I’m thrilled to begin my Blog with you. I’m going to begin by asking, “Masks: to wear or not to wear?” That is the question! As you know it’s been a local and global debate. Let’s do a deep dive into some personal protective measures which are being suggested to control the COVID-19 Pandemic.
There apparently was a scramble by WHO and the CDC here in the US, to develop a plan in 2020. Researchers from BMJ, Yale, and Cold Spring Harbor Laboratory updated a Cochrane review that included a meta-analysis of observational studies during the SARS outbreak of 2003 with other resources from October 2010 up to April 2020, later written up in medRxiv.
Elsevier accepted a research article from Sri Lanka researchers regarding the “Transmission of COVID-19 virus by droplets and aerosols: A critical review on the unresolved dichotomy” on June 10, 2020. The Elsevier COVID-19 resource center was created with free information in English and Mandarin and makes its research available in PubMed Central and other publicly funded repositories, such as the WHO COVID databases.
Finally, a study was conducted in preparation of guidelines by the WHO on the use of nonpharmaceutical interventions for pandemic influenza in nonmedical settings by a team in the School of Public Health, University of Hong Kong, Hong Kong, China. That study, and others, done by the same team can be found on the CDC website.
I’ll refer to all three of those resources in this Blog, plus information from the CDC website.
In quoting from the BMJ report, the 6 authors independently assessed the risk of bias using the Cochrane tool and extracted data and reported results with risk ratios and 95% Confidence Intervals from 15 randomized trials investigating the effect of masks in healthcare workers and the general population, with one trial of quarantine. There were none on eye protection. Compared to no masks there was no reduction of influenza-like illness (ILI) cases or influenza for masks in the general population, nor healthcare workers. There was no difference between surgical masks and N95 respirators for ILI or influenza. The only trial testing quarantining workers with household ILI contacts found a reduction in ILI cases, but increased risk of quarantined workers contracting influenza. These authors recommended the use of masks with other measures.
I believe the abstract from the Hong Kong team says it best in the abstract for their report: Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings- Personal Protective and Environmental Measures:
There were 3 influenza pandemics in the 20th century, and there has been 1 so far in the 21st century. Local, national, and international health authorities regularly update their plans for mitigating the next influenza pandemic in light of the latest available evidence on the effectiveness of various control measures in reducing transmission. Here, we review the evidence base on the effectiveness of nonpharmaceutical personal protective measures and environmental hygiene measures in nonhealthcare settings and discuss their potential inclusion in pandemic plans. Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on the transmission of laboratory-confirmed influenza. We similarly found limited evidence on the effectiveness of improved hygiene and environmental cleaning. We identified several major knowledge gaps requiring further research, most fundamentally an improved characterization of the modes of person-to-person transmission.
So, at present, there is no evidence from these studies on the effectiveness of universal masking for healthy people in the community from being infected by respiratory viruses, including COVID-19. Disposable medical masks (surgical masks) were designed for single use to protect against accidental contamination of a patient’s wound, to protect the wearer against splashes or the sprays of bodily fluids, and to protect an immune-compromised patient from potential introduction of infection. After contact with any of those patients, the mask is discarded, followed by 20-seconds of handwashing and likewise, a new mask being used for the next patient situation, preceded by a 20-second handwash (named “hand hygiene” in the last resource and as directed by CDC guidelines). The Hong Kong team recognized problems arise when lacking the availability of disposable surgical masks, improper use of the mask, non-effective “respiratory etiquette” (without masks), and length of time the mask is worn.
Hand hygiene with proper use of masks is encouraged not only by the CDC but also supported by my research. According to the CDC, hand sanitizers are not a substitute for handwashing. In fact, sanitizers only remove certain germs, while hand washing with regular soap and running water literally wash away more germs as well as toxic chemicals. The caveat of hand sanitizers is that they are only effective short-term until you touch something, and handwashing is effective only if done adequately after the 11 or so situations when your parent or guardian may have said, “Wash your hands.” CDC is very specific that proper handwashing is: wet hands with clean running water and apply soap, create a lather, scrub all surfaces of your hands for 20 seconds, rinse your hands with running water, and dry with a clean towel.
When it comes to surface cleaning, the Hong Kong report found no evidence that surface and object cleaning could reduce influenza transmission. However, it does have an impact on the prevention of other infectious diseases. On April 5, 2021, the CDC stated that surface transmission of SARS-Cov-2 is considered low compared to direct contact, droplet transmission, or airborne transmission. Their case reports indicated that the virus is transmitted between people touching surfaces an ill person has recently coughed or sneezed upon, and then directly touching the mouth, nose, or eyes. Hand hygiene is a barrier to surface (“fomite”) transmission and has been associated with a lower risk of infection. Studies indicate that there is a 99% reduction of SARS-Cov-2 and other coronaviruses under normal indoor environment conditions within 3 days on common non-porous surfaces like stainless steel, plastic, and glass.
That leads me to the size of respiratory virus particles. Generally, we know that infected people spread viral particles when they talk, breathe, cough, or sneeze. Those particles are encapsulated in globs of mucus, saliva, and water, and their fate is related to their size and aerodynamic capabilities. Large globs fall faster and are slower to evaporate than smaller globs which will linger in the air. The WHO and CDC postulate that the particles of more than 5 mcg are droplets; less than 5 mcg are aerosols, which linger in the air for a longer time. Small aerosols are more susceptible to be inhaled deep into the lung, which can cause infections in the lower respiratory tissues. Large droplets are trapped in the upper airways.
In closing, it seems that the use of any of these nonpharmaceutical interventions depends upon the situation at hand and an individual’s knowledge-based level of caution, particularly to their individual immunity and circumstances. The field of medicine is never precise because of those variabilities. Apparently from this research, the current Pandemic will not end with mask mandates. What are your thoughts on this?
My next Blog will be on mRNA vaccines.