As the holiday season ramps up, New York City and the rest of the nation are in the throes of a three-headed hydra of infectious disease.

Flu season has spiked early across the U.S., and COVID-19 is taking off post-Thanksgiving. Through the end of last week, the city was averaging about 1,100 daily emergency department visits due to flu-like illness, double the number from late October. Following the turkey gatherings, the city’s weekly tally of COVID-19 cases increased to more than 26,000 — compared against 19,000 the week prior. Both are likely undercounts, given the popularity of home testing. But likewise, hospitalizations are up 20%, while deaths are hovering around 120 per week.

Respiratory syncytial virus (RSV) infections remain high but are beginning to cool off after plaguing the area since October. The city health department recorded about 3,000 RSV cases the first week of December, down about 40% from early November. Like the flu, the annual arrival of RSV peaked months early.

New York City Health Commissioner Dr. Ashwin Vasan issued an advisory last week urging New Yorkers to take extra precautions as they gather and travel over the coming weeks. He joined “All Things Considered” host Sean Carlson on Monday to break down the best advice for facing the “tripledemic,” especially if New Yorkers get infected by the trio back to back.

The interview was lightly edited for clarity.

Sean Carlson: Why are so many people getting sick right now?

Vasan: We're not entirely sure why, but some of the hypotheses are that we've spent the last two viral seasons mostly masked, with more social distancing, and not moving about the same way. So our immune systems are a little bit unexposed to viruses relative to years past.

We're certainly seen that in younger kids who haven't had that normal exposure to viruses and disease that they have in schools. So that's probably the best hypothesis, but I don't know that anyone's nailed an explanation.

Your office is recommending that everybody masks up with high-quality masks.
What kinds are you recommending and what instances should they be putting them on in the first place?

Our first message is the best mask you can wear is the one you can get. We don't want trying to seek out a higher quality mask to be a barrier from wearing what’s most easily available to you.

That said, we know that higher-grade masks, like KN95s, KF94s and N95s, do provide significantly more protection against the transmission of all respiratory viruses. That's why we wear them in health care settings, where doctors, nurses and health care providers are exposed more frequently. And that's why we recommend it during this really unusual viral season that we're facing.

Do we know if masking protects us against RSV and the flu any better or worse than it does for COVID?

We know that masks unequivocally protect us against respiratory illness, airborne respiratory illness, which is why we issued the mask advisory last Friday.

It is really to say to New Yorkers, the holiday seasons haunt us. We want every New Yorker and every person to have the opportunity to celebrate in healthy ways with their family, community and congregation — something that's been stolen from us for the last two years.

The safest way to do that is to wear a mask when you're in public crowded settings, like subways, schools, elevators or crowded stores. You're doing your holiday shopping? It makes sense to wear a mask when you're going in and out of stores.

Can you walk us through the symptoms of RSV? How would you know that it's RSV and not the flu or COVID?

I think it's a great question — and really, really hard to tell to be perfectly honest.

These are respiratory viruses. They mostly affect the upper and lower respiratory tract. Every person who gets sick can be affected in slightly different ways.

Some might be more predisposed to a cough — or what we would call lower respiratory symptoms. Some folks might be more predisposed to upper respiratory symptoms like nasal congestion and sore throat.

It's a little bit hard to parse out, and that's why we recommend people get tested frequently, especially for COVID, which is easy to access.

But if you test negative for COVID and you are still feeling sick, it makes sense to go get tested for flu because we have a treatment: Tamiflu. If you take it within the first 48 or 72 hours, it can actually reduce your risk, reduce the duration of symptoms and keep you out of that severe flu episode, which you're at risk for especially if you're older or have an underlying chronic health condition.

We're all pretty familiar at this point with the idea of COVID-19 testing. Obviously, the flu's been around for quite some time, and people get tested for that.
Should they also be getting tested for RSV?

You can certainly get tested for RSV. There is no vaccine for RSV, though there is one in development, and there really isn't any specific treatment for RSV.

Let's be clear, most children before the age of two will get RSV, and most of them will recover at home. What we're worried about is particularly very small babies who have very small airways, and RSV can attack them in very severe ways.

And though we're seeing cases drop, we had seen a bit of a surge in pediatric emergency room visits. As well, we're seeing increased RSV cases in the elderly — people over 65 and especially people over 75 — who are getting atypical symptoms like severe cough and shortness of breath. That’s due to the fact that their immune systems are just not really exposed to RSV and that their immune systems are not as strong as younger, healthier people.

This is a common virus. It's been around a long time. If you feel yourself feeling sick, it's always a good idea to talk to your primary care provider. If you don't have a primary care provider, you can call 212-COVID-19 (212-268-4319). We can connect you to a primary care provider or even get you seen through telehealth – to get you Paxlovid or whatever treatment you might need, such as Tamiflu, or a referral to a primary care provider.

Some New Yorkers will probably remember — and not want to remember — those darkest days of the COVID pandemic when we didn't really know too much about how it was spread and we were disinfecting everything.
When it comes to RSV or the flu, should we be disinfecting surfaces? Should we be paying more attention to airplane seats or strollers for that matter?

You're absolutely right. We were all in a time of real uncertainty in terms of transmission in those early months, and so it's not surprising that we just tried to do everything.

What we recommend is really common sense hygiene, like hand hygiene. We've talked a lot about what good hand washing looks like. That's one of the key messages for this holiday season.

Wash your hands early and often; with soap; 20 seconds; sing Happy Birthday. Do that in addition to getting your COVID booster, in addition to getting your flu shot, in addition to getting tested frequently for COVID and getting treated if you're positive.

Wearing that mask and hand hygiene remained two simple, really easy ways for us to stay safe and prevent getting sick in the first place.

We're hearing that some people are getting COVID and then they're getting the flu and then they're getting RSV.
Do you have any thoughts on the best ways to recover from a series of infections like that?

The tincture of time is always the best recovery, and I really feel for people who are getting hit multiple times. It's a lot on the body.

If you have to go back outside for work or for any other reason, wear a mask even when you're recovering from the previous illness episode.

But the best way to recover if you are in that unfortunate category of getting hit multiple times is to first get diagnosed. It's important to know if you have COVID, if you have flu, or if you have RSV.

If you have the first two, there are treatments for those things, and they can shorten your illness course. And they can also shorten the severity of symptoms.

If you have RSV, the only thing to do is really rest, and there are a lot of supportive treatments – over-the-counter treatments, Tylenol, cough suppressants. Those are healthy, effective things to do. Staying home and resting is a really important piece.

Now, we have the updated COVID-19 boosters (the bivalent booster shots) in addition to the flu shot. Is it possible to get both of those in one go?

Absolutely, I did the same. I got both my COVID bivalent booster and my flu shot in September. They work in very different ways, so the side effects are mild, and there's no interaction between the two.

That's why we've been setting up pop-up vaccination sites all across this city to give out both the bivalent vaccine and the flu shot. New Yorkers can go to vaccinefinder.nyc.gov to schedule appointments for either or both. We encourage everyone to do that as soon as possible.