The novel coronavirus that causes COVID-19 has impacted millions of people worldwide. Roughly one-third of the world is under some sort of lockdown because of the spread of the virus. There are new cases daily and the virus has been deadly to thousands of people. What researchers find puzzling is that many infected people show no symptoms, meaning they are asymptomatic carriers.
Asymptomatic transmission is one of the primary reasons that COVID-19 has spread so rapidly. People can be contagious and not know it, according to Dr. William Schaffner, professor of preventative medicine and infectious diseases at Vanderbilt University Medical Center. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, suggests that about 25% to 50% of people with COVID-19 never show symptoms or fall ill. Asymptomatic carriers, however, are not unique to COVID-19.
Viral or bacterial infections typically have a spectrum of not sick at all to modestly sick to very sick. That is what health experts know about asymptomatic carriers of COVID-19 at this time. Researchers are hard at work to figure out how long asymptomatic carriers can be contagious. This is not an easy riddle to solve, but the best advice that researchers can give at the moment is for every person to act as though he/she is a carrier of the virus. This means following social distancing orders and wearing masks in essential businesses or communal areas.
Were Asymptomatic Carriers Always Around?
In the New England Journal of Medicine, Bill Gates wrote that global containment efforts of COVID-19 would be much harder with asymptomatic transmission. This was not the case for severe acute respiratory syndrome (SARS), which spread much less efficiently. The World Health Organization’s report about the coronavirus outbreak in China, which was published in February 2020, found few instances that showed asymptomatic patients. In fact, about 75% of people in China who tested positive without symptoms developed symptoms later on.
What About Presymptomatic Transmission?
Several studies confirm that people who test positive do not show symptoms on the day of diagnosis. The coronavirus has a two to 14-day incubation period, meaning that people can transmit the virus unknowingly before developing symptoms, also referred to as presymptomatic transmission. Another study confirmed that many people are shedding the virus 48 hours before symptoms appear.
The combination of asymptomatic and presymptomatic transmitters helps to explain how the virus spreads so rapidly. More recent studies suggest that this is not unusual.
- The Los Angeles Times reported that 75% of a group of singers at a 60-person choir practice got COVID-19, despite the fact that none of the members showed symptoms at practice.
- A biotech company in Iceland tested more than 9,000 people. The test results indicated that about 50% of people who tested positive were asymptomatic.
- The New England Journal of Medicine published a report on April 13th, 2020. This report examined coronavirus infections in pregnant women giving birth at two New York City hospitals between March 22, 2020, and April 4th, 2020. Of the 215 women who were tested for COVID-19, 33 women tested positive and only four showed symptoms.
- New research shows that COVID-19 patients continue to shed the virus for several days after symptoms clear.
The only way to learn more about the virus is to conduct more studies. Even if you think that you don’t have COVID-19, please take preventative measures to avoid continued transmission. Let’s do all that we can to stop the spread by abiding by rules that are set in place. Keep your distance, wear masks, wash your hands, and don’t forget that kindness is key in times like these.