SARS-CoV-2 transmission without symptoms | Science

SARS-CoV-2 transmission without symptoms | Science: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a potentially long incubation period and spreads opportunistically among those who are unaware they are infected. Asymptomatic COVID-19 cases are those that do not develop symptoms for the duration of infection, whereas presymptomatic cases develop symptoms later in the course of infection, but both are crucial drivers of transmission ([ 1 ][1]). Transmission without symptoms poses specific challenges for determining the infectious timeline and potential exposures. Early in the pandemic, most transmission was from undocumented cases, suggesting that spread was driven by people who were either asymptomatic or experiencing such mild disease that it was not recognized as COVID-19 ([ 2 ][2]). Contagious people without observable signs of illness make infection prevention efforts vulnerable to compliance with masking, distancing, hand hygiene, symptom screening, and ultimately, people staying home when possible. The lack of widespread testing in asymptomatic individuals further complicates COVID-19 mitigation and control efforts. The true occurrence and transmission capacity of asymptomatic and presymptomatic infections a