The medical team described it as “the longest case of anyone being actively infected with SARS-CoV-2 while remaining asymptomatic.”
The woman presented zero symptoms of COVID-19 throughout her prolonged infection but was found to still be shedding virus particles 70 days after her first positive test. This is much longer than previously reported records of around 20 days’ shedding following an initial positive test.
The medical team detected, isolated and tracked the elderly woman who had previously been diagnosed with chronic lymphocytic leukemia (CCL) when a swab test detected coronavirus in her system. She first tested positive for COVID-19 on March 2 after she was admitted to hospital with severe anaemia. She then tested positive a further 13 times despite showing no symptoms.
Previous accounts found people shedding infectious virus material up to 63 days after first becoming symptomatic, but the dearth of symptoms in this case made it particularly worrying.
It adds to a growing body of research which appears to indicate that asymptomatic coronavirus patients with compromised immune systems, such as cancer patients or those undergoing some form of immunosuppressive therapy, appear to shed the virus for far longer than average.
“Although it is difficult to extrapolate from a single patient, our data suggest that long-term shedding of infectious virus may be a concern in certain immunocompromised patients,” the research team wrote in their paper.
To put that in perspective, three million US citizens are classified as having a compromised immune system due to underlying medical conditions and the treatments thereof; these might include transplant and cancer patients, among others.
Previous research into Middle East respiratory syndrome (MERS) and seasonal coronaviruses have also shown that immunocompromised people tend to shed virus particles for an extended period of time.
The major concern with COVID-19 is determining the prevalence of asymptomatic cases, particularly among the immunocompromised, as these might complicate virus mitigation measures over the long term.
“This indicates that, most likely, the infectious virus shed by the patient would still be able to establish a productive infection in contacts upon transmission,” the researchers wrote.
Doctors treating the woman seized the opportunity to study how the virus mutates within the human body of such a long infection and found that, while a variety of viral variants dominated at certain points, none stuck and turnover of mutations was high.
The researchers caution, however, that this is one isolated case and that far more research would be needed to draw more widespread conclusions about persistent viral shedding within immunocompromised Covid-19 patients.