軽症状・無症状、無自覚感染者が感染源

サイエンス誌に掲載されたこちらの論文では、中国データに基づいて、確認される感染者１人につき、５〜10人の無症候性感染者がいるとしてる。そして、これらの症状が軽い、あるいは無症候の感染者が新規感染の80%の感染元となってるとのことだ。https://t.co/LDHLV6IiKq

— Dr. RawheaD@🏠 (@RawheaD) March 19, 2020

INFECTIOUS DISEASE Mar. 16 2020
'Stealth Transmission' Fuels Fast Spread of Coronavirus Outbreak

Scientists find that up to 86 percent of coronavirus infections go undetected
BY ALAN BOYLE on March 16, 2020 at 11:00 am


Those undocumented infections were about half as contagious as the documented cases, but were the source of two-thirds of the documented cases, according to a study published online today by the journal Science.

The findings parallel other research into the role of what’s known as stealth or cryptic transmission in spreading the potentially deadly virus. They also underscore the importance of widespread testing, even if patients aren’t experiencing serious symptoms, particularly during the early phases of transmission.


When the researchers started putting their data together, they suspected the model would show that reported cases were just “the tip of the iceberg” for the spread of infection, Shaman said. That suspicion was based on past research involving more benign coronaviruses — such as those that cause the common cold. Such research suggested that most infections caused symptoms so mild that the people who had the virus didn’t bother to report them.

Public health officials have found that the effect of COVID-19 infections varies widely, depending on the presence of underlying medical conditions such as respiratory or heart problems, as well as demographic factors such as age. Patients over 60 may be hit particularly hard, while patients under 30 are more likely to experience mild symptoms.

Another factor may be how transmissible the virus is before the onset of symptoms, but it’s too early to get definitive metrics on that factor, Shaman said. It’s also too early to say definitively whether people who have been through COVID-19 build up lifelong immunity. That’s not typically the case with colds.

　軽症状、無症状、無自覚感染者が感染源の大半。

　感染者に接触した人たちに症状がでていなくても検査するという日本の制度は、悪くはないわなあ。

　ただ、医者に相談したり申告するほど大した症状がでない人たちが多いとなるど感染拡大を防ぎようもないーーー若い人たちにおおいわけだねえ。

　しかも、感染して生き残ったらこれに対して生涯通用するような免疫ができるものなのか、どうかもまだわからないんだね。