You can still pass on COVID-19 up to eight days after you think you've recovered
American Thoracic Society
In a new study, researchers found that half of the patients they
treated for mild COVID-19 infection still had coronavirus for up to eight days
after symptoms disappeared. The research letter was published online in the
American Thoracic Society's American Journal of Respiratory and
Critical Care Medicine.
In "Time Kinetics of Viral Clearance and Resolution of
Symptoms in Novel Coronavirus Infection," Lixin Xie, MD, Lokesh Sharma,
PhD, and co-authors report on a study of 16 patients with COVID-19, who were
treated and released from the Treatment Center of PLA General Hospital in
Beijing between January 28 and Feb. 9, 2020. Patients studied had a median age
of 35.5 years.
Researchers collected samples from throat swabs taken from all
patients on alternate days and analyzed. Patients were discharged after their
recovery and confirmation of negative viral status by at least two consecutive
polymerase chain reaction (PCR) tests.
"The most significant finding from our study is that half of the patients kept shedding the virus even after resolution of their symptoms," said co-lead author Dr. Sharma, instructor of medicine, Section of Pulmonary, Critical Care & Sleep Medicine, Department of Medicine, Yale School of Medicine. "More severe infections may have even longer shedding times."
The primary symptoms in these patients included fever, cough,
pain in the pharynx (pharyngalgia) and difficult or labored breathing
(dyspnea). Patients were treated with a range of medications.
The time from infection to onset of symptoms (incubation period) was five days among all but one patient. The average duration of symptoms was eight days, while the length of time patients remained contagious after the end of their symptoms ranged from one to eight days.
Two patients had diabetes and one had tuberculosis, neither of which affected the timing of the course of COVID-19 infection.
"If you had mild respiratory symptoms from COVID-19 and were staying at home so as not to infect people, extend your quarantine for another two weeks after recovery to ensure that you don't infect other people," recommended corresponding author Lixin Xie, MD, professor, College of Pulmonary and Critical Care Medicine, Chinese PLA General Hospital, Beijing.
The authors had a special message for the medical community:
"COVID-19 patients can be infectious even after their symptomatic
recovery, so treat the asymptomatic/recently recovered patients as carefully as
symptomatic patients."
The researchers emphasized that all of these patients had milder
infections and recovered from the disease, and that the study looked at a small
number of patients. They noted that it is unclear whether similar results would
hold true for more vulnerable patients such as the elderly, those with
suppressed immune systems and patients on immunosuppressive therapies.
"Further studies are needed to investigate if the real-time
PCR-detected virus is capable of transmission in the later stages of COVID-19 infection,"
Dr. Xie added.