An editorial in the British Medical Journal cited a study of almost 10 million people in Wuhan, China that found “no evidence of asymptomatic transmission.”
“The transmission rates to contacts within a specific group (secondary attack rate) may be 3-25 times lower for people who are asymptomatic than for those with symptoms,” the study said. “A city-wide prevalence study of almost 10 million people in Wuhan found no evidence of asymptomatic transmission.”
“A mass screening program of more than 10 million residents of Wuhan, China, performed after SARS-CoV-2 was brought under control, has identified 300 asymptomatic cases of COVID-19, none of which was infectious,” BMJ also reports.
Speaking at a June 8th, 2020 briefing in Geneva, World Health Organization’s Emerging Diseases and Zoonosis Unit Director Maria Van Kerkhove called asymptomatic COVID-19 transmission “very rare”: