In this study, 50% of patients tested positive for coronavirus after recovery in the hospital and two weeks of isolation. They were found to still have the coronavirus in their system for up to eight days after symptoms disappeared.

As the number of 2019 novel coronavirus cases increase, many health officials have recommended people to stay at home as much as possible. People who are sick or with mild symptoms of COVID-19 are advised to isolate themselves for two weeks at home until symptoms disappear. Patients with more severe and life-threatening cases of COVID-19 can be treated in isolation at a hospital until they recover. Despite these warnings, the novel coronavirus continues to spread worldwide. One reason might be because we haven’t determined when a person is virus-free. Is COVID-19 truly gone after our symptoms disappear? A team of doctors from Beijing, China and researchers at Yale worked together to find this answer. Their research was published in the American Journal of Respiratory and Critical Care Medicine.

The researchers looked at how long the virus stays in the system and if it disappears the same time our symptoms go away. The study involved sixteen patients who were treated at the Treatment Center of PLA General Hospital in Beijing, China for mild infections of COVID-19. Patient ages varied from three years up to sixty-eight years old. In addition, two out of the sixteen patients had diabetes and one out of the sixteen had tuberculosis. Patients were treated for symptoms including fever, cough, sore throat, and shortness of breath. Patients also received different types of medical care depending on the severity of their symptoms.

Patients were swabbed in the throat and tested every other day for any signs of the novel coronavirus. Between January 28th and February 9th, patients were discharged when they appeared to recover and tested negative for the virus. Only one patient who was initially cleared had to be called back because the test made a mistake. This patient was confirmed to be negative for the virus after conducting two more tests. Patients considered disease-free were strongly advised to stay at home for two weeks and to follow-up with the hospital one week after that to test that they were still negative.

The research data showed that the incubation time—time from infection to the onset of symptoms—varied for each patient. The incubation period was based on the patient’s travel history and/or direct contact with a person with COVID-19. In this study, ten people were found to be sick after visiting Wuhan, China, three were from an infected person, two people were sick after coming into contact with people from Wuhan, and one person became sick from an unknown origin. Based on these findings, the study authors estimated that it took an average of five days for patient symptoms to appear after getting the novel coronavirus. It also took an average of eight days for the sixteen patients to start showing COVID-19 symptoms.

The one week follow-up visit showed eight out of the sixteen patients still had the novel coronavirus—even when no symptoms were observed. Patients who had tested positive for the novel coronavirus remained positive anywhere from one to eight days after symptoms disappeared.

The research results are important in helping us prevent the spread of the 2019 novel coronavirus. This study showed half of the patients who recovered from COVID-19 still had the novel coronavirus in their body for up to eight days after symptoms disappeared. This also holds true for children as a three year old boy was still positive for COVID-19 after leaving the hospital. With this in mind, the study authors concluded that newly recovered patients with no symptoms should still be treated as carefully as patients with symptoms.

In an American Thoracic Society press release, one of the authors Dr. Lixin Xie recommended staying at home as the best solution to contain the virus. “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.”