Researchers in the Netherlands have reported a worrying first: A woman has died after being infected with COVID-19 twice, CNN reports. The 89-year-old had a compromised immune system due to the cell-depleting therapy she was receiving for a rare kind of bone marrow cancer, but researchers say the treatment doesn't "necessarily result in life-threatening disease" and the "innate immune response" can be enough to eliminate the virus, per Fox News. The researchers say the woman tested positive for COVID-19 after being hospitalized with symptoms earlier this year, and was released five days later after symptoms receded. She developed symptoms again around two months later, days after she began chemotherapy, and died eight days after testing positive for a second time.
There were no negative tests between the two positive ones, but the Dutch researchers say samples from both tests revealed that the genetic makeup of the viruses was different, suggesting it was a reinfection, not a prolonged case. "The implications of reinfections could be relevant for vaccine development and application," the researchers wrote in the Lancet Infectious Diseases journal. "From a public health perspective, all individuals—whether previously diagnosed or not—must take identical precautions to prevent infection." They added that "further work is needed to assess immune reactions in vitro after reinfection." (The US has confirmed its first known reinfection case.)