A new study, published early on medRxiv on Feb. 21 and not yet peer-reviewed, found that people who have been previously infected with COVID have more intense side effects after receiving the first dose of the COVID vaccine, compared to those who have not been infected. These coronavirus survivors were more likely to experience systemic side effects such as fatigue, headache, chills, fever, and muscle or joint pain. The researchers say that these adverse reactions after the first dose are similar to the more intense reactions people who haven’t been infected with COVID are reporting after their second dose. And for more on vaccine reactions, Dr. Fauci Says He Had These Side Effects From His Second Vaccine Dose. According to the study, the antibody response created by the vaccine in those that have been infected by COVID is 10 to 20 times higher than those who were vaccinated but never had COVID. Not only that, but the researchers also said that the antibody response in COVID survivors after just the first dose exceeded the median antibody amount measured after the second dose in those who never had the virus—which likely explains COVID survivors’ higher levels of notable side effects following the first shot. Some experts say this may mean those who have already been infected with the coronavirus only need one dose of the vaccine. “I think one vaccination should be sufficient,” Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai and an author of the study, told The New York Times. “This would also spare individuals from unnecessary pain when getting the second dose, and it would free up additional vaccine doses.” And for more coronavirus news, If You Have This Common Habit, Your COVID Symptoms Will Be Worse. Not every expert is ready to change vaccination guidelines, however. E. John Wherry, director of the University of Pennsylvania’s Institute for Immunology, told The New York Times that he would like to see data showing that the antibodies produced in COVID survivors after the first dose were actually effective in stopping the virus from replicating before recommending they only get one shot. “Just because an antibody binds to a part of the virus does not mean it’s going to protect you from being infected,” he explained. Wherry also said that it may be too troublesome to identify who has already had the virus. “Documenting that becomes a really potentially messy public health issue,” he added. And for more up-to-date information, sign up for our daily newsletter. As of right now, the policy is that COVID survivors should still get two vaccine doses like anyone else. According to the CDC, “due to the severe health risks associated with COVID-19 and the fact that reinfection with COVID-19 is possible, you should be vaccinated regardless of whether you already had COVID-19 infection.” The only exception the agency notes is that those who have been recently infected with COVID may delay their vaccination while vaccine supplies are limited, since the risk of COVID reinfection is low in the months after initial infection. And for more essential vaccine guidance, If You’re Over 65, You Shouldn’t Get This New Vaccine, Experts Warnae0fcc31ae342fd3a1346ebb1f342fcb