A Spanish health-care worker can now lay claim to a rather unwelcome record as the person fastest to be reinfected with COVID-19. The 31-year-old woman contracted the virus twice within 20 days, according to researchers, who will present their findings this weekend at the European Congress of Clinical Microbiology & Infectious Diseases in Portugal, per CNBC. They say it's the shortest-known gap between infections anywhere in the world. It's important to note, however, that the woman is among the rare few who underwent whole genome sequencing, which confirmed the two distinct infections.
The woman—who was fully vaccinated and received a booster dose on Dec. 8—received a positive result on a PCR test on Dec. 20, per the Guardian. Showing no symptoms, she isolated for 10 days, then returned to work. But by Jan. 10, she had fallen ill with a fever and cough and tested positive again. Researchers say whole genome sequencing showed she had first been infected with delta, followed by the more contagious omicron variant. "This case highlights the potential of the omicron variant to evade the previous immunity acquired either from a natural infection with other variants or from vaccines," says case study author Dr. Gemma Recio of the Institut Català de la Salut in Tarragona.
UK health officials say almost 900,000 people have been potentially reinfected with COVID-19 up to the beginning of April, with 11% of current cases classified as reinfections, per the BBC. But the UK only recognizes reinfections with two positive tests taken at least 90 days apart, given signs that a single infection can result in a positive test results months down the line. This case study indicates that framework is too strict. The CDC also uses the 90-day framework, though it recently described 10 genetically confirmed reinfections within an average of 54 days, per New Atlas. The shortest gap among the cases, separating delta and omicron infections in an unvaccinated teenager, was 23 days. (Read more COVID-19 stories.)