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After a quiet 2020 flu season, many medical experts are expecting an increase in cases this year. With the COVID-19 pandemic still rampant, could we be in danger of a so-called “twindemic?”   Flu season typically runs from October through April, and we asked Dr. John Greene, chair of the Infectious Diseases Program at Moffitt Cancer Center, for his thoughts on how both viruses may affect each other this season.

Q: What are your predictions for the upcoming flu season?

A: We really didn’t have a flu season last year, and so now that things are a little bit more opened up than usual, I think we’re going to see a few more flu cases this year, but nothing near a true epidemic proportion. There’s still a lot of public places like schools and colleges promoting masks, so you’re still going to have more than usual mask wearing, which reduces transmission of all viruses.

Q: How do doctors decide which flu shot to roll out?

A: Historically they look at the flu cases in the U.S. from the past year and then look at what’s happening in the Southern Hemisphere when they have their flu season to try to predict what’s coming towards us. Since we didn’t have a flu season, they don’t really know what’s going to emerge so they’re going to probably have to rely on the season before COVID-19 hit. I’m not sure there’s enough flu in the world right now to really predict what’s going to come next. 

Q: Is it safe to get a COVID-19 vaccine and a flu shot?

A: Yes, it’s safe to get them both, even at the same time. They stimulate your immune system in different directions. The difference is the mRNA COVID-19 vaccines stimulate your immune system to make antibodies to the spike protein to block attachment of the COVID-19 virus to the cells lining your airways. The flu vaccine stimulates your immune system to make antibodies to hemagglutinin or neuraminidase to various flu strains such as H1N1.

Q: Should I be concerned about side effects from both shots?

A: There’s likely going to be a brisk immune response. You could feel like you got the flu, or your arm could be sore because your immune system is going to be revved to the max. Usually those symptoms are gone within a few days to a week, so whether you want to get both at the same time, or space them out, that’s up to each person.

Q: How do you tell the difference between COVID-19 and flu symptoms?

A: The one thing that separates the two is that COVID-19 comes with the loss of taste and smell. The fevers, muscle aches, cough, runny nose, congestion or headaches can all happen with both. Gastrointestinal symptoms like nausea, vomiting and diarrhea can occur in both, as well.

Q: Do the same prevention techniques like mask wearing, hand washing and social distancing apply to both?

A: Looking at what we’ve learned from the COVID-19 epidemic, it’s the same for all airborne viruses. You do reduce transmission by doing these things. We know that there’s less transmission outdoors than inside poorly ventilated rooms. We know there’s less transmission when masks are worn. Hand washing doesn’t help as much when it comes to airborne viruses, but it’s still important to preventing the spread of diarrheal and foodborne illnesses.