As weeks pass from when the outbreak started, researchers are trying to get a grasp of the functioning of the novel coronavirus, which has infected more than 700.000 people around the globe.

Lixin Xie and Lokesh Sharma worked with a group of colleagues on 16 patients that had been diagnosed with COVID-19, treated and finally released from the Treatment Center of PLA General Hospital in Beijing in late January.

The patients, with a median age of 35.3 years, still had the virus for up to eight days after the symptoms disappeared, according to the study. The researchers took samples from throat swabs and analyzed them, releasing the patients after two consecutive 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 in a statement co-lead author Dr. Sharma, instructor of medicine at Yale School of Medicine. “More severe infections may have even longer shedding times.”

After reporting symptoms such as fever, cough and difficulty breathing, the patients were treated with a group of medications. The incubation period was five days in all patients but one, while the average duration of the symptoms was eight days. At the same time, the number of days patients remained contagious after showing no symptoms ranged from one to eight days.

“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 at the College of Pulmonary and Critical Care Medicine.

Based on their findings, the authors advised fellow researchers and doctors to treat all asymptomatic and recently recovered patients as cautiously as symptomatic ones. They emphasized that they only looked at a reduced number of patients, all of which had milder infects and eventually recovered. It’s a small sample size, but it signals that more information is needed to study the relationship between the symptoms one can have, and the length of the infection.

Further studies would be needed to see if the results are also applicable to more vulnerable patients such as the elderly, the researchers said. At the same time, more 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.

Other studies have also shown important breakthroughs regarding the virus. US researchers recently discovered the coronavirus doesn’t mutate much, meaning a vaccine could last a lifetime, while the FDA is looking at the use of blood from coronavirus survivors as a treatment.

The new study was published in the journal American Journal of Respiratory and Critical Care Medicine.