Israeli doctors are investigating 81 cases of COVID-19 patients who appear to have recovered from the coronavirus and later became reinfected.
A Health Ministry spokeswoman told The Times of Israel that the figure, first publicized by Army Radio, is accurate, though she did not provide more details. The cases are still being probed, and officials believe that the final confirmed number of reinfections may be smaller.
Israel is believed to be the first country in the world to confirm such a large-scale investigation into reinfection.
The revelation comes as an Israeli reinfection case was, for the first time, documented in formal medical research.
“I didn’t believe it at first when she tested positive,” the patient’s doctor, Vered Nachmias, told The Times of Israel, saying she suspects that reinfection is more common than physicians realize.
Scientists currently believe that fewer than two dozen people worldwide have been confirmed reinfected, and the British medical journal Lancet put the figure as low as five in its latest report.
The Lancet article, published Monday, put the issue of reinfection on the global health agenda, as it documented America’s first confirmed case of SARS-CoV-2 reinfection.
Then on Tuesday, Dutch authorities reported what is believed to be the first death as a result of reinfection. The deceased is an 89-year-old immunocompromised woman, who tested positive, recovered, and 59 days later fell ill and once again tested positive.
She did not have negative tests between illnesses, but researchers reportedly said that the genetic makeup of the virus found in the tests differed, suggesting it was reinfection and not a single prolonged illness.
Since the start of the pandemic, doctors have been asking whether infection will confer immunity, and if so how long it will last. They have also been asking whether immunity could be undermined by small mutations that are seen in the virus — a development that could pose challenges for vaccine efficacy.
In the American case outlined in the Lancet, the patient was a 25-year-old man from Nevada, who had no known immune disorders. Many medical professionals had assumed that, if people are reinfected, they will experience milder symptoms.
This proved correct with the documented Israeli patient, who had mild symptoms the first time around and, upon second infection, was asymptomatic with the exception of an elevated heart rate. However, Lancet reported that with the American patient, “what is worrisome is that SARS-CoV-2 reinfection resulted in worse disease than did the first infection, requiring oxygen support and hospitalization.”
The confirmed Israeli case was documented, peer-reviewed and published by Nachmias and colleagues from the Leumit health organization in the journal IDCases.
They told the story of a 20-year-old woman from Bnei Brak, healthy until she caught the coronavirus. She was diagnosed on April 17, and tested negative on May 1 and May 10.
The doctors wrote: “During the first week of August 2020, after enjoying three months of health, some of her family members were symptomatic for COVID-19 and tested positive.” The patient then went for screening on August 6 and on August 11, and tested positive both times.
Asked how sure she is about the reinfection diagnosis, Nachmias told The Times of Israel: “There is no room for doubt, there was clearly reinfection. We did the first tests while she was diagnosed to have the disease clinically, then she was clearly negative, and she was subsequently infected.”
She said that upon the second infection, she had a blood sample drawn for analysis and found that antibodies were present. As most patients wouldn’t yet have antibodies so soon after infection, Nachmias said they were seemingly from the first infection, constituting extra evidence that the patient had, indeed, been infected back in April.
Nachmias said that she doesn’t have an explanation for what went wrong to result in the reinfection, but she raised the fear of a changing virus that would undermine immunity.
“I’m worried about a mutation,” Nachmias said. “Maybe she had a mutation of the virus and not exactly the same virus.”
Bar Ilan University immunologist Cyrille Cohen thinks the mutation theory is unlikely. He thinks that despite the revelation of the 81 suspected reinfection cases in Israel, and the documenting of several incidences internationally, cases are still so rare that they reflect exceptions that prove the rule of immunity.
“It’s a fact, it’s undeniable, that we are seeing immunity” he said. “If it wasn’t the case, and there wasn’t generally immunity after infection, we would’ve seen lots of people getting the coronavirus and then getting it again.”
He said that SARS-CoV-2 appears to result in immunity, with some rare exceptions, which isn’t unusual as infections from the coronavirus family go.
“There is no such thing as 100% immunity, with reinfection by viruses generally possible,’ Cohen commented.
But Nachmias suspects reinfection is being underdiagnosed by doctors who simply don’t test recovered patients because they assume immunity.
“I think it isn’t so rare and may be underdiagnosed, with doctors telling patients they don’t need to be tested for coronavirus if they have had the disease,” she said.
Tel Aviv University professor Mordechai Gerlic told The Times of Israel he suspects that mistakes account for some reports of reinfection, saying they diagnoses may well reflect testing errors, or patients who never fully recovered from their first infection.
Confirmed cases should not cause alarm, he said. “In any biological system you have outliers, and the statistics here prove it’s not something to worry about.”