Reference:

Poletti, Piero, Marcello Tirani, Danilo Cereda, Filippo Trentini, Giorgio Guzzetta, Giuliana Sabatino, Valentina Marziano, et al. “Probability of Symptoms and Critical Disease after SARS-CoV-2 Infection.” ArXiv:2006.08471 [q-Bio], June 22, 2020. http://arxiv.org/abs/2006.08471.

Experimental Design:

As COVID-19 erupted in Lombardy, Italy between February and April, the researchers identified 3,420 coronavirus patients and their 5,484 close contacts. They tested all of the close contacts for the coronavirus, and tracked their symptoms.

Results:

Of the 5,484 people who were in close contact with coronavirus patients:

• 2,824 (around 51.5% of close contacts) also tested positive.
• Out of the 2,824 people who tested positive, 61% showed NO SYMPTOMS.
• Older patients were more likely to show symptoms:
  • Among those younger than 20, 81.9% had no symptoms
  • Among those older than 80, 35.4% had no symptoms

What does this mean?

You’ve probably seen a lot of different numbers on asymptomatic infection. Depending on when these studies were conducted or how many people were studied, they tend to report different numbers.

But, whether the true asymptomatic rate is 61% or not, all of the studies can agree on one thing: anyone can get infected with the coronavirus, infect friends and family, and show NO SYMPTOMS. As a result, we all have to take precautions by wearing masks and practicing social distancing.

Up Next: How are masks effective?

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