Medically reviewed by Susan Kerrigan, MD and Marianne Madsen, University of Utah
The World Health Organization has declared COVID-19 “A Global Pandemic.” Much of the world seems to have taken what may seem like drastic steps to prevent the infection of their populations. Much of the reason for this seems to be that so much is unknown about the disease. In fact, it is possible that a patient can spread COVID-19 (the disease caused by a novel coronavirus) even after they have been declared recovered and their symptoms are gone.
Reuters reported that in Japan, a woman working as a tour bus guide became reinfected with COVID-19 and tested positive after having recovered from an earlier infection. Her case highlighted how much is still unknown about the virus even as concerns grow about its global spread.
The Japanese health minister Katsunobu Kato said that the government would need to keep monitoring the condition of those previously discharged, as health experts analyzed the implications of testing positive for the virus even after an initial recovery.
Philip Tierno, Jr., Professor of Microbiology and Pathology at NYU School of Medicine, stated that “Once you have the infection, it could remain dormant and with minimal symptoms, and then you can get an exacerbation if it finds its way into the lungs.” Tierno further said that much remains unknown about the virus. “I’m not certain that this is not bi-phasic, like anthrax,” he said, meaning the disease appears to go away before recurring.
Ebenezer Tumban, a virologist at Michigan Tech University, relates that it is not uncommon for viruses to persist at low levels in the body even after someone recovers from an illness. A small study in China seems to suggest this. The study was conducted in Wuhan, China on four patients who had been treated with the antiviral drug Tamiflu (oseltamivir) after having tested positive for COVID-19. The new study followed four medical professionals ages 30 to 36 years old who developed COVID-19 and who were treated at Wuhan University’s Zhongnan Hospital in China between January 1 and February 15. All of the individuals recovered, and only one was hospitalized during the illness. The patients were considered recovered from COVID-19 and tested negative twice following recovery from their illness. After recovery, the patients were asked to quarantine themselves at home for five days. They continued to undergo throat swabs for COVID-19 after five days for up to 13 days post-recovery. Surprisingly, the results showed that every test between Day 5 and Day 13 was positive for the virus. Although the sample size was extremely small, researchers concluded that “These findings suggest that at least a proportion of recovered patients still may be virus carriers.” In addition, because patients in his study were medical professionals, they were extremely careful to avoid contaminating their close contacts and family members. Testing a broader sample would therefore be necessary. Tumban suggests that findings from his study beg further investigation and stresses that long-term monitoring of recovered patients and their contacts is important in order to gain greater knowledge and understanding of the disease.