Asymptomatic COVID-19 May Not Be As Common As You Think

In order to track prevalence rates of COVID-19 infections, health officials require knowledge of the virus' transmissibility in order to safeguard against community outbreaks (via JAMA Network). For this reason, scientists have been examining cases of both symptomatic and asymptomatic individuals since the start of the pandemic. In a 2020 study published in the International Journal of Infectious Diseases, researchers outlined the nature of COVID-19 to be "unpredictable," with symptoms varying in severity from pneumonia and respiratory distress, to no symptoms whatsoever.

Tracking COVID-19 rates proves more difficult with asymptomatic cases, as asymptomatic individuals infected with COVID-19 might not voluntarily seek out testing unless they detect symptoms. For this reason, researchers have been studying just how common asymptomatic cases are amongst the public. In a 2021 scientific analysis of over 90 COVID-19 studies containing data from more than 20 million COVID-19 tested individuals, researchers found that asymptomatic infections accounted for 0.25% of the total tested population and just over 40% of those with confirmed COVID-19 infections (via JAMA Network).

While these numbers appear to indicate a high prevalence of asymptomatic cases, new research has found that asymptomatic COVID-19 cases may not be so rampant after all.

In a recent study published in Open Forum Infectious Diseases, researchers examined the rates of asymptomatic COVID-19 infection among 263 unvaccinated "immunocompetent" healthcare workers. With a combined average age of 41, participants engaged in routine antibody testing every month, as well as PCR testing whenever they experienced any of the 34 COVID-19-related symptoms that researchers outlined in categories, such as nasal, throat, chest, gastrointestinal, taste, or smell, amongst others.

The study was conducted between August 25, 2020, and February 28, 2021 (via Open Forum Infectious Diseases). Within that time, 12 out of the total 263 participants tested positive for COVID-19, all of whom experienced some degree of symptoms approximately around the time of infection. Dr. Edward Mitre, a senior author of the study, noted that if asymptomatic COVID-19 cases were as prevalent as previous research indicated, the chances of all 12 out of the COVID-19 cases experiencing symptoms would've been "very unlikely" (via HealthDay).

"Even if the true rate of asymptomatic infection is 30%, then the likelihood that 12 of 12 individuals would all be symptomatic is still only 1.4%," Dr. Mitre told HealthDay. However, researchers openly acknowledge the limitations of the study, as research was solely conducted on unvaccinated individuals. Researchers also point out that self-detection of COVID-19-related symptoms amongst participants may have been higher due to the fact that participants were on high alert for signs of infection.