Studies and Reviews:
A study on infectivity of asymptomatic SARS-CoV-2 carriers - Respiratory Medicine - "Based on the foregoing discussion, we conclude that the infectivity of some asymptomatic SARS-CoV-2 carriers might be weak. This finding implicates that there is not needful (sic) to worry unduly for asymptomatic or mild patients during the ongoing COVID-19 pandemic. Furthermore, excessive virus nucleic acid detection is unnecessary, which can relieve the pressure on public health resources."
Post-lockdown SARS-CoV-2 nucleic acid screening in nearly ten million residents of Wuhan, China - Nature - "Compared with symptomatic patients, asymptomatic infected persons generally have low quantity of viral loads and a short duration of viral shedding, which decrease the transmission risk of SARS-CoV-2. In the present study, virus culture was carried out on samples from asymptomatic positive cases, and found no viable SARS-CoV-2 virus. All close contacts of the asymptomatic positive cases tested negative, indicating that the asymptomatic positive cases detected in this study were unlikely to be infectious."
Contact Settings and Risk for Transmission in 3410 Close Contacts of Patients With COVID-19 in Guangzhou, China - Annals of Internal Medicine - "Our results showed that patients with COVID-19 who had more severe symptoms had a higher transmission capacity, whereas transmission capacity from asymptomatic cases was limited. This supports the view of the World Health Organization that asymptomatic cases were not the major drivers of the overall epidemic dynamics."
Household Transmission of SARS-CoV-2, A Systematic Review and Meta-analysis - Journal of the American Medical Association - "Estimated mean household secondary attack rate from symptomatic index cases (18.0%) was significantly higher than from asymptomatic or presymptomatic index cases (0.7%)"
Asymptomatic transmission of covid-19 - BMJ - "Searching for people who are asymptomatic yet infectious is like searching for needles that appear and reappear transiently in haystacks, particularly when rates are falling."
"The absence of strong evidence that asymptomatic people are a driver of transmission is another good reason for pausing the roll out of mass testing in schools, universities, and communities."