Tanya Lewis: Hi, and welcome to Covid Quickly, a Scientific American podcast series! This is your fast-track update on the COVID pandemic. We bring you up to speed on the science behind the most urgent questions about the virus and the disease. We demystify the research, and help you understand what it really means.

I’m Tanya Lewis, one of Scientific American’s senior health editors. Josh is taking the week off. Today, I’m going to talk about the “triple-demic” of COVID, flu and RSV. And I’ll also talk about why it’s so important to get the new COVID booster shot to make sure you’re fully protected.

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Lewis: If it seems like everyone around you is getting sick lately, it’s because they are. But this time, it’s not just COVID making the rounds—it’s also flu and a virus called RSV.

COVID cases have been pretty flat lately at around 38,000 cases a day, although these are likely a vast undercount because many people are testing at home. But as we discussed last episode, the new Omicron subvariants could drive a winter surge.

The variants all have mutations that make them better at getting around our immunity from vaccination or prior infection. But experts think the vaccines should still provide good protection against severe disease and death. Now’s a good time to get your booster if you haven’t already—more on that later.

As for flu, it all but disappeared the last couple of years during the pandemic, because people were staying home, wearing masks and social distancing. That’s no longer the case. The southern hemisphere had a pretty bad flu season during their winter (our summer), which usually bodes poorly for the northern hemisphere.

Flu cases in the U.S. have already started spiking—especially in the South and New York City. And hospitals are reporting more positive tests. This is earlier than a typical flu season, which usually peaks between December and February. It’s important to get your flu shot now if you haven’t yet—you can get it at the same time as your COVID booster, or space it out by a few days if you normally get a strong reaction to either shot.

But let’s talk about RSV, or respiratory syncytial virus. If you’ve never heard of it before, you’re not alone. But you’ve almost certainly had it. Before COVID, most children got RSV before the age of two. It usually causes mild symptoms similar to the common cold.

But in infants under six months old, it can sometimes be dangerous. That’s because it causes inflammation in the small airways of the lungs, known as bronchiolitis. And in very young children, their airways are so small that this inflammation can make it hard to breathe.

More recently, we’ve started to learn that adults over 65 are also at risk of severe RSV. Doctors don’t typically test for it, but about 14,000 adults die from RSV every year—not that many fewer than die from flu every year. People whose immune systems are compromised are especially at risk.

Like many respiratory viruses, RSV basically disappeared during the pandemic’s first year, but it came roaring back in summer of 2021. That’s because many children had not been exposed to it as infants but were suddenly mingling and getting sick. The same thing is happening now, and hospitals are filling up with RSV.

There are no approved treatments for RSV, so it’s usually treated with supportive care. As far as vaccines, scientists have been working on those since the 1960s, but faced setbacks after a vaccine trial that resulted in the deaths of two children who got RSV after getting the vaccine. But there are now several promising vaccine candidates. 

Pfizer just reported that its maternal RSV vaccine, which is given during pregnancy, was more than 80 percent effective at preventing severe RSV in infants under three months. And both Pfizer and GSK have both announced positive results for a vaccine for adults 60 and older. At least one of these vaccines will likely be approved by the end of next year, according to Barney Graham, a former NIH scientist who has spent his career working on an RSV vaccine.

The best way to protect yourself against RSV is the same as for COVID and flu: stay home when you’re sick if you’re able to, wear a good mask, stay in well-ventilated spaces. In the case of RSV specifically, you should also wash your hands, because you can also get it from touching surfaces.

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Lewis: Circling back to COVID, let’s not forget that we’re still in a pandemic. And making sure you’re up to date with your COVID booster is the best thing you can do to protect yourself from getting severely ill. At this point in the pandemic, many of the people dying of COVID are actually older people who are vaccinated, but not up to date on their boosters. (That doesn’t mean the vaccines don’t work—it’s just that so many older Americans are vaccinated that a small percentage is still a big number.)

I talked to the FDA’s chief medical officer, Hilary Marston, about why the new bivalent booster shots are so important. Unlike the original boosters, the new one targets both the original strain of the virus and the Omicron BA.4 and BA.5 subvariants, which are related to those currently circulating. “Obviously, the importance of booster shots just couldn’t be greater than at this moment, as the weather is getting colder and we’re all inside more,” Marston told me.

Everyone five and older is eligible for a booster shot. Experts recommend waiting at least two months since your last booster or three months since a COVID infection in order to get the best immune response.

But booster uptake has been truly abysmal. Fewer than 10 percent of eligible Americans have gotten the new shot. And this is frustrating, because we have the tools to prevent people from getting severely ill. Marston points out that health care workers will bear the brunt of it: “They’re going to be there to take care of you if you do get sick, of course, but it is just such a strain,” she said.

Early data on the new booster shot’s efficacy is still coming out, but it looks promising—including against the new variants. The shot may not stop you from getting COVID, but it just might save your life.

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Lewis: Now you’re up to speed. Thanks for joining us. Our show is produced by Jeff Delviscio and Tulika Bose. Come back in two weeks for the next episode of COVID, Quickly! And check out sciam.com for updated and in-depth COVID news.