Is the U.S. Heading Toward a ‘Twindemic’? What You Need to Know This Flu Season

flu season


Health officials fear the country could be a collision course with Covid-19 and the flu. 

This October marks the beginning of flu season — and this year is particularly worrisome with the ongoing coronavirus pandemic. 

Health officials across the U.S. have already started using the term “twindemic” to refer to the possibility of the health care system being overwhelmed by an increase in Covid-19 and flu cases. Lynnette Brammer, an official at the Centers for Disease Control, tells us flu cases are still “incredibly low,” but they’re starting to pick up and only expected to increase over the coming months. 

“I definitely believe we’ll see more flu this year than we did last year and anything we can do to reduce the impact of flu circulation this year will be really helpful because the healthcare system’s been really stressed,” says Brammer, who leads the CDC’s Domestic Influenza Surveillance team, which is responsible for collecting, analyzing, and publishing a weekly report on flu activity. 

Amid concerns about these two infections overlapping, we turned to Brammer as well as epidemiologists Richard Zimmerman and Michael Mina to weigh in. 

Why are health officials especially concerned about this flu season?

Health experts say Americans have built up less natural immunity against influenza and other viruses because of “record low” cases in 2020 amid widespread lockdowns. This means that viruses could have more potential to spread this fall as some cities start to reopen more. In fact, the return of common viruses, like respiratory syncytial virus (RSV), has already put many toddlers in the hospital with severe cases this year. 

While continued mitigation efforts like mask-wearing and social distancing could help flu cases at bay, Brammer said it likely won’t be enough to have another record low flu year due to widespread school reopenings and the return of travel. Just last week, the Biden announced that the U.S. would be reopening its borders to fully vaccinated foreign visitors Nov. 8. 

“Things are opening up a little bit here and there for travel and people are starting to behave more as they did before the pandemic,” she says. 

What are the symptoms of Covid-19 and the flu?

The initial symptoms of both Covid-19 and the flu are both very similar. Brammer says typical flu symptoms include fevers, coughs, sore throat, body aches, but these symptoms could be also indicators of Covid-19 or other similar viruses like RSV. Still, it’s worth noting that RSV and cold are generally milder, with a runny or stuffy nose more likely. 

How can you tell the difference between Covid and the flu?

Trying to tell the difference between various respiratory illnesses is not easy, even for doctors. “I don’t think on the basis of symptoms, you can tell the difference between flu, between flu RSV [respiratory syncytial virus], and Covid,” says Dr. Zimmerman, who is a professor at the University of Pittsburgh. “It’s hard for me to differentiate as a doctor who’s been doing this for decades.” But he tells us that the tell-tale symptom of Covid is the loss of taste or smell. 

Another key factor to pay attention to is how quickly your symptoms develop. Do they start slowly over the course of a few days or do you suddenly wake up feeling horrible? Dr. Mina, who is an assistant professor at Harvard, points out that while Covid-19 symptoms have more of a slow progression, flu symptoms can be sudden and aggressive. What also makes the flu distinct is that symptoms can often improve before getting a lot worse. In this case, Dr. Mina warns that this could be a sign of a bacterial infection, which he says could be much worse than the influenza virus itself. 

But, ultimately, if you’re unsure about your symptoms, all three experts recommend getting tested for Covid, visiting a doctor, or both. 

How effective is the flu shot? 

Making the annual flu shot has always been a challenge because it’s hard to know which strains will circulate and the virus is notorious for mutating quickly. Brammer says it was also especially tricky last year because scientists had a lot fewer cases to study, but she expressed confidence in the vaccine’s effectiveness. “We got a really good sample of what there was and that those viruses are what the one circulating this season will come from, so I don’t think our ability to select the vaccine strains was compromised,” she said. 

The flu vaccine also remains key in preventing serious cases of the flu. But that doesn’t mean it’s going to prevent all infections because no vaccine is 100 percent effective. Similar to the Covid-19 vaccine, there could be some breakthrough infections with the flu shot but the experts agree that it’s effective in preventing both deaths and hospitalizations.

“Even if you do get flu this year, despite being vaccinated, as long as your influenza infection is not particularly severe, you should assume that the vaccine actually helped it,” says Dr. Mina.

When should you get your flu shot?

The CDC is urging people to get it by the end of October. But Brammer notes that it’s never too late to get your flu shot as flu season often stretches several months, with peak cases typically between December and February. 

But getting your flu shot is also crucial ahead of the holiday season amid family gatherings. “My family and I — from my mom to my adult children — are vaccinated against both Covid and flu each year, so we would encourage people to receive their flu vaccine, particularly before Thanksgiving, because we don’t know when the flu will hit,” Dr. Zimmerman tells us.

And finally, is it safe to get a flu and Covid booster shot at the same time?

The timing of Covid-19 boosters and flu shots has become a common question now that flu season is here. The experts say it’s perfectly safe and effective to get both vaccines at the exact same time.

“The human immune system is capable of multiplexing, if you will, or kind of power processing — it can deal with many, many different vaccines at once because it’s designed to deal with many, many pathogens at once,” says Dr. Mina.  

Brammer recommends getting the shots in different arms if possible but if not, she advises getting them at least an inch apart to lessen any possible soreness.