COVID-19 transmission from asymptomatic individuals

Editor's Note

This decision analytical model from researchers at the Centers for Disease Control and Prevention finds that transmission of COVID-19 by asymptomatic individuals accounts for more than half of all transmissions.

Combining baseline assumptions that peak infectiousness occurs at the median of symptom onset and that 30% never develop symptoms and are 75% as infectious as those who develop symptoms, the researchers found that:

• 59% of all transmissions come from asymptomatic transmissions
• 35% of transmissions come from presymptomatic individuals
• 24% of transmissions come from those who never develop symptoms.

The findings suggest that measures such as hand hygiene, social  distancing, wearing masks, and strategic testing of individuals who are not ill will be key to slowing the spread of COVID-19 until vaccines are available and widely used, the researchers say.