Odds is, you’ve got COVID-19 — whether you know it or not. Nearly 60% of people in the US have antibodies in their blood showed they were infected with SARS-CoV-2, the virus that causes COVID-19, according to new estimates by the US Centers for Disease Control and Prevention.
But that doesn’t mean that 60% of people in the US are immune to COVID-19. “We know that’s not the point of this. Reinfection will happen,” said Dr. Kristie Clarke, co-leader of the CDC’s COVID-19 Epidemiology and Surveillance Task Force, during an April 26 press conference. and protection from previous infections wanes over time. ”
Even two years and millions of cases of infection turn into a pandemic, researchers are still learning about immunity to the virus and how long you can expect to stay disease-free after getting a shot or getting sick. . Here’s what the latest science says about immunity to COVID-19.
If I had COVID-19, can I get it back?
Your immune system has several different defenses against SARS-CoV-2. White blood cells called B cells produce antibody proteins, which help fight invaders. Meanwhile, T cells, another type of white blood cell, can destroy cells that have been taken over by the virus.
Research from UK researchers published in New England Journal of Medicine in March found that infection-related immunity remained strong for up to a year, then began to wane – while the protection provided by two doses of the Pfizer vaccine- BioNTech started to wane after about six months. While, a research review published in Annals of Internal Medicine in April, concluded that people who had recovered from COVID-19 had significant protection against reinfection for at least seven months.
But all that research was done before it appeared Omicron variant, more contagious than previous strains. Co-author Dr Mark Helfand, professor of medicine at Oregon Health & Science University, said: “We can’t really predict how the protection will work for the next variant. by or over a period of time.
Children can keep antibodies longer than adults, According to a new study from researchers at the Indiana University School of Medicine. They found that six months after infection, more children than adults still had antibodies capable of neutralizing the virus.
While those findings should offer some comfort to people who have had COVID-19, there are no guarantees of immunity. (A woman in Spain recently caused a stir when she tested positive for COVID-19 twice, only 20 days apart.) Some people develop more antibodies after an infection than others. It’s also unclear exactly how antibody levels correlate with protection against infection, so a positive antibody test doesn’t necessarily mean you’re immune to the virus, Clarke said at the meeting. CDC report.
Dr Bruce Farber, head of infectious diseases at Northwell Health in New York, said there’s no way to say for sure how long a person recovering from COVID-19 can stop worrying about being reinfected. . However, he allowed, it would be “very unusual” to receive COVID-19 within 90 days of the previous case.
If I am fully vaccinated, am I immune to COVID-19?
The COVID-19 vaccine also prompts the body to produce antibodies and trigger a T-cell response, although these are different from the response the body produces naturally.
Vaccines provide strong, long-term protection against severe illness and death, but their effectiveness against infection diminishes over time, so your risk is lowest. immediately after your most recent dose. A research review published year fingertips in March, analyzed data from previous studies that evaluated the effectiveness of different COVID-19 vaccines, including those made by Moderna, Pfizer-BioNTech, AstraZeneca and Johnson & Johnson. Across all brands, the vaccines’ ability to prevent symptomatic disease fell by 20% to 30% after six months, the researchers found, although they were still good at preventing serious illness and death. This review was also published before the Omicron variant—against which vaccine is less effective?—Beginning to spread widely.
However, even with Omicron circulating, a vaccinated person was 2.4 times less likely to test positive for the virus in March than an unvaccinated person, According to CDC.
Jessica Ridgway, associate professor of medicine at the University of Chicago and co-author of the program, said: a recent study on reinfection with COVID-19. “They are extremely safe and having an extra level of immunity would certainly be helpful to prevent COVID,” she said. Furthermore, research shows that getting a booster dose can help provide protection to even higher levels.
What happens if I get vaccinated? and have COVID-19?
If you recovering from COVID-19 and receiving a COVID-19 vaccineyou have what is called “hybrid immunity”. Studies show this type of protection is better than vaccination or exposure alone, because you benefit from both natural and vaccine-derived defenses.
“The best immunity, without a doubt, is hybrid immunity,” says Farber.
Of course, you should never try to catch COVID-19 for the sake of achieving hybrid immunity. While it is very unusual for a vaccinated and generally healthy person to have a severe case of COVID-19, complications can occur. People got Long COVID even though they were fully vaccinated and experience some symptoms, for example.
Do I need to keep receiving COVID-19 boosters forever?
US Food and Drug Administration (FDA) recently authorized a second batch of boosters for people 50 years of age and older, as well as certain immunocompromised people in all age groups. Additional boosters are yet to be licensed for the entire population — but there is a lot of speculation about whether they will ever be used, as vaccine-related immunity will wane over time. time.
The FDA’s Vaccine Advisory Committee met in April to discuss ways to Streamlined and improved reinforcement strategy move forward. An annual dose, like the flu shot, is a possibility – but the SARS-CoV-2 virus mutates in more unpredictable ways than the flu virus, so it’s difficult to pre-generate a targeted booster. to any subsequently circulating strains.
A better model might be to develop boosters that provide immunity to multiple variants. That science is underway nowbut it is too early to say exactly what the future promotion strategies will look like.
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