Meta-analysis finds high global percentage of asymptomatic COVID-19 infections

Editor's Note

This study by Chinese researchers finds a high percentage of asymptomatic COVID-19 infections worldwide, which highlights the potential transmission risk of asymptomatic infections in communities.

In this review and meta-analysis of 95 studies, which include nearly 30 million individuals undergoing testing, the percentage of asymptomatic infections was 0.25% in the tested population and 40.5% in those with confirmed COVID-19.

Asymptomatic infections in the tested population were higher in:

• nursing home residents or staff (4.52%)
• pregnant women (2.34%)
• air or cruise travelers (2.02%)
• close contacts (1.46%)
• healthcare workers or in-hospital patients (0.75%)
• community residents (0.40%).

Asymptomatic infections in those with confirmed COVID-19 were higher in:

• pregnant women (54.11%)
• air or cruise travelers (52.91%)
• nursing home residents or staff (47.53%).
• community residents (39.74%)
• healthcare workers or in-hospital patients (30.01%)
• close contacts (26.94%).

The researchers conclude that the high percentage of asymptomatic infections underscores the need for required screening of asymptomatic individuals, and asymptomatic infections should be managed similar to those with confirmed infections, including isolating and contact tracing.