�������ýҕ�l

University of Hong Kong scientists claim to have the first evidence of someone being reinfected with the virus that causes COVID-19. Genetic tests revealed that a 33-year-old man returning to Hong Kong from a trip to Spain in mid-August had a different strain of the coronavirus than the one he’d previously been infected with in March, said Dr. Kelvin Kai-Wang To, the microbiologist who led the work. (Marchione, 8/24)

The case raises questions about the durability of immune protection from the coronavirus. But it was also met with caution by other scientists, who questioned the extent to which the case pointed to broader concerns about reinfection. There have been scattered reports of cases of Covid-19 reinfection. Those reports, though, have been based on anecdotal evidence and largely attributed to flaws in testing. (Joseph, 8/24)

The fact that the man had no symptoms the second time suggests his immune system protected him from disease, although it did not stop the reinfection. The fact that the man had no symptoms the second time suggests his immune system protected him from disease, although it did not stop the reinfection. Study author Kwok-Yung Yuen and his colleagues suggest in their paper that herd immunity is unlikely to eliminate covid-19 on its own and that a potential covid-19 vaccine may not provide lifelong immunity to the disease.(Taylor and Eunjung Cha, 8/24)

Doctors have reported several cases of presumed reinfection in the United States and elsewhere, but none of those cases have been confirmed with rigorous testing. Recovered people are known to carry viral fragments for weeks, which can lead to positive test results in the absence of live virus. But the Hong Kong researchers sequenced the virus from both of the man’s infections and found significant differences, suggesting that the patient had been infected a second time. (Mandavilli, 8/24)

The finding does not mean taking vaccines will be useless, Dr. Kai-Wang To, one of the leading authors of the paper, told Reuters. “Immunity induced by vaccination can be different from those induced by natural infection,” To said. “[We] will need to wait for the results of the vaccine trials to see if how effective vaccines are.” (8/24)

Exactly what that finding means is unclear, however. To and his colleagues make some sweeping statements in their paper, parts of which Science has seen. “It is unlikely that herd immunity can eliminate SARS-CoV-2,” the authors write, referring to the idea that the epidemic will peter out once enough people have been infected and become immune. “Second, vaccines may not be able to provide life-long protection against COVID-19.” But it’s too early to draw those conclusions, says Columbia University virologist Angela Rasmussen. “I disagree that this has huge implications across the board for vaccines and immunity,” she wrote in an email, because the patient described in the study may be a rare example of people not mounting a good immune response to the first infection. (Kupferschmidt, 8/24)

The report, if corroborated, is in line with what immunity experts have been telling us is possible with this virus. The most important detail: The man was not symptomatic during his second infection, which shows that his immune system did respond to the virus. “This is no cause for alarm,” Yale immunologist Akiko Iwasaki tweeted about the new results from Hong Kong. “This is a textbook example of how immunity should work.” (Also, as this is a report on a single patient, it can’t tell us how common reinfections like this are.) (Resnick, 8/24)