[BostonCard]

Study 1:  ...However, compliance with mask use was less than 50%. In an adjusted analysis of compliant subjects, masks as a group had protective efficacy in excess of 80% against clinical influenza-like illness. The efficacy against proven viral infection and between P2 masks (57%) and surgical masks (33%) was non-significant. ... In compliant users, masks were highly efficacious.



Study 2:  This study paired hand hygiene with wearing masks versus neither, so it doesn't really indicate anything about face masks themselves.



Study 3: Subjects in residence halls at a university [quote]Participants were assigned to face mask and hand hygiene, face mask only, or control group during the study. Discrete-time survival models using generalized estimating equations to estimate intervention effects on ILI and confirmed influenza A/B infection over a 6-week study period were examined. A significant reduction in the rate of ILI was observed in weeks 3 through 6 of the study, with a maximum reduction of 75% during the final study week (rate ratio [RR] = 0.25, [95% CI, 0.07 to 0.87]). Both intervention groups compared to the control showed cumulative reductions in rates of influenza over the study period, although results did not reach statistical significance.

I think the studies support the general consensus on this which is that masks can help when a) the masks are properly fitted, b) the users are compliant with them, c) the users use them properly d) it is paired with other hygiene methods (hand washing, gloves, etc).

Note, the type of mask required is dependent on how the virus/bacteria is transmitted.  If it is mostly in the upper respiratory tract, the particles produced are mostly droplets, and droplet precautions (surgical mask plus gloves, possibly with an eye shield) are adequate.  If the source of the virus/bacteria is in the lungs and it is spread via coughing, then full respiratory/airborne precautions are required (N95 mask), ideally a negative pressure room.

Wikipedia has a nice summary of what each type of infection requires and what each type entails.

Here's what they say for SARS (also a coronavirus that causes a respiratory syndrome:

Infection or condition	Infection or condition	Precautions duration²	Precautions comments
Severe acute respiratory syndrome (SARS)	Airborne / Contact / Droplet	DI plus 10 days after resolution offever, provided respiratory symptoms are absent or improving	Airborne Precautions preferred; D if AIIR unavailable. N95 or higher respiratory protection; surgical mask if N95 unavailable; eye protection (goggles, face shield); aerosol-generating procedures and "supershedders" highest risk for transmission via small droplet nuclei and large droplets.[65][66][67] Vigilant environmental disinfection (see www.cdc.gov/ncidod/sars)

Bottom line, I don't think a mask in and of itself (especially if it is not a fit, N95 mask) will protect anyone very well.

BC

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California now has its first coronavirus death.

https://apple.news/A_WhbKs2IStGlwuMjP14H_A

The scary thing is this quote:

The individual’s likely exposure occurred during international travel on a Princess cruise ship that departed Feb. 10 from San Francisco to Mexico and returned Feb. 21.

If the individual was exposed on the cruise, the experience with the Diamond Princess cruise in Japan, where there was widespread exposure to the virus suggests that a lot of people could potential be positive.  Moreover, with a cruise departing from SF, there will be a lot of Bay Area residents exposed.

BC

[BostonCard]

Study 1:  ...However, compliance with mask use was less than 50%. In an adjusted analysis of compliant subjects, masks as a group had protective efficacy in excess of 80% against clinical influenza-like illness. The efficacy against proven viral infection and between P2 masks (57%) and surgical masks (33%) was non-significant. ... In compliant users, masks were highly efficacious.



Study 2:  This study paired hand hygiene with wearing masks versus neither, so it doesn't really indicate anything about face masks themselves.



Study 3: Subjects in residence halls at a university [quote]Participants were assigned to face mask and hand hygiene, face mask only, or control group during the study. Discrete-time survival models using generalized estimating equations to estimate intervention effects on ILI and confirmed influenza A/B infection over a 6-week study period were examined. A significant reduction in the rate of ILI was observed in weeks 3 through 6 of the study, with a maximum reduction of 75% during the final study week (rate ratio [RR] = 0.25, [95% CI, 0.07 to 0.87]). Both intervention groups compared to the control showed cumulative reductions in rates of influenza over the study period, although results did not reach statistical significance.

I think the studies support the general consensus on this which is that masks can help when a) the masks are properly fitted, b) the users are compliant with them, c) the users use them properly d) it is paired with other hygiene methods (hand washing, gloves, etc).

Note, the type of mask required is dependent on how the virus/bacteria is transmitted.  If it is mostly in the upper respiratory tract, the particles produced are mostly droplets, and droplet precautions (surgical mask plus gloves, possibly with an eye shield) are adequate.  If the source of the virus/bacteria is in the lungs and it is spread via coughing, then full respiratory/airborne precautions are required (N95 mask), ideally a negative pressure room.

Wikipedia has a nice summary of what each type of infection requires and what each type entails.

Here's what they say for SARS (also a coronavirus that causes a respiratory syndrome:

Infection or condition	Infection or condition	Precautions duration²	Precautions comments
Severe acute respiratory syndrome (SARS)	Airborne / Contact / Droplet	DI plus 10 days after resolution offever, provided respiratory symptoms are absent or improving	Airborne Precautions preferred; D if AIIR unavailable. N95 or higher respiratory protection; surgical mask if N95 unavailable; eye protection (goggles, face shield); aerosol-generating procedures and "supershedders" highest risk for transmission via small droplet nuclei and large droplets.[65][66][67] Vigilant environmental disinfection (see www.cdc.gov/ncidod/sars)

Bottom line, I don't think a mask in and of itself (especially if it is not a fit, N95 mask) will protect anyone very well.

BC

---

California now has its first coronavirus death.

https://apple.news/A_WhbKs2IStGlwuMjP14H_A

The scary thing is this quote:

The individual’s likely exposure occurred during international travel on a Princess cruise ship that departed Feb. 10 from San Francisco to Mexico and returned Feb. 21.

If the individual was exposed on the cruise, the experience with the Diamond Princess cruise in Japan, where there was widespread exposure to the virus suggests that a lot of people could potential be positive.  Moreover, with a cruise departing from SF, there will be a lot of Bay Area residents exposed.

BC