Close conversations with mask-wearing infected people pose infection risk

The Yomiuri Shimbun

15:39 JST, February 3, 2022

Keeping one’s distance remains an important factor in preventing infection with the novel coronavirus, researchers in Japan announced Wednesday.

The risk of infection with the omicron variant increases when an infected person, even wearing a mask, talks with another person within 50 centimeters, the researchers said.

The team of researchers, including members of the Riken research institute and Kobe University, made calculations using the Fugaku supercomputer.

Based on the findings, the team also highlighted the importance of reducing the time people are in contact with others.

The calculations postulate that omicron is 50% more contagious than the delta variant. Using Riken’s supercomputer, the researchers tried to determine how much of the virus enters the body under different conditions, such as whether the infected person wears a mask, how long the person talks with others and how far the people are from each other.

Fugaku’s calculations show that there is almost zero chance of infection if a person is at least 1 meter away while talking with a mask-wearing infected person for 15 minutes indoors. However, the risk increases to about 10% if they are talking for one hour and are only 50 centimeters apart.

Mask-wearing remains important, as the chance of infection rises to about 60% even if a person is 1 meter away from an infected person who speaks while not wearing a mask for 15 minutes. If the distance is reduced to 50 centimeters or less, the person is nearly certain to contract the virus.