It is very rare for someone to become infected with the coronavirus that causes COVID-19 disease a second time, but the few confirmed cases of reinfection tell us that immunity to the virus is not guaranteed and that vaccination could become a usual part of our doctor. care in the future.
There are approximately 50 confirmed cases of reinfection worldwide. This is well under 1% of the 110 million cases of coronavirus reported worldwide. BNO News, a Dutch news site, tracks infections worldwide; 51 confirmed cases of reinfection have been identified along with approximately 11,000 suspected or probable reinfections.
Reinfection is thought to occur when protective antibodies decrease in people who previously contracted the virus or in people who contracted the virus without developing antibodies.
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“I don’t think anyone had the expectation that if you have COVID and surpass it, you will never be able to get it again.”
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For some doctors with infectious diseases, this is no surprise.
“I think everyone predicted that there would be reinfections at some distant point after the initial infection,” said Dr. Bruce Polsky, an infectious disease doctor at NYU’s Langone Hospital in Long Island. “I don’t think anyone had the hope that if you have COVID and you pass it, you will never be able to get it again.”
The Centers for Disease Control and Prevention defines reinfection as a positive test for COVID-19 that occurs at least 90 days after the initial positive test. (This is to differentiate yourself from people with persistent “long COVID” symptoms). The public health agency says reinfection is rare; however, he also says he expects the number of reinfections to increase as the pandemic continues.
“The likelihood of SARS-CoV-2 reinfection is expected to increase over time after recovery from the initial infection due to decreased immunity and possibly genetic drift,” the CDC told the October.
As the pandemic reaches its second year, this could put at risk some of the approximately 27 million people in the U.S. who have already had COVID-19.
The duration of the pandemic, together with the appearance of the new, more infectious variants B.1.1.7 and B.1.351, may also pose a risk for a second SARS-CoV-2 virus infection. The CDC has said that strain B.1.1.7, confirmed in 1,523 Americans as of Feb. 16, could become the most dominant form of the virus in the United States by the end of March. Variant B.1.351, first identified in South Africa, has been detected in 21 people in the US
“Yes [B.1.351] becomes dominant, the experience of our colleagues in South Africa indicates that even if you have been infected with the original virus, there is a very high rate of reinfection to the point that the previous infection does not seem to protect you. against reinfection, “Dr. Anthony Fauci, a medical advisor to President Joe Biden and longtime director of the National Institute of Allergy and Infectious Diseases, told CNN earlier this month.
What medical research on immunity is telling us right now
Reinfection studies have had proven results so far. (Several projects studying reinfection have recently been announced, including one at the University of Indiana School of Public Health in Bloomington, which evaluates COVID-19 reinfection at U.S. points of interest, and a observational study that plans to evaluate all reinfections reported in France).
A recent preliminary study of marine recruits arriving at a base on Parris Island, South Carolina, found that a previous SARS-CoV-2 infection protected them from reinfection, but only to a certain extent. point. The researchers concluded that sailors with lower IgG antibody titers and neutralizing antibodies had a higher risk of reinfection.
Other research highlights the rarity of reinfection. Researchers in Qatar found that less than 1% of the approximately 44,000 people who had recovered from a case of COVID-19 contracted SARS-CoV-2 for the second time.
But beyond the risk of reinfection, there are several factors that can influence immunity to the SARS-CoV-2 virus.
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“Because you don’t know how long immunity will be induced, we have the possibility, as the virus continues to mutate, that it actually mutates to become a cold virus. That’s what we really expect.
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Not all people who contract the virus develop antibodies to it and some people end up with antibody levels that are not high enough to protect them.
It is also unclear how long the antibodies remain. COVID-19 antibodies decline after 60 days in most people, according to a CDC study of front-line health workers in 12 states and another study by the same group in Nashville, Tennessee, although other studies, including a examining healthcare workers in the UK, have indicated that IgG antibodies can last six months or more.
“Because you don’t know how long immunity will be induced, we have the possibility, as the virus continues to mutate, that it actually mutates to become a cold virus,” said Dr. Stanley Perlman, a professor of microbiology. and immunology at the University of Iowa. “That’s what we really expect.”
If this happened, the virus could be cushioned until it simply becomes an annoying cold but no longer deadly. Common colds, which are coronaviruses that have not been eradicated, can provide immunity for up to three years. People infected with SARS or severe acute respiratory syndrome, also coronavirus, had about three years of immunity.
“Sterilizing immunity” is a term used to explain a type of immunity that means people cannot contract either a virus or the disease caused by a virus. This is unlikely to happen with SARS-CoV-2. What experts are now asking, including Perlman, is whether reinfections will cause less severe forms of the disease or be asymptomatic.
“That could be what’s happening with people who have mild illnesses and are re-infected with serious illnesses,” Perlman said. “I think the protection is much longer. So if someone leaves an ICU and it’s normal, I think they’ll be protected for years. “
What we know about reinfection rates in the US
The federal government does not monitor reinfections and therefore the number of reinfection cases in the US is unknown. The CDC website page with information on reinfections was last updated on October 27th.
Some states have shared details about likely or confirmed reinfections on request.
California, for example, lists two confirmed cases of reinfection of the 3.3 million people who tested positive for the virus there, according to the state’s public health department. About 615 people in Colorado meet CDC criteria for reinfection, according to a state spokesman. “That’s a very small percentage of all cases,” which accounts for 0.15% of all cases in Colorado, he said in an email. In Washington state, there are 716 suspected reinfections and one confirmed case.
The first documented case of reinfection in the United States occurred in a 25-year-old man in Reno, Nevada, according to a study published in the medical journal Lancet in October. The individual tested positive in April, had two negative tests in May, and then tested positive again in June.
His case was identified as part of a genomic sequencing program that had been established in Nevada during the pandemic. (The only way to confirm a reinfection is to sequence the two samples to make sure they have different mutations, which occur naturally as the virus spreads from person to person).
“If we observe differences with regard to the first sample in comparison with the original [virus from Wuhan, China] that they are absent from the second … this type of evidence shows that they were different, that they had diverged before they could enter that person, “said Richard Tillett, a biostatistician at the Nevada Institute of Personalized Medicine and co-author of the Lancet Study .
What you need to know about reinfection and vaccines
If SARS-CoV-2 does not go away, reinfection may be more likely, even if the virus changes shape to become less deadly or cause less serious illness.
Vaccine developers like Johnson & Johnson JNJ,
and Modern Inc. MRNA,
they have said they are considering programs to develop COVID-19 booster or vaccines that will be administered regularly in the future.
“Over the next few years, we will get a COVID-19 vaccine just like a flu vaccine,” J&J CEO Alex Gorsky told CNBC on Feb. 9. “We can all imagine a future where we live this, but we can keep science at the pace of the virus.”
As of now, the CDC claims that people who have once been infected with the virus should still be vaccinated, as long as they wait at least two months after a negative test.
The final phase clinical trials of the two authorized vaccines did not study, for the most part, the impact of the vaccines on people who had previously been infected with the virus. But Pfizer Inc. PFE,
with the German partner BioNTech BNTX,
and Moderna told the Food and Drug Administration separately during the regulatory review process that there are “limited” data suggesting that people who have had the virus may be at risk for reinfection and may benefit from vaccination.
“We’ve seen some case reports here and there of people being re-infected,” Dr. Tal Zaks, chief physician at Moderna, said in January during a call to investors. “But in a context of millions of infected people, I don’t think it’s material.”
Some health workers at the Hackensack Meridian Health Hospital system in New Jersey asked administrators if they should be vaccinated if they have already been infected. The short answer is yes, according to Dr. Richard Varga, chief executive of Hackensack’s doctor.
“We’re putting these people on the same PPE,” he said, “because you don’t know exactly how long and how effective their acquired immunity is.”