- This story is regularly updated for relevance. Last updated: May 6, 2021
So, you got your first dose of the COVID vaccine. That’s great. You must be relieved to finally let your guard down. Except, quite literally, do not do that. At least not yet. That’s because you can still get COVID even after you’ve received the vaccine.
While the rollout of coronavirus vaccinations plays an integral part in getting life back to normal sooner rather than later, it’s only a means to an end. And simply getting the first dose of the COVID vaccine still leaves you susceptible to the disease caused by the novel coronavirus.
According to a recent study published in The New England Journal of Medicine, protection from the Pfizer-BioNTech vaccine doesn’t start until 12 days after the first dose. It won’t reach 52% effectiveness until a few weeks later, and protection doesn’t attain the full 95% until a week following the second immunization.
Moderna reported a similar effectiveness rate in its application for authorization—51% two weeks after the first dose and 94% two weeks after the second. The main discrepancy between the two results is that Moderna measured the efficacy of its vaccine starting 14 days after the second dose, while Pfizer began measuring after seven days.
Regardless of which vaccine you receive, the Centers for Disease Control and Prevention states that building immunity “typically takes a few weeks.”
In other words, even those who are vaccinated can still be exposed before the body has a chance to develop defenses against the virus. “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 gets sick,” the CDC warned.
To help people better understand what the vaccine does and does not do, Dr. Stella Clavecilla, a California-based board-certified internal medicine specialist, put together this handy TikTok video that quickly breaks down the science.
How safe are you after the second dose of the COVID vaccine?
Though both Pfizer and Moderna’s vaccines provide approximately 95% protection in clinical trials, that’s still less than 100%—which means that some people may still become infected even after receiving both doses. It will take some time before the overall efficacy rate goes down, and we begin to achieve herd immunity.
“That’s not 100%,” Paul Offit, director of the Vaccine Education Center and a member of the Food and Drug Administration’s vaccine advisory board, told NPR. “That means one out of every 20 people who get this vaccine could still get moderate to severe infection.”
Another troubling part of the puzzle that experts still don’t understand is whether the vaccines protect against all infections or just symptomatic infections. According to the CDC, an estimated 40% of coronavirus infections are asymptomatic. And both Pfizer and Moderna only examined if their respective vaccines prevented symptomatic infections.
But in mid-March, a Pfizer study showed its vaccine was 97% effective against symptomatic COVID and 94% effective against asymptomatic COVID. A few weeks later, Pfizer said its version was fully effective against the variant that was found in South Africa.
In February, it was also reported that early trials in South Africa showed the AstraZeneca vaccine did not protect against the COVID-19 variant that originated in that country (in March, Austria and Denmark suspended use of AstraZeneca due to blood-clotting issues). But the one-dose Johnson & Johnson vaccine, which was approved in the U.S. at the end of February, seemingly performed better in South Africa than the original data showed.
So, not only does getting both doses of the vaccine not give you full protection against the virus, but even so-called “healthy” individuals may still possibly transmit to others—vaccinated or unvaccinated. That means that it will continue to be essential to mask up, wash your hands, and practice social distancing for the foreseeable future, even as restrictions inevitably begin to relax and millions of more people get vaccinated.
Some people are well aware that they can’t yet let down their guard. And some, even after they’re vaccinated, are still terrified that they’ll catch the virus.
Still, the effectiveness of the vaccines is impressive. “I’ve been a vaccinologist for four decades, and I’ve never seen efficacy like this in first-generation vaccination,” Dr. Gregory Poland, an infectious disease physician at the Mayo Clinic, told AARP.
Read more on the coronavirus vaccines:
- What happens to all the unused COVID vaccines?
- Can the COVID vaccine give you herpes?
- All U.S. adults now eligible for COVID-19 vaccine, but some are still holding out
- Will you need a COVID-19 booster shot? And an annual vaccine?
- Should you get more than 1 COVID vaccine?
- If you got the COVID vaccine but didn’t experience any side effects, is it still working?
- Which COVID vaccine is the best?
- How long will the COVID-19 vaccines keep you safe from the coronavirus?
- Can you drink alcohol after getting the coronavirus vaccine?