A healthy, 33-year-old man in Hong Kong is now the first person in the world confirmed to have been reinfected by the pandemic coronavirus, SARS-CoV-2—which has currently infected more than 23 million people worldwide.
The man’s first infection was in late March. He reported having a cough with sputum, fever, sore throat, and a headache for three days before testing positive for the virus on March 26. Though his symptoms subsided days later, he was hospitalized on March 29 and remained in the hospital until April 14, when he tested negative for SARS-CoV-2 in two tests taken 24-hours apart.
About 4.5 months later, the man tested positive for the virus again. This time, his infection was caught during entry screening at a Hong Kong airport, as he returned from a trip to Spain, via the United Kingdom, on August 15. Though he had no symptoms, he was again hospitalized. Clinical data showed he had signs of an acute infection, but he remained asymptomatic throughout his time in the hospital.
Researchers decoded the entire genetic sequences of the SARS-CoV-2 viruses isolated from the man in both infections and found that his two infections were caused by clearly different strains of the coronavirus. The first strain looked much like SARS-CoV-2 strains collected in April and March in the United States and England. The second was closely related to strains collected in England and Switzerland in July and August. Overall, there were 24 genetic differences between the two infecting viral strains, including significant differences in the code for the infamous spike protein.
Hong Kong researchers report the case August 24 in a scientific study that was accepted, but not yet published, by the journal Clinical Infectious Disease. A draft version of the accepted study was released to Ars by the University of Hong Kong and a PDF is available HERE. The PDF does not include the study’s three figures, but the University released a phylogenetic tree (Figure 2), which you can see HERE. Ars has requested the other figures and will update this text when they become available.
With tens of millions of cases around the globe that have accumulated over eight months, cases of reinfection are not surprising—or even necessarily concerning. Studies so far have suggested that immune responses to SARS-CoV-2 can be variable, meaning some people may develop stronger, more protective immune responses than others. There is mounting data suggesting that some immune responses can be completely protective against reinfection—at least for some period of time. From this new study, it’s also rather encouraging that the man’s second infection was even milder than the first—it was completely asymptomatic, in fact—hinting at helpful immune…