It is rare for someone to become infected with the coronavirus that causes the disease COVID-19 a second time, but the few confirmed cases of reinfection tell us immunity to the virus is not guaranteed and vaccination should be a regular part of our medical treatment. could be. take care ahead.
There are approximately 50 confirmed cases of reinfection worldwide. That is far less than 1% of the 110 million coronavirus cases reported worldwide. BNO Nieuws, a Dutch news site, follows re-infections at a global level; it has identified 51 confirmed cases of reinfection, along with approximately 11,000 suspected or probable reinfections.
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.
“I don’t think anyone expected that if you had COVID and got over it, you’d never get it again.”
This is no surprise to some doctors with infectious diseases.
“I think everyone expected re-infections to occur sometime well after the initial infection,” said Dr. Bruce Polsky, an infectious disease physician at NYU Langone Hospital on Long Island. “I don’t think anyone expected that if you had COVID and got over it, you’d never get it again.”
The Centers for Disease Control and Prevention define reinfection as a positive COVID-19 test that occurs at least 90 days after an initial positive test. (This is to distinguish from people with persistent “long COVID” symptoms.) The Public Health Authority says re-infection is rare; however, it also says it expects the number of re-infections to increase as the pandemic continues.
“The likelihood of reinfection with SARS-CoV-2 is expected to increase with time after recovery from the initial infection due to waning immunity and possible genetic abnormality,” the CDC said in October.
As the pandemic enters its second year, it could put some of the roughly 27 million people in the US who have already had COVID-19 at risk of getting it again.
The duration of the pandemic coupled with the emergence of the new, more contagious 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 has said the B.1.1.7 strain, confirmed in 1,523 Americans as of Feb. 16, could become the most dominant form of the virus in the US by the end of March. The B.1.351 variant, first identified in South Africa, has been found in 21 people in the US.
“If [B.1.351] becomes dominant, the experience of our colleagues in South Africa indicates that even if you are infected with the original virus, there is a very high rate of reinfection to the point where a previous infection does not seem to protect you from reinfection, ”Dr. . Anthony Fauci, medical adviser to President Joe Biden and long-term director of the National Institute of Allergy and Infectious Diseases, told CNN earlier this month.
What medical research tells us about immunity right now
Studies on reinfection have so far yielded mixed results. (Recently, a number of projects investigating reinfection have been announced, including one at Indiana University School of Public Health in Bloomington evaluating COVID-19 reinfection in U.S. hotspots, and an observational study that plans to review all reported reinfections in France. judge.)
A recent preliminary study examining marine recruits arriving at a base on Parris Island in South Carolina found that previous infection with SARS-CoV-2 protected them from reinfection – but only to an extent. Marines with lower IgG antibody titers and neutralizing antibodies were at greater risk of reinfection, the researchers conclude.
Other research underscores the rarity of reinfection. Researchers in Qatar found that less than 1% of the approximately 44,000 people who recovered from one case of COVID-19 contracted SARS-CoV-2 a second time.
But beyond the risk of reinfection, there are a number of factors that can affect immunity to the SARS-CoV-2 virus.
Since you don’t know how long immunity is induced, we have the possibility that if the virus continues to mutate, it will actually mutate into a cold virus. That’s what we really hope. ‘
Not all people who contract the virus develop antibodies to it, and some people end up with antibody levels that aren’t high enough to protect them.
It’s also unclear how long antibodies linger. COVID-19 antibodies decline in most people after 60 days, according to a CDC study of primary care health professionals in 12 states and another study of the same group in Nashville, Tennessee, although other studies, including a study of health professionals in the United Kingdom , have indicated that IgG antibodies can last for 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 will actually mutate to become a cold virus,” said Dr. Stanley Perlman, professor of microbiology and immunology at the University of Iowa. “That’s what we really hope.”
If this worked out, the virus could be blunted into just a nasty but no longer deadly cold. 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 immunity for about three years.
“Sterilizing immunity” is a term used to explain a type of immunity, meaning that people cannot contract a virus or the disease caused by a virus. That probably won’t happen with SARS-CoV-2. What experts, including Perlman, are now wondering is whether re-infections will cause less severe forms of the disease or be asymptomatic.
“That could very well be what happens to people who have mild illness and become re-infected with serious illness,” Perlman said. “I think the protection is much longer. So if someone comes out of an IC and is otherwise normal, I think they will be protected for years to come. “
What We Know About Re-infection Rates in the US
The federal government does not track re-infections, so the number of re-infections in the US is unknown. The page on the CDC website that provides information on reinfections was last updated on Oct. 27.
Some states have shared details of likely or confirmed reinfections upon request.
California, for example, cites 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 the CDC criteria for reinfection, according to a state spokesperson. “This is a very small percentage of all cases,” accounting for an estimated 0.15% of total cases in Colorado, she said in an email. In Washington State, there are 716 suspected reinfections and one confirmed case.
The first documented case of reinfection in the US occurred in a 25-year-old man in Reno, Nevada, according to a study published in the medical journal Lancet in October. The person 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 set up during the Nevada 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 differences between the first sample and the original [virus from Wuhan, China] that are absent in the second … that proves they were different, that they had diverged before they could enter that person, ” said Richard Tillett, a biostatistician for the Nevada Institute of Personalized Medicine and a co-author of the Lancet study.
What you need to know about reinfection and vaccines
If SARS-CoV-2 does not go away, re-infection may become more likely, even if the virus changes shape to become less deadly or cause less serious illness.
Vaccine developers such as Johnson & Johnson JNJ,
and Moderna Inc. MRNA,
have said they are considering programs to develop COVID-19 boosters or vaccines to be administered regularly in the future.
“For the next few years, we’ll be getting a COVID-19 shot, just like we’ll be getting a flu shot,” J&J CEO Alex Gorsky told CNBC on Feb. 9. “We can all imagine a future in which we live. This, but we can keep science with the virus.”
As of now, the CDC says that once infected with the virus, people should still get vaccinated, as long as they wait at least two months after a negative test.
The late-stage clinical trials for both authorized vaccines have largely failed to investigate the impact of the vaccines on people previously infected with the virus. But Pfizer Inc. PFE,
with German partner BioNTech BNTX,
and Moderna separately told the Food and Drug Administration during the regulatory review process that there is “limited” data to suggest that people who have had the virus are at risk of reinfection and could benefit from vaccination.
“We’ve seen some case reports here and there of people getting reinfected,” said Dr. Tal Zaks, Moderna’s Chief Medical Officer, in a conversation with investors in January. “But in a context of millions getting infected, I don’t think that’s material.”
Some health workers at the Hackensack Meridian Health hospital system in New Jersey asked administrators if they should get vaccinated if they were already infected. The short answer is yes, according to Dr. Richard Varga, Hackensack’s chief physician.
“We put those people in the same PPE,” he said, “because you don’t know exactly how long and how effective their acquired immunity is.”