By Dr. Megan Culler Freeman, MD, PhD, University of Pittsburgh — The Conversation US — 25 August 2020
A 33-year-old man was found to have a second SARS-CoV-2 infection approximately four-and-a-half months after he was diagnosed with his first, from which he recovered. The man, who showed no symptoms during the second infection, was diagnosed when he returned to Hong Kong after a trip to Spain.
Genetic sequencing confirmed the second infection was a new virus, with 24 nucleotides different from the first isolate — roughly 0.08% difference in genome sequence. This confirms the second infection was not a recurrence of the first. That immunity to endemic coronaviruses that cause common cold symptoms is relatively short-lived suggests reinfection with SARS-CoV-2 might also be possible.
What can we say based on this one case? Only that reinfection seems possible after enough time has elapsed. We do not know how likely or often it is to occur. As we are still learning about how humans develop immunity to SARS-CoV-2 after infection, the author’s recommendation is for continued masking, hand hygiene and distancing practices even after recovery from COVID-19, to protect against the potential for reinfection.