What is COVID-19 vaccine breakthrough?
Vaccine breakthrough occurs when someone gets sick with a disease they are fully vaccinated against. For the COVID-19 vaccine, this means someone tests positive for COVID-19 two weeks or more after receiving the full series of an authorized COVID-19 vaccine. The series is either one or two doses, depending on which vaccine you got.
Some people could get COVID-19 soon after vaccination when their body hasn't had enough time yet to build full protection. These infections are not called vaccine breakthrough cases because you're not yet considered fully vaccinated during that time. It typically takes about two weeks after the final dose of vaccine for the body to build protection against the disease.
How are vaccine breakthrough cases identified?
The criteria for identifying vaccine breakthrough cases include a positive lab test (either a PCR test or an antigen test) more than 14 days after a person received the last recommended dose of an authorized COVID-19 vaccine.
How often does this happen?
COVID-19 vaccine breakthrough is uncommon because all COVID-19 vaccines currently being used in the United States are highly effective. However, since none of the vaccines are 100% effective, we expect to see some vaccine breakthrough. Millions of people in the United States are getting vaccinated, and a small proportion of those vaccinated people will still become infected with COVID-19. Breakthrough cases do not mean that something is wrong with the vaccine. As of April 2021, vaccine breakthrough has occurred in about 0.01 percent of Washington's fully vaccinated population.
Does the vaccine really work if I got COVID-19 anyway?
Yes! Vaccines for COVID-19 continue to be an essential tool to protect people against COVID-19 illness because the COVID-19 vaccines are very effective.
Large-scale clinical studies found that COVID-19 vaccines prevented most people from getting COVID-19 illness, but they are not 100% effective. However, even though some vaccinated people may still get sick, data from the clinical studies also showed that COVID-19 vaccines were very effective against hospitalization and death from COVID-19. That means if you do get sick after you're fully vaccinated, you still have some benefit from the vaccine because you may only get a mild case instead of a serious case.