The development of vaccines against COVID-19 has played a big role in helping reduce the number of new COVID-19 cases. But the time is approaching when a first dose isn’t enough anymore.
Booster shots are common with many vaccines and can help your immune system develop added protection against a virus. COVID-19 vaccine boosters are recommended for just about everyone roughly 5 months after the first series of vaccinations is complete.
According to the Centers for Disease Control and Prevention (CDC), almost 82 percent of people ages 5 and up in the United States have received at least one dose of a COVID-19 vaccine, and nearly 66 percent of the total U.S. population is fully vaccinated. But only about half of eligible people have received a booster dose.
There’s been evidence that infection with the coronavirus is still possible even after a booster dose of the COVID-19 vaccine. But experts say vaccination and boosters are still the best way to prevent serious illness or death from the coronavirus.
This article will review whether you can test positive for COVID-19 even after a booster shot and what this means for you.
Yes, you can test positive for COVID-19 even if you’ve been fully vaccinated and received a booster dose.
COVID-19 vaccines aren’t designed to prevent infection entirely, or even infection that you can transmit to others. The vaccines are designed to keep the amount of coronavirus in your body low enough to prevent severe illness.
Like with other vaccines, the antibodies your immune system creates after COVID-19 vaccination can decrease over time. This, combined with the emergence of new coronavirus variants, can lower the protection a vaccine offers you.
No vaccine is 100 percent effective, and several other illnesses require boosters or re-vaccination, like influenza. These boosters or updated vaccines may include additional information to help your immune system fight new variants, or prompt your body to create more, newer antibodies.
How well any vaccine can protect you depends on a few factors, such as:
your overall healththe state of your immune systemhow long it’s been since you were vaccinatedwhat new virus variants are circulating
It’s difficult to estimate how likely you are to develop a breakthrough coronavirus infection after a booster shot because variants are always creating new challenges.
Vaccines and boosters were very effective in preventing breakthrough infections in early coronavirus variants. Initially, your chances of having a breakthrough infection after a booster were about 1 in 5,000. By late 2021, when the Delta variant was widely circulating, those odds increased to about 1 in 100.
It may be too early to say how well the vaccines prevent Omicron variant infections in people who have received boosters. Still, early data indicates that the Omicron variant may be even better at evading the protection vaccines offered with previous versions of the virus.
A coronavirus infection is considered a breakthrough infection if you test positive 14 days after your booster dose.
But you may not even realize you’ve contracted an infection if you’ve been fully vaccinated and boosted. According to the American Medical Association (AMA), about a quarter of people who get a breakthrough infection after a booster don’t ever develop any symptoms of infection.
About 50 to 60 percent will develop COVID symptoms, reports the AMA, but these are usually mild. Only about 10 percent of people who develop a breakthrough infection will need to be hospitalized.
Whether you contract an infection without vaccination or with all your doses and boosters, the rules for quarantine are still the same. You may not be as sick if you get COVID-19 after a booster, but you’re still capable of transmitting the virus to others.
As of March 2022, the CDC recommends the following quarantine times for infection or exposure:
5-day quarantine for people who test positive but have no symptoms5-day quarantine followed by 5 days of mask wearing in public for people who test positive and have symptoms5-day quarantine followed by 5 days of mask wearing in public for people who are exposed to the virus and are unvaccinated or 6 months out from their last vaccine dose
People who are vaccinated and boosted are more likely to get a breakthrough infection from the Omicron variant than earlier variants like Delta. But early research suggests that a booster dose can reduce breakthrough infections by about 50 percent.
Can a booster shot cause me to test positive for COVID-19?
Booster shots contain the same ingredients as COVID-19 vaccines, and these vaccines do not contain any live virus. Even though you will develop spike protein antibodies, it’s not possible to test positive for COVID-19 from a PCR or antigen test as a result of initial or booster vaccination.
Can I get COVID-19 from a vaccine or booster?
No. COVID-19 vaccines are developed to give your immune system information on how to best detect and fight the virus that causes COVID-19.
Unlike some other types of vaccines, the COVID-19 vaccines do not contain actual virus, so they cannot cause an infection.
Should I still get a booster if I’ve already had COVID-19?
Yes. The natural immunity you develop after having COVID-19 provides a good deal of protection against reinfection. But this protection isn’t always as strong or long lasting as that from vaccines.
Breakthrough cases can happen with just about any type of vaccine, including those against COVID-19.
Research shows that full vaccination and boosters against COVID-19 can help reduce your likelihood of contracting the virus. People who are fully vaccinated and contract an infection are unlikely to become seriously ill. You may not even develop symptoms with a breakthrough infection.
The CDC offers additional resources to help you understand how vaccines work and why breakthrough cases can happen.