Dr Sartelli notes that, while SARS-CoV-2 is extremely homologous with the previous SARS-CoV outbreak, it has a much higher reproductive number (R0), which must be accounted for somehow. SARS-CoV was not transmissable during the asymptomatic phase of the disease. SARS-CoV-2, however, has been proven to cause asymptomatic transmission, as confirmed by numerous contact tracings and research studies.

Asymptomatic transmission is no longer in doubt, according to Dr Massimo Sartelli [Image: Freepik].

While studies have confirmed the presence of asymptomatic disease transmission as an aspect of SARS-CoV-2‘s disease profile, the unanswered question is to what extent asymptomatic transmission is driving infection rates. On this point, the scientific community has delivered confusing and occasionally conflicting information.

An asymptomatic carrier is defined as someone who has been infected, but does not display symptoms as yet. Japanese and South Korean studies have found that asymptomatic carriers can (but not always do) display the characteristic ground-glass opacities typical of SARS-CoV-2 when subjected to a CT scan.

Moreover, persons who are currently categorised as having asymptomatic COVID-19 infections appear on a spectrum ranging from those who are truly asymptomatic to those who have mild symptoms but don’t seek medical support.  The latter group is sometimes referred to as “pauci-symptomatic” or “subclinical” because they are below the threshold of detection by the healthcare system.

INFECTION RATE

In a study published on June 3 in the Annals of Internal Medicine, researchers at the Scripps Research Translational Institute reviewed data from 16 different groups of COVID-19 patients from around the world to get a better idea of how many cases of coronavirus can likely be traced to persons who spread the virus without ever knowing they were infected. They found that the asymptomatic infection rate could be as high as 40% to 45%.

Whether asymptomatic COVID-19 carriers are less contagious remains unclear and more research is required. Based on current evidence, it seems that asymptomatically infected people can transmit COVID-19, however they may be less likely to transmit the virus than those who develop symptoms.

SOURCE: Global Alliance for Infections in Surgery