young kids, who may not ever have encountered the flu. So the worry is that without much immunity, it’s going to spread like wildfire, and it might even be a little more severe for people who haven’t encountered it recently.
Carl: People are also starting to relax Covid measures, and it looks like those measures worked very well against influenza. For a couple of years, influenza rates were very low in the United States, Australia and a lot of other countries. So low, in fact, that it’s possible that one type of the flu went extinct.

While a lot of work goes into understanding the flu, it’s still a lot of educated guesswork.
Part of that guesswork is the question of how well vaccines will work each year, because they have to pick a strain months in advance.

What do you mean?
Carl: The World Health Organization has a special group of scientists who keep track of flu cases around the world. They’re getting information about how different types of the flu are becoming more common or less common. And when it’s time for new vaccines to be made, they look at all the research that’s been done and make a recommendation for companies that produce them.

How good are the guesses?
Carl: Some years they’re pretty good and some years they’re not. Last year, we actually had a badly matched flu vaccine.

Even in a year where it’s a bad match, it’s still a good idea to get the vaccine. In a year that it’s a good match, the vaccine is going to do a good job of keeping you from getting infected, and if you do get infected it’s going to reduce your odds of going into the hospital. In years where it’s not a good match, you may not get that much protection against infection, but you’re still much less likely to end up in the hospital.

How else could we do it?
Carl: There are scientists who are working on universal flu vaccines, but they’ve been working on them for a long, long time. These vaccines would teach the immune system to recognize parts of the flu virus that don’t change year to year. A universal vaccine would give you protection for years, perhaps decades. I’m still hopeful that they will be working in our lifetime, but we’ll just have to wait and see.

What’s stopping us from making a universal flu vaccine?
Carl: The biology is very complicated, but there is one in clinical trials. Now the hope is that they work the way we want them to. Unfortunately, there’s no Operation Warp Speed for the flu. If there were, we might have a universal flu vaccine by now. But it’s been a pretty low priority.

Advice for flu season

What’s the best way to protect ourselves against the flu?
Melinda: Getting a flu vaccine. The vaccine also protects other people around you by possibly preventing you from getting it and spreading it — so you might even end up saving someone’s life. The things that work with Covid help with the flu as well, including wearing masks and social distancing.
Hand washing is also potentially more important for the flu than it is for Covid. The virus is known to transmit through touching surfaces, so during flu season we should make sure to wash our hands regularly and use hand sanitizer more frequently.

When should I get my shot?
Melinda: So that is a little tricky. The experts I talked to said you want to have the vaccine before you encounter the flu, but you don’t necessarily want it months before.
They suggest keeping track of the flu in your area. The C.D.C. has a website where you can see where flu activity is high. For example, Texas, Georgia and Washington, D.C., look pretty bad right now. So if you see that the flu is starting to spread where you live, then getting a flu shot as soon as possible is smart.
Some researchers I spoke to said that unless there’s high flu activity where they live, they will wait until mid-October or sometimes even early November to get their flu shots. Some were timing it to get a little more protection over the holidays. They also said that since they were delaying their shots, they were wearing masks more and social distancing more now to reduce their risk of infection.

What should I do if I get the flu?
Melinda: If you think you might have the flu, it’s important to stay home and rest so that you can get better and minimize the chance of infecting others.
Also, if you think you might have it, call your doctor and consider getting a flu test, because if you get diagnosed with the flu early enough, you might be eligible to get antivirals that can reduce the length and severity of the illness.

How should we think about the flu in terms of Covid?
Carl: Right now in the U.S., there are around 400 people dying a day from Covid, and death rates are much lower than during previous moments of the pandemic. That would still add up to more than double the deaths from the flu in a year. Covid also has a lot of impacts on the body that the flu doesn’t. It can lead to all sorts of issues in other organs in a way that we do not see so much with the flu.
That being said, we know that the flu can surge into a pandemic. We’ve seen it happen several times in the past 150 years. The worst was the 1918 flu pandemic, where over 50
million people died. These are both viruses that you don’t want to play around with.