Thread by @DearPandemic

1/ Q: Have we learned anything new recently about #COVID19 transmission?

A: Recent analysis of infection clusters in Japan bolsters evidence that heavy breathing in close proximity is high risk activity for community spread.

2/ Japan has been tracing “clusters” of coronavirus infections: 5 or more confirmed cases with primary exposure reported at a common event or venue.
The recently summary published by the @CDCgov: wwwnc.cdc.gov/eid/article/26…
is full of interesting findings:

3/
🏥 Health care facilities + nursing homes are a large source of infection clusters, accounting for 46% of the clusters examined.

🎤 Many clusters were associated with heavy breathing in close proximity: think karaoke, conversations at clubs and bars, and exercising in gyms.

4/
🎫The largest non-healthcare cluster was among more than 30 people who attended a live music concert, including performers, audience members, and event staff.

🤒 The most common age group for probable primary cases were 20-39 year olds.

5/
😶 Where date of transmission could be determined, 41% of the primary cases were presymptomatic or asymptomatic at the time. Only 1 had a cough at the time of transmission.

This is why masking is important: people may not know they are sick or at risk of spreading #COVID.

6/ Some caveats: In this report, only 61% of cases of local transmission had links to known cases and thus could be traced in this way. This means 39% of cases came from unknown sources, so activities not mentioned here can still carry #Risk.

7/ Overall this new evidence supports Japan’s push for the population to avoid the “Three Cs”:
Closed spaces with poor ventilation,
Crowded places, and
Close-contact settings.

Sadly, it will take time to safely return to events with lots of cheering and singing...

8/ So MASK UP friends, and save the Karaoke for home for now!