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Even people who have recovered from COVID-19 urged to get vaccinated, especially as the extra-contagious delta variant increases – and new study shows survivors who ignored this advice were more than twice as many likely to be re-infected.
Friday’s report from the Centers for Disease Control and Prevention adds to growing laboratory evidence that people who have had a COVID-19 attack get a dramatic boost in anti-virus immune cells – and a more protection bonus wide against new mutants – when vaccinated.
“If you’ve had COVID-19 before, please still get the vaccine,” CDC director Dr. Rochelle Walensky said. “Getting the vaccine is the best way to protect yourself and others, especially as the most contagious delta variant is spreading across the country.”
One of the main reasons Americans give for not intending to get vaccinated is the belief that they are protected because they already have COVID-19, according to a new Gallup survey. From the start, health officials urged survivors to secure broader protective immunization promises. While the shots aren’t perfect, they offer strong protection against hospitalization and death, even from the delta mutant.
Scientists say the infection generally leaves survivors protected from serious re-infection with at least a similar version of the virus, but blood tests have reported that protection wanes against the disturbing variants.
The CDC study offers concrete evidence.
Researchers studied Kentucky residents with lab-confirmed coronavirus infection in 2020, the vast majority of them between October and December. They compared 246 people who were re-infected in May or June this year with 492 similar survivors who remained healthy. Survivors who were never vaccinated had a significantly higher risk of reinfection than those who were fully vaccinated, although most had their first episode of COVID-19 as little as six to nine months ago.
A different variant of the coronavirus caused most illness in 2020, while the new alpha version was predominant in Kentucky in May and June, said lead study author Alyson Cavanaugh, a CDC disease sleuth working with that state’s health department.
This suggests that the natural immunity against a previous infection is not as strong as the boost these people can get from the vaccination as the virus progresses, she said.
There is still little information about re-infections with the new delta variant. But U.S. health officials point to early data from Britain that the risk of reinfection appears greater with delta than with the once common alpha variant, once people are six months after their previous infection.
“There is no doubt” that vaccinating a COVID-19 survivor improves both the amount and extent of immunity “so that you cover not only the original (virus) but the variants”, Dr Anthony Fauci, the US government’s top infectious disease expert, said at a recent White House briefing.
The CDC recommends a full vaccination – that is, two doses of the two-dose vaccines – for everyone.
But in a separate study published Friday in the JAMA Network Open, researchers at Rush University reported that a single dose of the vaccine gives previously infected people a dramatic boost in anti-virus immune cells, more so than people. who have never been infected receive two injections.
Other recent studies published in Science and Nature show that the combination of a previous infection and vaccination also expands the strength of people’s immunity against a changing virus. This is what virologist Shane Crotty of the La Jolla Institute for Immunology in California calls “hybrid immunity”.
Vaccinated survivors “can make antibodies that can recognize all kinds of variants even if you’ve never been exposed to the variant,” Crotty said. “It’s pretty sweet.”
A warning for anyone considering skipping the vaccination if they have had an infection in the past: the degree of natural immunity may vary from person to person, possibly depending on the state of the disease in the past. departure. The Rush University study found that four of the 29 previously infected people did not have detectable antibodies before they were vaccinated – and the vaccines worked for them just like they work for people who never have. had COVID-19.
Why do most people previously infected have such a robust response to vaccination? It has to do with how the immune system develops multiple layers of protection.
After vaccination or infection, the body develops antibodies that can repel the coronavirus the next time it tries to invade it. These naturally decrease over time. If an infection gets past them, T cells help prevent serious illness by killing cells infected with the virus – and memory B cells kick in to make many new antibodies.
These memory B cells don’t just make copies of the original antibodies. In immune system boot camps called germinal centers, they also mutate antibody-producing genes to test a range of these virus fighters, explained University of Pennsylvania immunologist John Wherry.
The result is essentially a library of antibody recipes for the body to choose from after future exposures – and this process is stronger when the vaccination triggers the immune system’s original memory to fight the actual virus.
With the super infectivity of the delta variant, getting vaccinated despite a previous infection “is more important now than before to be sure,” Crotty said. “The extent of your antibodies and your potency against the variants will be much better than what you have now.”
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The Associated Press’s Department of Health and Science receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
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