Studies show that shots give significant immunity to survivors of COVID-19

Even people who have recovered from COVID-19 are encouraged to be vaccinated, especially as the number of highly contagious delta mutants surges. New studies show that survivors who ignore the advice are more than twice as likely to be re-infected.

A Friday report from the Centers for Disease Control and Prevention shows that people who have had a single COVID-19 attack dramatically increase the number of immune cells that fight the virus and gain broader protection bonuses against new mutants. Increasing room evidence. Vaccination.

“Even if you have been infected with COVID-19 before, get vaccinated,” said CDC Director Dr. Rochelle Walensky. “Vaccination is the best way to protect yourself and others around you, especially because more contagious delta variants are spreading throughout the country.”

One of the main reasons Americans are not planning to vaccinate, according to a new Gallup study, is the belief that they are already infected with COVID-19 and are protected. From the beginning, health authorities have urged survivors to obtain broader vaccination promises. Shots are not perfect, but they also provide strong protection against hospitalization and death from delta mutants.

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According to scientists, infections generally protect survivors from severe reinfections with at least similar versions of the virus, but blood tests show less protection against the mutants of concern.

CDC research provides some real-world evidence.

Researchers surveyed Kentucky residents with a coronavirus infection confirmed in the laboratory in 2020. The majority of them occurred between October and December. They compared 246 re-infected in May or June of this year with 492 similar survivors who remained healthy. Unvaccinated survivors had a significantly higher risk of reinfection than fully vaccinated survivors, but most had their first seizure of COVID-19 only 6-9 months ago. Woke up.

Another variant of the coronavirus caused most diseases in 2020, but the new alpha version prevailed in May and June in Kentucky, according to the lead author of the study, the U.S. Center for Disease Control and Prevention. Alyson Cavanaugh, who works with the Department of Health, said.

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It suggests that innate immunity from previous infections is not as strong as the boost that those people can get from vaccination while the virus is evolving.

Little information is yet available about reinfection with the new delta variant. However, U.S. health officials said Delta appears to be at greater risk of reinfection than the once-common alpha mutant, six months after the previous infection, according to early UK data. I’m pointing out.

Vaccination of survivors of COVID-19 “no doubt” improves both the amount and breadth of immunity. This “will allow us to cover not only the original (virus), but also the variants,” said Dr. Anthony Fauci, the U.S. government’s premier infectious disease expert, at a recent White House briefing. ..

The CDC recommends that everyone be fully vaccinated, that is, both vaccinated twice.

However, in another study published at the JAMA Network Open on Friday, researchers at Rush University found that a single dose of the vaccine dramatically increased the number of immune cells that fight the previously infected virus and infected them. He reported that he could get it with two injections than someone who had never done it.

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Other recent studies published in Science and Nature have shown that the combination of previous infections and vaccination also broadens people’s immunity to changing viruses. This is what virologist Shane Crotty of the Lahora Institute of Immunology in California calls “hybrid immunity.”

Vaccinated survivors “can make antibodies that can recognize all types of mutants, even if they have never been exposed to them,” Crotti said. “It’s pretty sweet.”

One of the warnings for those who are thinking of skipping vaccination if they have been previously infected: the amount of innate immunity varies from person to person and probably depends on the severity of the initial illness. A study from Rush University found that four of the 29 previously infected people did not have detectable antibodies before vaccination. The vaccine worked the same as a person who had never received COVID-19.

Why do so many previously infected people respond so strongly to vaccination? It has to do with how the immune system develops multiple protective layers.

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After either vaccination or infection, the body develops antibodies that can dodge the coronavirus the next time it tries to invade. They naturally declined over time. If the infection passes through them, T cells help prevent serious illness by killing the cells infected with the virus-and Memory B cells take action to make many new antibodies.

These memory B cells do more than just make a copy of the original antibody. John Wellie, an immunologist at the University of Pennsylvania, explained that in a bootcamp of the immune system called germinal center, antibody-producing genes are mutated to test the range of these virus fighters.

The result is essentially a library of antibody recipes that the body can choose after future exposure. The process becomes more powerful when vaccination triggers the original memory of the immune system’s fight against the actual virus.

Due to the hyperinfectivity of the delta mutant, vaccination despite previous infections is “more important now than before to be certain,” Crotti said. “The breadth of antibodies and their potency against mutants is much better than current antibodies.”

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The Associated Press’s Department of Health Sciences is supported by the Department of Science Education at the Howard Hughes Medical Institute. AP is solely responsible for all content.