A man from Nevada has had COVID-19 twice. That’s why we need a vaccine

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If you relied on a coronavirus infection to protect you from COVID-19 without having to get vaccinated, scientists have bad news: it won’t work.Proof of this is a man from Nevada who was infected with two separate versions of the novel coronavirus and who fell ill with COVID-19 both times. In fact, he was sicker the second time around and had to be hospitalized so that doctors could give him extra oxygen to help him breathe.

The unidentified patient is the first confirmed case in North America of someone re-infected with the virus known as SARS-CoV-2, according to a report published Monday in the Lancet Infectious Diseases medical journal.

At first glance, the Nevada man doesn’t appear to be a likely candidate for one case of COVID-19, let alone two. He was young – only 25 – and had no history of underlying medical conditions that would increase his risk of disease, the report’s authors wrote. He was not taking any medication that would suppress his immune system. Blood tests showed he was HIV negative and his cell counts appeared normal, they added.

But on March 25, he began showing a disturbing list of symptoms: sore throat, cough, headache, nausea and diarrhea. By April 18, they had gotten bad enough that he went to a coronavirus testing center run by the Washoe County Health District. The workers obtained a specimen from the back of his nasal cavity. Indeed, it contained genetic evidence of SARS-CoV-2.

The man recovered in isolation at home and his symptoms resolved nine days later. Two follow-up tests on May 9 and 26 confirmed he was negative for coronavirus infection.

This should have been the end of the story. But on May 28, he started to feel sick again.

On May 31, he went to an emergency care center to complain of a fever, headache, dizziness, cough, nausea and diarrhea. He had a chest x-ray and was sent home.

On June 5, he was having trouble breathing and his body was not getting enough oxygen to his tissues. He went to his primary care doctor, who sent him to the hospital. Another chest x-ray indicated he had pneumonia, and he was admitted and treated with supplemental oxygen.

Once again, a nasopharyngeal coronavirus test came back positive.

Was it the same case of COVID-19 or did he have the disease twice?

Novel coronavirus infections are believed to be rare, but have been confirmed in patients in Hong Kong, Belgium and Ecuador. A team led by biostatistician Richard Tillett of the Nevada Institute of Personalized Medicine went to great lengths to see if the Washoe County patient should be added to this list.

The fact that his positive coronavirus tests were spaced 48 days apart was strong evidence that he had indeed been infected twice, Tillett’s team wrote. So was the fact that between these two tests, two more coronavirus tests came out negative.

Still, to cover all their bases, the team performed genetic analysis of the specimens tested on April 18 and June 5. Both were found to belong to the same group, or clade, that was found primarily in North America.

But they weren’t the same. Compared to a reference genome for SARS-CoV-2, the virus that sickened man in April had four specific genetic variants that were not present in the virus that sickened him in May.

Likewise, the virus he caught in May had seven other genetic variants that set him apart from the reference genome but which were not seen in the virus he caught in April. The RNA in the second virus also had three deletions and an insertion that was not seen in the first virus.

Did the virus that infected him in April stay in his body and mutate so much over the next 48 days that he acquired all of these changes by the time he was tested in June? This is extremely unlikely, the researchers wrote.

For this to happen, this coronavirus would need to accumulate around 84 changes per year. This rate “greatly exceeds” the actual rate of about 23 changes per year, they said. And not only should the virus’s RNA have changed at an all-time high, some of the changes in April should have reverted to the original in June.

“The chances of this reversion occurring are low,” they added.

Researchers performed further tests to determine whether the two coronavirus samples were from different patients but were accidentally assigned to the same man. They determined that the odds of this were about 1 in 53,000,000,000,000,000,000,000,000.

The results of all of these tests clearly show that fighting off a COVID-19 infection is not necessarily enough to immunize someone against the coronavirus in the future, wrote Tillett and his colleagues.

What is particularly concerning in the case of the Nevada man is that he was sicker the second time around, wrote Akiko Iwasaki, a viral immunity expert at Yale, in a commentary accompanying the Lancet report on infectious diseases. This is a clear sign that COVID-19 survivors cannot count on being protected if they encounter the coronavirus again.

Some people – including Dr Scott Atlas, a neuroradiologist who sits on the White House Coronavirus Task Force – have argued that instead of using shutdown measures to contain the virus, we should allow him to spread so that people can develop natural immunity. Vaccine skeptics in particular have taken this approach, in some cases attempting to deliberately infect themselves in a strategy reminiscent of the chickenpox festivals of yore.

Experts estimate that when 70% to 80% of the population is immune, the virus will have such a hard time finding new targets to infect that herd immunity will be established and the pandemic will be over. But the new report shows that natural infections will not be enough to get us there, Iwasaki wrote.

“Cases of re-infection tell us that we cannot rely on the immunity acquired through natural infection to confer herd immunity; not only is this strategy deadly for many, it is also not effective, ”she wrote. “Collective immunity requires safe and effective vaccines and robust immunization implementation.”

The good news is that while a person can be infected with two versions of SARS-CoV-2, that doesn’t mean we will need separate vaccines for each of them. At this point, there is no evidence that the Nevada patient fell ill a second time because the coronavirus had learned to evade his immune system’s defenses, Iwasaki wrote.

“For now, a single vaccine will be sufficient to confer protection against all circulating viruses,” she writes.

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