Spanish researchers say a 31-year-old woman has tested positive for COVID twice within 20 days.
According to a statement by the European congress of clinical microbiology and infectious diseases, the researchers, in a case study, said the period between the infections is the shortest ever recorded.
They said the woman, who is a healthcare worker, first tested positive on December 20, 2021, after taking a PCR test during staff screening at her place of work and self-isolated for 10 days before returning to work.
She was said to have tested positive for the virus again on January 10, 2022, after developing a cough, and a fever.
The health worker is reportedly fully vaccinated and received a booster shot 12 days before the first infection.
The researchers said whole genome sequencing showed that the woman had been infected by two different strains of COVID-19 — the first infection was due to the Delta variant, while the second, the Omicron variant.
Gemma Recio, one of the study’s authors, said the case highlights the potential of the Omicron variant to evade the immunity gotten either from a natural infection with other variants or from vaccines.
“In other words, people who have had COVID-19 cannot assume they are protected against reinfection, even if they have been fully vaccinated. Nevertheless, both previous infection with other variants and vaccination do seem to partially protect against severe disease and hospitalisation in those with Omicron,” Recio said.
“This case also underscores the need to carry out genomic surveillance of viruses in infections in those who are fully vaccinated and in reinfections. Such monitoring will help detect variants with the ability to partially evade the immune response.”