According to a recent study published in the Annals of Internal Medicine, atleast one in three COVID-19 infection are asymptomatic. The study reviewed 61 studies and reports of which 43 used PCR testing of the nasopharyngeal swabs to detect the current SARS CoV-2 infection and 18 studies used antibody testing to detect the current or prior infection. The study included observational, descriptive studies and reports of mass screening for SAR CoV-2 (cross sectional or longitudinal in design) published through November 2020.
According to the study, infected people without symptoms – both presymptomatic and asymptomatic – account for more than 40% of all SARS CoV-2 transmission. As per the study, the highest-quality evidence comes from nationwide, representative serosurveys of England (n = 365 104) and Spain (n = 61 075), which suggest that at least one third of SARS-CoV-2 infections are asymptomatic.
Source: The Annals of Internal Medicine
A serosurvey is the collection and testing of blood (or proxy specimen) from individuals of a defined population over a specific period to estimate the prevalence of IgG antibodies. The presence of IgG antibodies serve as an indicator of exposure, disease burden and immunity towards the infection.
