布マスクは感染源になるかも、と。

buveryさんがリツイート

「子供のマスクは手作りを」　学校再開に向け文科省が呼びかけ＞これはやっちゃダメ。布マスクはむしろウイルス感染を増やすという論文（MacIntyre et al. 2015. BMJ Open 5:e006577）が出てます。病院では布マスクを使っていない。文部科学省に届くように拡散してください。https://t.co/Z7CWgGQTQ1

— Tetsukazu Yahara (@TetYahara) March 25, 2020

Objective: The aim of this study was to compare the
efficacy of cloth masks to medical masks in hospital
healthcare workers (HCWs). The null hypothesis is that
there is no difference between medical masks and
cloth masks.

Results: The rates of all infection outcomes were
highest in the cloth mask arm, with the rate of ILI
statistically significantly higher in the cloth mask arm
(relative risk (RR)=13.00, 95% CI 1.69 to 100.07)
compared with the medical mask arm. Cloth masks
also had significantly higher rates of ILI compared with
the control arm. An analysis by mask use showed ILI
(RR=6.64, 95% CI 1.45 to 28.65) and laboratory　confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were
significantly higher in the cloth masks group compared
with the medical masks group. Penetration of cloth
masks by particles was almost 97% and medical
masks 44%.
Conclusions: This study is the first RCT of cloth
masks, and the results caution against the use of cloth
masks. This is an important finding to inform
occupational health and safety. Moisture retention,
reuse of cloth masks and poor filtration may result in
increased risk of infection. Further research is needed
to inform the widespread use of cloth masks globally.
However, as a precautionary measure, cloth masks
should not be recommended for HCWs, particularly in
high-risk situations, and guidelines need to be
updated

. It is also unknown whether the rates of infection
observed in the cloth mask arm are the same or higher
than in HCWs who do not wear a mask, as almost all
participants in the control arm used a mask. The physical properties of a cloth mask, reuse, the frequency and
effectiveness of cleaning, and increased moisture retention, may potentially increase the infection risk for
HCWs. The virus may survive on the surface of the facemasks,29 and modelling studies have quantified the contamination levels of masks.30 Self-contamination through
repeated use and improper doffing is possible. For
example, a contaminated cloth mask may transfer pathogen from the mask to the bare hands of the wearer. We
also showed that filtration was extremely poor (almost
0%) for the cloth masks. Observations during SARS suggested double-masking and other practices increased the
risk of infection because of moisture, liquid diffusion
and pathogen retention.31 These effects may be associated with cloth masks.

病院環境で、布マスクは医療用マスクと比べて有意義に感染率がたかい、と。

しないよりいいだろう、と思ったら・・・しないで医療関係従事しないから、わからんけど、病原菌がついた布マスクに触れて手からか感染したり、マスクに湿気あるから、感染の危険をたかめるのではないか、と。





これはどうなるんだろうね。


少なくとも、医療、介護関係者にはしっかりしたものを国が提供すべきだろうね。