Why are some people getting COVID even after their first vaccine dose? What to know
Kendall Wilson received her first dose of the Moderna COVID-19 vaccine on Christmas Eve.
The next day, the 31-year-old office manager at a home health care service in Texas attended a holiday gathering of eight people, News12 reported. She tested positive for the coronavirus about a week later.
“I actually thought I’m good, I’m not going to get it. It’s not going to happen to me. And then, I was like, ‘I spoke too soon,’” Wilson told the outlet.
It’s the same story a handful of other health care workers share, and one that has been raising doubts in the vaccine across social media.
But Wilson’s case is not abnormal. Neither of the available vaccines offers 100% protection against the coronavirus, and the protection they do offer doesn’t appear immediately.
What’s more, both the Pfizer-BioNTech and Moderna vaccines require two doses, meaning people don’t have maximum immunity to COVID-19 following their first dose.
“It typically takes a few weeks for the body to build immunity (protection against the virus that causes COVID-19) after vaccination,” the Centers for Disease Control and Prevention says. “That means it’s possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and still get sick.”
Nicole Iovine, an infectious disease expert and hospital chief epidemiologist at University of Florida Health, told USA Today it can take the average person’s immune system 10 to 14 days to produce enough antibodies to provide a defense against the coronavirus.
“Every day that goes by, the chance you get infected goes down a little bit,” Iovine told the outlet. “Any individual person may make an immune response faster or slower than average.”
Wilson’s case of infection following a first dose is joined by another of a Southern California nurse who began feeling COVID-19 symptoms six days after receiving the first round of vaccination, testing positive two days later, according to ABC7.
“My guess is that they were exposed just before they got the vaccine and they weren’t showing symptoms yet or just afterwards,” Dr. Amy Herold, chief medical officer at Napa’s Queen of the Valley Medical Center, told the outlet.
Cases of people getting sick after their first dose are also appearing because the vaccines require two doses for maximum protection.
Dr. William Gruber, senior vice president of Pfizer Vaccine Clinical Research and Development, told the New York Times in December that its vaccine’s efficacy stands at about 52% following dose one, and about 95% after dose two.
The Moderna vaccine has an efficacy rate of 94% after both doses. This means there was a 94% reduction from the number of cases you would expect to see if clinical trial participants had not been vaccinated.
But U.S. Food and Drug Administration officials said data regarding the first dose of both vaccines is “commonly being misinterpreted,” according to a statement posted Monday.
“In the phase 3 trials, 98% of participants in the Pfizer-BioNTech trial and 92% of participants in the Moderna trial received two doses of the vaccine at either a three- or four-week interval, respectively,” FDA Commissioner Dr. Stephen Hahn and head of the FDA’s vaccine division Dr. Peter Marks, said in the statement.
“Those participants who did not receive two vaccine doses at either a three-or four-week interval were generally only followed for a short period of time,” so health officials do not know how long or how well a single dose protects recipients.
This week, health care workers across the nation started receiving their second doses of the COVID-19 vaccines.
More than 4.5 million Americans have been given their first dose of a coronavirus vaccine as of Jan. 4, according to a CDC tracker, but data on second doses have yet to be updated.
