Shannon Romano, a molecular biologist, came down with COVID late last March, about a week after she and her colleagues shut down their lab at Mount Sinai Hospital. A debilitating headache came first, followed by a fever that kept rising, and then excruciating body aches. "I couldn't sleep. I couldn't move," she said. "Every one of my joints just hurt inside."
It was not an experience she wanted to repeat — ever. So when she became eligible for the COVID-19 vaccine recently, she got the shot.
Two days after her injection, she developed symptoms that felt very familiar. She recovered quickly, but her body's intense response to the jab caught her by surprise.
A new study may explain why Romano and many others who have had COVID report these unexpectedly intense reactions to the first shot of a vaccine. In a study posted online Monday, researchers found that people who had previously been infected with the virus reported fatigue, headache, chills, fever, and muscle and joint pain after the first shot more frequently than those who had never been infected. COVID survivors also had far higher antibody levels after both the first and second doses of the vaccine.
Based on these results, the researchers say, people who have had COVID-19 may need only one shot.
"I think one vaccination should be sufficient," said Florian Krammer, a virus expert at the Icahn School of Medicine at Mount Sinai and an author of the study. "This would also spare individuals from unnecessary pain when getting the second dose and it would free up additional vaccine doses."
While some scientists agree with his logic, others are more cautious. E. John Wherry, director of the University of Pennsylvania's Institute for Immunology, said that before pushing for a change in policy, he would like to see data showing that those antibodies were able to stop the virus from replicating. "Just because an antibody binds to a part of the virus does not mean it's going to protect you from being infected," he said.
It might also be difficult to identify which people have previously been infected, he said.
Side effects after vaccination are expected. They show that the immune system is mounting a response and will be better prepared to fight off an infection if the body comes into contact with the virus. The Pfizer and Moderna vaccines are particularly good at evoking a strong response. Most participants in the companies' trials reported pain at the injection site, and more than half reported fatigue and headaches.
It is not necessarily surprising that previously infected individuals might experience more intense reactions. Both shots contain bits of genetic material that spur the body to manufacture spike proteins. People who have already been infected with the virus have immune cells that are primed to recognize these proteins. So when the proteins show up after vaccination, some of those immune cells go on the attack, causing people to feel sick.
People who have had COVID seem to be "reacting to the first dose as if it was a second dose," said Akiko Iwasaki, an immunologist at the Yale School of Medicine.
A study published recently reported that surviving a natural infection provided 83% protection from getting infected again over the course of five months. "Giving two doses on top of that appears to be maybe overkill," she added.