Asymptomatic SARS-CoV-2 Infections Among Persons Entering China From April 16 to October 12, 2020 | Global Health | JAMA | JAMA Network
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Research Letter
February 2, 2021

Asymptomatic SARS-CoV-2 Infections Among Persons Entering China From April 16 to October 12, 2020

Author Affiliations
  • 1Chinese Center for Disease Control and Prevention, Beijing, China
JAMA. 2021;325(5):489-492. doi:10.1001/jama.2020.23942

The magnitude of asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a question of global concern. Individuals who test positive for SARS-CoV-2 infection via a polymerase chain reaction (PCR) test but lack coronavirus disease 2019 (COVID-19)–like symptoms must be followed up through the incubation period to distinguish individuals with asymptomatic infection from those with presymptomatic infection.1

China successfully controlled its initial COVID-19 epidemic in March 20202 and has since focused on preventing importation of SARS-CoV-2 infection. Beginning April 1, 2020, persons entering China via air, sea, or land have been mandatorily tested for SARS-CoV-2 infection by PCR test at border checkpoints. Individuals who have tested positive have been hospitalized in isolation and those who have tested negative have been quarantined for 14 days at centralized facilities and then retested on day 13. We assessed the proportion of international entrants to China with asymptomatic SARS-CoV-2 infection.