How the COVID-19 vaccines work
February 04, 2021
You’ve gotten the COVID-19 vaccine. Now what?
BY Cynthia DeMarco
Last updated March 11, 2021
You’ve gotten a COVID-19 vaccine. That’s a big, welcome milestone. After months of masking, social distancing and seemingly endless hand-washing, you now have extra protection.
But what does being vaccinated really mean, in terms of how to live your daily life? Is it safe to socialize with your friends and extended family now? Do you still need to wear a mask and stay socially distanced from them, if you do? What if they’ve been vaccinated, too?
Before you start making plans, here’s what you should know.
You need both COVID-19 vaccine doses and time to ensure maximum protection
Johnson & Johnson's Janssen (J&J) COVID-19 vaccine requires only one dose; the Pfizer and Moderna vaccines require two. Both the Pfizer and Moderna vaccines confer some level of protection after the first dose. But if you get either of those two-dose vaccines, it’s important to get the second dose for maximum protection.
“If you’re only halfway through your two-dose vaccine regimen, you could be only about 50% protected until you receive the second required dose,” says Roy Chemaly, M.D., chief infection control officer.
The Pfizer vaccine is delivered in two separate doses that are given 3 weeks apart. The Moderna vaccine is delivered in two separate doses given 4 weeks apart.
Data from the Pfizer and Moderna clinical trials shows you need to get the second dose of these vaccines to achieve a higher level of protection. Vaccine recipients are up to 50% protected against the possibility of a severe infection about 10 days after the first dose, and up to 95% protected about seven days after the second one.
So, you shouldn’t leave any of your vaccination appointments assuming you’re fully protected immediately.
Vaccination doesn’t guarantee you won’t get a COVID-19 infection
Both the Pfizer and Moderna vaccines prevent up to 94% of recipients from developing a severe case of COVID-19, and the J&J vaccine prevents up to 67% of moderate to severe infections. But none of these vaccines protects you from developing any case at all. And preliminary data show they are also effective against the current mutations from South Africa and the United Kingdom, though that may not be true for future strains.
“All three COVID-19 vaccines are very effective, but they are not 100% effective,” says Chemaly. “A small percentage of those who receive the vaccine will not be protected from a COVID-19 infection.”
You may be still be able to spread the coronavirus after you’re vaccinated
We don’t yet know whether the vaccines protect against asymptomatic transmission of the coronavirus, Chemaly says.
“This would enable you to pass the virus to someone else even after you’ve been vaccinated, which is why it’s so important to continue wearing a mask, practicing social distancing and washing your hands regularly,” he notes.
Continue to avoid large gatherings and indoor get-togethers
Being vaccinated significantly reduces the odds you’ll develop a severe case of COVID-19. “But our national COVID-19 vaccine supply is still limited right now, so not everyone around you will be able to get vaccinated right away,” says Welela Tereffe, M.D., chief medical executive.
This means it’s still unsafe — even after vaccination — to gather in large groups or to have indoor gatherings that mix members from different households.
New guidance for fully vaccinated people
New guidance issued by the Centers for Disease Control and Prevention (CDC) does offer some flexibility for people of average risk who’ve been fully vaccinated.
If you’re not immunocompromised and it’s been two weeks since you’ve received either the second dose of the Pfizer or Moderna vaccine or the single dose of the J&J vaccine, the CDC says it’s OK to visit with other fully vaccinated people indoors, without wearing a mask.
You can also spend time unmasked indoors with a small group of unvaccinated people from another household, provided none of them are at increased risk.
“But the rules are different for cancer patients,” says Chemaly. “And any groups larger than that should only meet outside, even if everyone present is vaccinated. All non-essential business and leisure travel should still be postponed, too.”
Don’t let down your guard yet
So, how much longer will the pandemic last, and when can we finally take off our masks and hug all the people we love?
Chemaly says the answer to those questions is both easy to say and hard to predict: when we reach herd immunity. At least 70% of the population will need to be vaccinated or have natural immunity in order to achieve that milestone. And since the coronavirus is still so new, there’s simply not enough data available yet to say when that might occur.
“We really don’t know and I don’t want to guess exactly when that will be,” says Chemaly. “It depends on how quickly the vaccine is widely distributed, and how many people will take it. We just have to wait and see what the data show.”
Until then, the same rules apply after vaccination as did before vaccination: keep wearing a mask, social distancing and washing your hands. “We’re confident that vaccination will help us get through this,” Chemaly says, “but we can’t let down our guard yet.”
Request an appointment at MD Anderson online or by calling 1-877-632-6789.
TopicsCOVID-19 COVID-19 Vaccine
We can’t let our guard down yet.
Roy Chemaly, M.D.
Chief Infection Control Officer