WASHINGTON — Question:
Can a fully vaccinated person become infected with COVID-19?
Yes. Medical experts explained to the Verify team that the vaccines are highly effective at stopping COVID-19, but they are not perfect. Some people will still get infected, even though they are vaccinated.
Medical experts emphasize that those who are unlucky enough to get infected after being fully vaccinated are not likely to have severe symptoms, as the vaccines were 100% effective at preventing hospitalizations and death in trials.
- Dr. Diane Griffin, Professor of Molecular Microbiology and Immunology at Johns Hopkins Bloomberg School of Public Health
- Dr. William Moss, Executive Director of the International Vaccine Access Center at Johns Hopkins Bloomberg School of Public Health
- Dr. Bruce Walker, Director of the Ragon Institute of MGH, MIT, and Harvard
- Efficacy Studies For Pfizer, Moderna, and Johnson and Johnson
The Verify team is a resource for people at home, who are questioning what they're seeing online. Recently the team received an email from a viewer named Connie. She said she had received both of her vaccines in January, and then tested positive for COVID-19 in March.
"My concern is how did I get COVID-19 after being vaccinated?" she asked.
To track down the answer, the Verify team spoke with a trio of medical experts, including Dr. William Moss from Johns Hopkins University.
"These vaccines are not 100% protective," Dr. Moss said. "I think that's the bottom line. They're 95% protective."
Dr. Moss was referring to the efficacy data released for the three approved vaccines in the United States. Pfizer had an efficacy rate of 95% and Moderna had an efficacy rate of 94% in trials. Johnson and Johnson had a lower, but still impressive, efficacy rate of 72% in the U.S.
Since these vaccines are not 100% effective, it's inevitable that some people will still get infected.
"Some just didn't get enough of a response to be protected," Dr. Diane Griffin from Johns Hopkins University said.
What does efficacy rate mean?
There has been a lot of confusion circulating online about what these efficacy rates mean. Some have wondered whether a 95% efficacy indicates that five percent of those who received the vaccine would still get sick.
This is false.
Efficacy rates indicate how much better the vaccine group did in trials compared to the placebo group.
For example, one can look at the Pfizer study, which showed an efficacy rate of 95%. It evenly split those studied between a vaccine group and a placebo group. Among those given a placebo, 162 people had a confirmed case of COVID-19, compared with just 8 people among the vaccine group, who tested positive for COVID-19.
Here's why the vaccine matters, even for those who get sick
Essentially, our viewer got unlucky. She was part of a small minority that doesn't get as much protection from the vaccine. However, this is not to suggest that she didn't benefit from the vaccine at all.
All three of the vaccine trials demonstrated a 100% effectiveness in keeping people from being hospitalized or dying. Our viewer may have had a much greater reaction to the disease if she was not vaccinated.
"The vaccines prevent severe disease," Dr. Bruce Walker from the Ragon Institute in Massachusetts said. "Even with the variants. That's been proven with the Johnson and Johnson vaccine."
Dr. Griffin said that this often happens with the flu vaccine, which is far less effective in stopping infection overall, compared to these COVID-19 vaccines. Even when getting the flu, symptoms tend to be less severe, if one has been vaccinated.
"Even if you get infected, you get a milder disease than you might have if you had never been vaccinated," Griffin said.