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 can become a regular part of our doctor. be careful from now on.
There are about 50 confirmed cases of reinfection worldwide. This is much less than 1% of the 110 million cases of coronavirus reported worldwide. BNO News, a Dutch news site, is monitoring reinfections globally; 51 confirmed cases of reinfection have been identified, along with about 11,000 suspected or probable reinfections.
Reinfection occurs when protective antibodies decrease in people who have contracted the virus or who have contracted the virus without developing antibodies.
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– I don’t think anyone expected that if you had COVID and got over it, you would never be able to catch it again.
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For some infectious disease doctors, this is not surprising.
“I think everyone predicted that there would be reinfections at some distant point after the initial infection,” said Dr. Bruce Polsky, an infectious physician at NYU Langone Hospital on Long Island. “I don’t think anyone expected that if you had COVID and got over it, you would never be able to catch it again.”
The Center for Disease Control and Prevention defines reinfection as a positive COVID-19 test that occurs at least 90 days after an initial positive test. (This is to differentiate from people with persistent “long COVID” symptoms.) The public health agency says reinfection is rare; however, it also says that it 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,” said the CDC in October.
As the pandemic enters its second year, this could put some of the nearly 27 million people in the United States who have had COVID-19 at risk of catching it again.
The duration of the pandemic, together with the emergence of the new B.1.1.7 and B.1.351 variants, which are more infectious, can also put people at risk of a second infection with the SARS-CoV-2 virus. The CDC said that the B.1.1.7 strain, which was confirmed in 1,523 Americans on February 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] it 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 appear to protect you from reinfection ” , Anthony Fauci, medical consultant to President Joe Biden and longtime director of the National Institute of Allergy and Infectious Diseases, told CNN earlier this month.
What medical research is telling us about immunity now
Studies on reinfection have had mixed results so far. (Several reinfection study designs were recently announced, including one at the Indiana University School of Public Health in Bloomington evaluating COVID-19 reinfection at critical points in the U.S. and an observational study that plans to evaluate all reported reinfections in France. )
A recent preliminary study that examined recruits from the Marines arriving at a base on Parris Island, South Carolina, found that previous SARS-CoV-2 infection protected them from reinfection – but only to a degree. Marines with lower IgG antibody titers and neutralizing antibodies are at increased risk of reinfection, the researchers concluded.
Another study 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.
However, in addition to the risk of reinfection, there are a number of factors that can influence immunity to the SARS-CoV-2 virus.
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‘Since you don’t know how long immunity will be induced, we have the possibility that, as the virus continues to mutate, it will actually change to become a cold virus. This is 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 remain. COVID-19 antibodies decrease after 60 days in most people, according to a CDC study of frontline healthcare professionals in 12 states and another study by the same group in Nashville, Tennessee, although other studies, including one examining Health care professionals in the UK have indicated that IgG antibodies can last six months or more.
“Since you don’t know how long immunity will be induced, we have the possibility, as the virus continues to mutate, that it actually changes to become a cold virus,” said Dr. Stanley Perlman, professor of microbiology and immunology of the University of Iowa. “This is what we really hope for.”
If that happened, the virus could be cushioned until it simply became a common irritating, but not deadly, cold. 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 a coronavirus, had about three years of immunity.
“Sterilizing immunity” is a term used to explain a type of immunity that means that people cannot contract a virus or the disease caused by a virus. It is very likely that this will not happen with SARS-CoV-2. What experts, including Perlman, are wondering is whether reinfections will cause less severe forms of the disease or be asymptomatic.
“This may well be what is happening to people who have a mild illness and are reinfected with serious illnesses,” said Perlman. “I think the protection is much longer. So, if someone leaves an ICU and it is normal, I think they will be protected for years. “
What we know about reinfection rates in the US
The federal government does not screen for reinfections and, therefore, the number of cases of reinfection in the USA is unknown. The page on the CDC website with information on reinfections was last updated on 27 October.
Some states shared details of likely or confirmed reinfections upon request.
California, for example, lists two confirmed cases of reinfection among 3.3 million people who test positive for the virus, 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,” making an estimate of 0.15% of total cases in Colorado, she said in an email. In the state of Washington, there are 716 suspected reinfections and a 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 established in Nevada during the pandemic. (The only way to confirm a reinfection is to sequence the two samples to ensure that they have different mutations, which occur naturally as the virus spreads from person to person.)
“If we look at the differences in the first sample compared to the original [virus from Wuhan, China] who are absent from the second … it proves that they were different, that they had diverged before they could have entered that person, “said Richard Tillett, a biostatistician at the Nevada Institute of Personalized Medicine and co-author of the Lancet study.
What to know about reinfection and vaccines
If SARS-CoV-2 does not disappear, reinfection may become more likely, even if the virus changes shape to become less deadly or to cause less serious illness.
Vaccine developers like Johnson & Johnson JNJ,
and Moderna Inc. MRNA,
said they are considering programs to develop boosters or COVID-19 vaccines that will be administered regularly in the future.
“In the coming years, we will receive a COVID-19 vaccine, just as we will have a flu vaccine,” Alex Gorsky, CEO of J&J, told CNBC on February 9. “We can all imagine a future in which we live this, but we can keep science in step with the virus. “
As of now, the CDC says that people who were once infected with the virus should still be vaccinated, as long as they wait at least two months after a negative test.
Advanced clinical trials for both authorized vaccines have not, for the most part, studied the impact of vaccines on people who had previously been infected with the virus. But Pfizer Inc. PFE,
with the German partner BioNTech BNTX,
and Moderna, separately, told the Food and Drug Administration during the regulatory review process that there is “limited” data suggesting that people who have had the virus may be at risk of reinfection and may benefit from vaccination.
“We saw some case reports here and there of people being reinfected,” said Tal Zaks, Medical Director at Moderna, in January, during a call with investors. “But in the context of millions of infected people, I don’t think this is relevant.”
Some healthcare professionals from the Hackensack Meridian Health hospital system 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 medical officer at Hackensack.
“We are putting these people on the same PPE,” he said, “because you don’t know exactly how long and how effective the acquired immunity is.”