A new study from Wuhan shows that asymptomatic transmission is not important in SARS-CoV-2.
A strict lockdown regime was implemented in Wuhan between January 23 and April 8, 2020. After the lockdown ended, a citywide SARS-CoV-2 nucleic acid screening program was conducted between May 14 and June 1, 2020. All city residents aged six years or older were invited to participate and 9,899,828 (92.9%) took part. The result: No new symptomatic cases were identified and only 300 asymptomatic cases were identified. The 1,174 close contacts of asymptomatic cases all tested negative.
In summary, the researchers concluded that the detection rate of asymptomatic positive cases in the Wuhan after lockdown was very low (0.303/10,000) and there is no evidence that the identified asymptomatic positive cases were infectious at all.
