Here are some more extracts from the links provided by grey_whiskers. This is what I see: (each link in order from the first, followed by the key conclusions copied from the article and my translation of what that really means).
https://pubmed.ncbi.nlm.nih.gov/31159777/
Contamination by respiratory viruses on outer surface of medical masks used by hospital healthcare workers
Conclusion: Respiratory pathogens on the outer surface of the used medical masks may result in self-contamination. The risk is higher with longer duration of mask use (> 6 h) and with higher rates of clinical contact. Protocols on duration of mask use should specify a maximum time of continuous use, and should consider guidance in high contact settings. Viruses were isolated from the upper sections of around 10% samples, but other sections of masks may also be contaminated. HCWs should be aware of these risks in order to protect themselves and people around them.
Translation: Even though the mask does not catch all the virus particles, it does catch some, and then is unsafe to handle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/
A cluster randomised trial of cloth masks compared with medical masks in healthcare workers
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.
Translation: Cloth masks are even more usless than surgical masks
https://www.medrxiv.org/content/10.1101/2020.04.01.20049528v1
Facemasks and similar barriers to prevent respiratory illness such as COVID-19: A rapid systematic review
Discussion Based on the RCTs we would conclude that wearing facemasks can be very slightly protective against primary infection from casual community contact, and modestly protective against household infections when both infected and uninfected members wear facemasks. However, the RCTs often suffered from poor compliance and controls using facemasks.
Translation: Seems a little like "getting slightly pregnant" Never mind how inconvenient it is...
https://www.medrxiv.org/content/10.1101/2020.03.30.20047217v2
Physical interventions to interrupt or reduce the spread of respiratory viruses. Part 1 - Face masks, eye protection and person distancing: systematic review and meta-analysis
RESULTS We included 15 randomised trials investigating the effect of masks (14 trials) in healthcare workers and the general population and of quarantine (1 trial). We found no trials testing eye protection. Compared to no masks there was no reduction of influenza-like illness (ILI) cases (Risk Ratio 0.93, 95%CI 0.83 to 1.05) or influenza (Risk Ratio 0.84, 95%CI 0.61-1.17) for masks in the general population, nor in healthcare workers (Risk Ratio 0.37, 95%CI 0.05 to 2.50). There was no difference between surgical masks and N95 respirators: for ILI (Risk Ratio 0.83, 95%CI 0.63 to 1.08), for influenza (Risk Ratio 1.02, 95%CI 0.73 to 1.43). Harms were poorly reported and limited to discomfort with lower compliance. The only trial testing quarantining workers with household ILI contacts found a reduction in ILI cases, but increased risk of quarantined workers contracting influenza. All trials were conducted during seasonal ILI activity.
Translation: No masks (neither surgical nor N95) worked to prevent infection. Quarantine worked somewhat, but with other risks for quarantined workers
https://www.nejm.org/doi/full/10.1056/NEJMp2006372
The site was under maintenance probably can try later
Translation:
https://jamanetwork.com/journals/jama/fullarticle/2749214
N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel
Findings In this pragmatic, cluster randomized clinical trial involving 2862 health care personnel, there was no significant difference in the incidence of laboratory-confirmed influenza among health care personnel with the use of N95 respirators (8.2%) vs medical masks (7.2%).
Translation: Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.
https://www.cmaj.ca/content/188/8/567
Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis
Conclusion
Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.
Translation: This was a very extensive and detailed study in 2016 that concluded no signiicasant difference in respiratory infections with either mask
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5779801/
The use of masks and respirators to prevent transmission of influenza: a systematic review of the scientific evidence
In conclusion, there is a limited evidence base to support the use of masks and/or respirators in healthcare or community settings. Mask use is best undertaken as part of a package of personal protection, especially including hand hygiene in both home and healthcare settings. Early initiation and correct and consistent wearing of masks/respirators may improve their effectiveness. However, this remains a major challenge – both in the context of a formal study and in everyday practice.
Translation: This wasn't a "study", it was a long review of many other studies in many different environments. effectively says "we don't really know" (hint - probably looking for more funding in 2011)
https://pubmed.ncbi.nlm.nih.gov/19216002/
Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: a randomized controlled trial
Conclusion: Face mask use in health care workers has not been demonstrated to provide benefit in terms of cold symptoms or getting colds. A larger study is needed to definitively establish noninferiority of no mask use.
Translation: Masks don't significantly inhibit transmission of virus
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/
A cluster randomised trial of cloth masks compared with medical masks in healthcare workers
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.
Translation: Cloth masks are actually WORSE than no mask
That's enough for tonite - I'll try to finish up tomorrow