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 regular part of our medical treatment. care ahead.
There are about 50 confirmed cases of reinfection globally. This is far less than 1% of the 110 million cases of coronavirus reported worldwide. BNO News, a Dutch news site, follows reinfections globally; 51 confirmed cases of reinfection were identified, along with approximately 11,000 suspected or probable infections.
Reinfection is thought to occur when protective antibodies decrease in people who have previously contracted the virus or in people who have contracted the virus without developing antibodies.
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“I don’t think anyone had the hope that if you had COVID and got over it, you would never be able to get it again.”
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For some doctors with infectious diseases, this is not a surprise.
“I think everyone anticipated that there would be reinfections at some point after the initial infection,” said Dr. Bruce Polsky, an infectious disease physician at NYU Langone Hospital on Long Island. “I don’t think anyone had the hope that if you had COVID and got over it, you would never be able to get it again.”
The Centers for Disease Control and Prevention defines reinfection as a positive COVID-19 test that takes place at least 90 days after an initial positive test. (This is to differentiate people with persistent symptoms of “long COVID.”) The public health agency says reinfection is rare; however, it is also said that the number of reinfections is expected to increase as the pandemic continues.
“The likelihood of SARS-CoV-2 reinfection is expected to increase with recovery from the initial infection due to decreased immunity and possibly genetic drift,” the CDC said in October.
As the pandemic moves into its second year, this could put some of the approximately 27 million people in the United States who already had COVID-19 at risk of catching it.
The length of the pandemic, together with the emergence of new, more infectious variants B.1.1.7 and B.1.351, may also put people at risk for a second infection with the SARS-CoV-2 virus. The CDC said strain B.1.1.7, which has been confirmed in 1,523 Americans since 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, was detected in 21 people in the USA
“If [B.1.351] becomes dominant, the experience of our colleagues in South Africa indicates that even if you were infected with the original virus, there is a very high rate of reinfection to the point where the previous infection does not seem to protect you against reinfection. Anthony Fauci, a medical adviser to President Joe Biden and longtime director of the National Institute of Allergy and Infectious Diseases, told CNN earlier this month.
What medical research tells us about immunity right now
Reinfection studies have had mixed results so far. (A number of projects studying reinfection have recently been announced, including one at Indiana University’s Bloomington School of Public Health, which evaluates COVID-19 reinfection in US hotspots, and an observational study that intends to evaluate all reported reinfections in France. .)
A recent preliminary study of marine recruits arriving at a base on Parris Island in South Carolina found that previous SARS-CoV-2 infection protected them from reinfection – but only to a certain extent. The researchers concluded that sailors with lower titers of IgG antibodies 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 recovered from a COVID-19 case contracted SARS-CoV-2 a second time.
But beyond the risk of reinfection, there are a number of factors that can influence immunity to the SARS-CoV-2 virus.
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“Because you do not know how long the immunity will be induced, we have the possibility that the virus will continue to move because it actually moves to become a cold virus. That’s what we really hope for.
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Not all people who contract the virus develop antibodies against it, and some people end up with levels of antibodies that are not high enough to protect them.
It is also unclear how long the antibodies will stick. COVID-19 antibodies decline after 60 days in most people, according to a CDC study of health care workers in 12 states and another study by the same group in Nashville, Tennessee, although other studies, including one examining health care 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 that the virus will continue to mutate to actually become a cold virus,” said Dr. Stanley Perlman, a professor of microbiology and immunology at the University of Iowa. “That’s what we’re really hoping for.”
If this happens, the virus could be attenuated until it simply becomes a common cold, but no longer deadly. Common colds, which are coronaviruses that have not been eradicated, can provide immunity for up to three years. People who were infected with SARS or severe acute respiratory syndrome, also a coronavirus, had immunity for about three years.
“Sterilizing immunity” is a term used to explain a type of immunity that means that humans cannot contract any virus or disease caused by a virus. Most likely it will not 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 happens to people who have mild illnesses and are re-infected with severe illnesses,” Perlman said. “I think the protection is much longer. So if someone comes out of an intensive care unit and it’s otherwise normal, I think they’ll be protected for years. ”
What do we know about reinfection rates in the US
The federal government does not monitor reinfections, so the number of reinfection cases in the US is unknown. The page on the CDC’s information on reinfections was last updated on October 27th.
Some states have provided details of probable or confirmed reinfections upon request.
California, for example, lists two confirmed cases of reinfection out of 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 the CDC’s criteria for reinfection, according to a state spokesman. “This is a very small percentage of all cases,” accounting for about 0.15 percent of all cases in Colorado, she said in an email. In Washington state, there are 716 suspected infections and a confirmed case.
The first documented case of reinfection in the United States occurred in a 25-year-old man from Reno, Nevada, according to a study published in the Lancet medical journal 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 was established in Nevada during the pandemic. (The only way to confirm a reinfection is to sequence both samples to make sure they have different mutations, which occur naturally as the virus spreads from person to person.)
“If we look at the differences from the first sample to the original [virus from Wuhan, China] which are absent from the second … this kind of proves that they were different, that they diverged, before they could get into that person, “said Richard Tillett, a biostatistician at the Nevada Institute of Personalized Medicine and co-author of the study. Lancet.
What to know about reinfection and vaccines
If SARS-CoV-2 does not go away, reinfection may become more likely, even if the virus changes shape to become less lethal or to cause less severe disease.
Vaccine developers such as Johnson & Johnson JNJ,
and Modern Inc. MRNA,
said they are considering development programs for COVID-19 stimulants or vaccines that are regularly administered in the future.
“Over the next few years, we will receive a COVID-19 vaccine just as we will receive an influenza vaccine,” Alex Gorsky, CEO of J&J, told CNBC on February 9th. “We can all imagine a future in which we live, but we can keep science in the rhythm of the virus. ”
From now on, the CDC says that people who have been infected with the virus should be vaccinated as long as they wait at least two months after a negative test.
Late stage clinical trials for both licensed vaccines have largely not studied the impact of vaccines on people who have previously been infected with the virus. Dar 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 is “limited” data suggesting that people who have had the virus may be at risk for reinfection and could benefit from vaccination.
“We’ve seen several case reports here and there about people getting infected,” Dr. Tal Zaks, Moderna’s chief physician, said in January during an investor call. “But in a context where millions of people are getting infected, I don’t think that’s significant.”
Some hackers at Hackensack Meridian Health in New Jersey asked administrators if they should be vaccinated if they were already infected. The short answer is yes, according to Dr. Richard Varga, chief executive of Hackensack.
“We put those people in the same PPE,” he said, “because you don’t know exactly how long and how effective the acquired immunity is.”