The staff at Tufts Medical Center in Boston are on alert for a possible “twin-demic” of COVID-19 and the flu this winter.”If you add them on top of each other, it will stress hospitals to near their breaking point or beyond,” said Dr. Shira Doron, the hospital epidemiologist at Tufts Medical Center.The impact of both viruses to the human body could be just as catastrophic.Each virus on its own has the potential to damage lungs and blood vessels, and cause inflammation of the heart, brain or muscle tissues.”You do not want another virus on top of COVID. So for all those reasons, the flu shot is again extremely important this year,” Doron said.Everyone at least 6 months old is eligible to get a flu shot. Ideally, people should schedule a shot before the end of October.Like the COVID-19 vaccine, it takes about two weeks to generate enough antibodies to offer protection, so waiting past Halloween or until flu season starts could be too late.”If you get the flu and you’ve got that chronic cough, that’s a reflection of some underlying lung damage,” Doron said. “That means your reserves are low and if you were to get COVID, you could have a more severe case.”Last winter, health officials were anxious they would see more patients in the U.S. with both viruses, but that did not happen.Masks, physical distancing and the closed classrooms that slowed down the spread of COVID-19 nearly stopped the flu.”So things are different now. We’re not wearing masks as much. We’re not distancing as much. Things are open,” Doron said.Therefore, the risk of double infection is back and local doctors are holding their breath.”When you suppress viral transmission for some period of time, it’s possible for it to come back with a vengeance,” Doron said.The flu virus itself mutates faster than the coronavirus, but the shot is designed each year to protect against the strains most likely to circulate.Even if the match isn’t exact, the shot may still prevent many flu symptoms.”The vaccine isn’t going to be reconfigured once the flu arrives, so the vaccine is the vaccine for the season,” Doron said.People can receive a COVID-19 vaccine or booster and the flu shot on the same day, even in the same arm, as long as the injection sites are at least an inch apart. The vaccines will not interact or interfere with each other.But in order to minimize the risk of a potential reaction, the U.S. Centers for Disease Control and Prevention advises getting the flu shot in the dominant arm and the COVID-19 vaccine in the other.