Researchers from China have discovered that coronavirus patients can be infectious for up to five weeks after they first develop symptoms. Their study found that COVID-19 can live in people’s respiratory tracts for as long as 37 days after they were diagnosed.
Most healthcare experts around the globe have been recommending an isolation period of just two weeks. Both Israel and the city of Beijing, for example, have implemented 14-day quarantines either for citizens returning from abroad (in China’s case) or for all visitors (as is the case for Israel). This means that common medical understanding of how long coronavirus patients and people under investigation of having the virus may be lacking.
In this study, published in The Lancet, doctors from Wuhan and Beijing studied 191 coronavirus patients from two hospitals in Wuhan, the epicenter of the worldwide pandemic. All 191 patients were either discharged or succumbed to the virus by January 31.
The team collected epidemiological, demographic, clinical, laboratory, treatment and outcome data from the patients’ electronic medical records.
Using this data, the researchers found out that viral shedding occurred in all 191 patients for an average of 20 days after diagnosis, with the shortest observed duration of shedding being eight days and the longest being 37 days.
Viral shedding is when the virus is still detectable in the patients, whether it be in the blood, saliva, stool or other forms of organic matter collected by researchers. In the case of The Lancet‘s study, the researchers figured this out after they discovered COVID-19 RNA — the part of the virus that carries genetic information — in respiratory samples from coronavirus patients. They also found that the virus’ RNA was “sustained until death” in people who succumb to the virus.
“Prolonged viral shedding provides the rationale for a strategy of isolation of infected patients and optimal antiviral interventions in the future,” wrote the authors in their study. “This has important implications for both patient isolation decision making and guidance around the length of antiviral treatment.”
This study is just the latest in a slew of research that shows the coronavirus can survive for far longer than common medical understanding would have you believe.
One study, conducted by the government of the United States with the help of other scientists, found that the coronavirus can survive in the air for up to three hours and can stay alive on surfaces of objects for up to three days. Their tests show that the virus can survive on copper objects for up to four hours, on cardboard for a whole day and on plastic and steel surfaces for up to a terrifying 72 hours.
Another study, published by Chinese researchers in The New England Journal of Medicine, found that the coronavirus can incubate in patients for up to 24 days, although the median incubation period is much lower at three days. While the Centers for Disease Control and Prevention (CDC) believes that people are most likely to infect others with COVID-19 when they’re at their sickest, this study opens up the possibility that more people are being infected by asymptomatic patients who are unknowingly spreading the coronavirus due to a lack of awareness of the need to self-quarantine.
The CDC’s findings on the spread of the coronavirus have been supported by a study conducted by German researchers — one of the first coronavirus studies to be conducted by non-Chinese scientists outside of China. This study found that COVID-19 patients “shed” large amounts of the virus even before symptoms appear, meaning that the virus can easily spread to others even while the infected people are only showing minor symptoms such as coughing or fatigue. (Related: German chancellor Merkel warns 70 percent of Germany now at risk of being infected by the coronavirus.)
The Chinese researchers from The Lancet believe that their study provides more evidence that government healthcare departments are correct in their strategies of isolation for people they suspect are infected. However, infectious disease experts around the world may now need to lobby their countries’ officials more intensely about reassessing how long people need to stay in quarantine once they suspect they’re infected after their case has been confirmed and as soon as medical practitioners announce that they’ve reportedly recovered from the virus.
If current medical quarantine practices remain as they are, the number of coronavirus cases around the world may skyrocket due to people not maintaining their imposed periods of isolation for long enough.
This may especially be the case for countries that aren’t well-equipped to handle the outbreak.