Testing positive for coronavirus after getting a vaccine? Here’s how likely that is and what to know if it happens
Jan 5, 2021
It’s still possible to test positive for the coronavirus even after getting vaccinated, experts said.
Both the Pfizer-BioNTech and Moderna vaccines require two doses per patient to be fully effective. The first Pfizer-BioNTech dose is more than 50% effective in preventing COVID-19, and the second dose increases that protection to about 95%.
The Centers for Disease Control and Prevention said it can take weeks for a person’s body to build up immunity after getting vaccinated.
“That means it’s possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick,” the agency said. “This is because the vaccine has not had enough time to provide protection.”
Nicole Iovine, an infectious disease expert and hospital chief epidemiologist at University of Florida Health, said it takes the average person 10 to 14 days to build up a protective number of antibodies, but each person is different.
“Every day that goes by, the chance you get infected goes down a little bit,” she said. “Any individual person may make an immune response faster or slower than average.”
Dr. Richard Zimmerman, a professor of family medicine and public health at the University of Pittsburgh, said it takes a few weeks for a person to build up to the intended level of immunity after the second dose.