AP – Evidence is growing that COVID-19 may not be able to be protected again against some of the new variants. Humans can also get second-hand infections with earlier versions of the coronavirus if they first put up a weak defense, new research suggests.
How long immunity lasts against natural infection is one of the big questions in the pandemic. Scientists still think that reinfections are fairly rare and usually less serious than initial, but recent developments around the world have raised concerns.
In South Africa, new infections with a variant were found in two percent of the people who previously had an earlier version of the virus.
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In Brazil, several similar cases with a new variant have been recorded there. Researchers are investigating whether re-infections help explain a recent boom in the city of Manaus, where presumably three-quarters of the residents were previously infected.
In the United States, a study found that 10% of Marine recruits who had evidence of previous infection and repeatedly tested negative before starting basic training were later re-infected. The work was done before the new variants began to spread, said one study leader, Dr. Stuart Sealfon, of the Icahn School of Medicine on Mount Sinai in New York.
“Previous infection does not give you a free pass,” he said. A significant risk of reinfection remains. ‘
Re-infections are a healthcare concern, not just a personal one. Even in cases where reinfection causes no symptoms or merely mild symptoms, people can still spread the virus. This is why health officials insist on vaccination as a long-term solution and encourage people to wear masks, keep physical distance and wash their hands regularly.
“It’s an incentive to do what we ‘ve been saying all along: to vaccinate as many people as we can and to do it as quickly as possible,” said Dr. Anthony Fauci, the U.S. government’s leading expert in infectious diseases, said.
“If I look at the data, it indicates … and I want to underline, suggests that the protection provided by a vaccine may be even a little better” than natural infection, Fauci said.
Doctors in South Africa became concerned when they saw a surge of cases in areas where blood tests indicated that many people already had the virus late last year.
Illustrative. Thabisle Khlatshwayo receives her second shot at AstraZeneca in Soweto’s Chris Sani Baragwanath Hospital outside Johannesburg, South Africa, on 30 November 2020. (AP Photo / Jerome Delay)
Until recently, all indications were ‘that previous infection provided protection for at least nine months’, so a second wave should have been’ relatively muted ‘,’ said Dr. Shabir Madhi of the University of the Witwatersrand in Johannesburg said.
Scientists have discovered a new version of the virus that is more contagious and less susceptible to certain treatments. It now causes more than 90% of new cases in South Africa and has spread to 40 countries, including Israel and the United States.
Madhi led a study that tested the vaccine of Novavax and found it to be less effective against the new variant. The study also revealed that infections with the new variant were just as common among people who had COVID-19 as those who did not.
“What this basically tells us is, unfortunately, that the infection in the past with early variants of the virus in South Africa did not protect against the new,” he said.
In Brazil, an increase in hospitalizations in Manaus in January caused similar concern, revealing a new variant that is also more contagious and less vulnerable to some treatments.
“Re-infection can be one of the drivers for these cases,” said Dr. Ester Sabino of the University of Sao Paulo said. She wrote an article in Lancet magazine about possible explanations. “We have not yet been able to determine how often this happens,” she said.
Scientists in California are also investigating whether a newly identified variant could cause re-infections or a resurgence in cases there.
“We’re looking at it now,” blood samples from previous cases looked for, “said Jasmine Plummer, a researcher at Cedars-Sinai Medical Center in Los Angeles.
Dr. Howard Bauchner, editor-in-chief of the Journal of the American Medical Association, said it would soon report on what he calls “the Los Angeles variant.”
New variants were not responsible for the reinfections seen in the study of Marines – this was done before the mutated viruses emerged, says Sealfon, who led the work with the Naval Medical Research Center. Other findings from the study were published in the New England Journal of Medicine; the news about reinfection is posted on a research website.
Israelis receive a COVID-19 vaccine at a sports hall converted into a Clalit Health vaccination center in Hod Hasharon, on February 2, 2021. (Miriam Alster / Flash90)
The study involved several thousand marine recruits who tested negative for the virus three times during a two-week military quarantine under supervision before beginning basic training.
Of the 189 whose blood tests indicated that they had been infected in the past, 19 tested positive again during the six weeks of training. This is much less than those without a previous infection – “almost half of them became infected at the basic training site,” Sealfon said.
The quantity and quality of antibodies previously infected by Marines was linked to their risk of contracting the virus again. No reinfections caused serious illness, but that does not mean the recruits were not in danger of spreading infection to others, Sealfon said.
‘It does seem that re-infection is possible. “I do not think we fully understand why it is and why immunity has not developed”, said an expert immunologist, who had no role in the study, E. John Wherry of the University of Pennsylvania.
“Natural infections can leave you with a variety of immunities,” while vaccines consistently cause high levels of antibodies, Wherry said.
“I’m optimistic that our vaccines will go a little better.”