As the coronavirus continues to spread across the country, there are frequent reports of fully vaccinated people contracting COVID-19. Experts say these "breakthrough cases" are expected, and want to assure people the vaccines are still highly effective.
Clinical trial data showed that the Pfizer-BioNTech, Moderna and Johnson & Johnson coronavirus vaccines were extremely effective in preventing disease, but Dr. Bill Moss, a pediatrician and professor of infectious disease epidemiology at the Johns Hopkins Bloomberg School of Public Health in Baltimore, noted that some people in the trials did contract the virus.
"95% efficacy is not 100% efficacy," said Andrew Heinrich, a lecturer at the Yale School Of Public Health in New Haven, Connecticut.
"There are going to be some people who are not protected, even by two doses of the vaccine, but they should have more mild disease," said Moss. "... The vaccines are really highly protective against severe disease, so even those who get COVID-19 after two doses of vaccine are much more likely to have mild disease."
Still some people who are fully vaccinated can become very sick and die. An NBC News survey of health officials nationwide found that those who experience more serious disease despite being fully vaccinated tend to be older than 65, have a compromised immune system or other health conditions.
How can I avoid getting COVID-19 after being vaccinated?
The same rules continue to apply for mitigating risk of contracting the coronavirus: wash your hands frequently, wear a mask when in crowded settings or around unvaccinated people and social distance.
While the Centers for Disease Control and Prevention say that fully vaccinated individuals do not need to wear masks (unless on airplanes, buses, trains and other modes of public transit), some areas may issue local mask mandates. Last week, Los Angeles County reinstated their indoor mask mandate as the more contagious delta variant is now the dominant strain of the virus in the U.S.
Heinrich said that an important thing people can do is urge their loved ones to get vaccinated.
"Vaccines matter most when a significant portion of the population gets them," Heinrich said. "It's a bit of a logarithmic scale and (as more people get vaccinated), the benefits start to mount immensely. The best thing you can do to make your vaccine as effective as possible for yourself and your family is to get everyone around you vaccinated ..."
Can I spread COVID-19 after being vaccinated?
According to Heinrich, the "jury is still out" on whether you can carry and spread COVID-19 after being vaccinated, but some studies on the topic appear to offer optimism.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said during a White House coronavirus response team briefing that early studies are "pointing in a very favorable direction." However, further studies will be necessary on the topic.
This story was updated on July 19, 2021 to include updated guidance.
CORRECTION (March 26, 10:30 AM): An earlier version of this article misstated Andrew Heinrich’s title as a professor at the Yale School of Public Health. He is a lecturer at the Yale School of Public Health, not a professor.