1. Wearing Face Masks
One study found that facemasks were 79% effective in preventing transmission, if they were used by all household members prior to symptoms occurring . Another study found that disease transmission was 7.5 times higher in countries that did not have a mask mandate or universal mask use . A third study confirmed this result .
* Considerations for Wearing Cloth Face Coverings – CDC
* How to Make Cloth Face Coverings – CDC
* Coronavirus Face Masks: What You Should Know – WebMD
* What Is the Best Type of Face Mask for You? – Healthline
* Study  — No difference in protection from influenza between N95 masks and Surgical masks.
* Study  – Comparing different fabrics for making face masks.
2. Practice Social Distancing
Study  — concluded the following: “Adoption of government-imposed social distancing measures reduced the daily growth rate by 5.4 percentage points after 1–5 days, 6.8 after 6–10 days, 8.2 after 11–15 days, and 9.1 after 16–20 days.” 
Social distancing works. And the longer that a community practices social distancing, the stronger the effects. Within 3 weeks, the reduction in the daily growth of the case rate (the rate at which people are infected with Covid-19) is 9.1%.
The same study  — found that Shelter In Place Orders (SIPO) and closures of restaurants/bars/entertainment-related businesses had the largest benefits. Banning large events had a smaller benefit. Closure of schools did not substantially slow the spread of Covid-19, but the confidence interval cannot rule this out .
Shelter in place orders have a large effect because it affects a large number of persons, especially the elderly, who are at greatest risk. Closures of businesses with crowded indoor venues also had a large benefit. The banning of individual large events unsurprisingly had a smaller effect because these are one-time gatherings with a corresponding one-time risk. By comparison, crowded indoor businesses operate on a daily basis, accumulating a greater risk over time.
Schools present the least risk because children are at a much lower risk than adults. However, the confidence interval in this study could not exclude the possibility that closing schools had a substantial benefit. So we cannot be sure of the risk level posed by reopening schools in the fall of 2020.
4. Wash Hands Frequently [5, 6]
In a study of respiratory illnesses in general, handwashing reduced the incidence of respiratory illnesses by 18% . It has long been known that handwashing is an easy effective means to prevent the spread of disease, especially for diseases that can be contracted by the fecal-oral route (of which Covid-19 is one). This study considered respiratory illnesses in general, but Covid-19 can be contracted by either the respiratory or the gastrointestinal route.
Another study examined nationwide tendencies to wash hands or not, after using the bathroom — termed “handwashing culture” . The study found a strong correlation between hand washing and the infection rate of Covid-19 nationwide: “handwashing culture alone predicts approximately 22% of international variation in COVID-19 outbreak magnitude” .
This study was Covid-19 specific. A large percentage of the infection rate of Covid-19 was attributed to whether persons in a society are accustomed to washing their hands after using the bathroom. Those without this healthy custom have a greater risk of Covid-19. The international variation in the extent of Covid-19 was attributable (at about 22%) to this difference in custom.
The recommended practices of wearing a face mask, practicing social distancing, washing one’s hands frequently (especially after using the bathroom), and restricting or shutting down crowded venues are all effective means to slow the spread of Covid-19, during a deadly pandemic.
Ronald L. Conte Jr.
Note: the author of this article is not a doctor, nurse, or healthcare provider.
1. Wang, Y., et al., “Reduction of secondary transmission of sars-cov-2 in households by face mask use, disinfection and social distancing: a cohort study in Beijing, China.” BMJ Glob. Heal. 5, e002794 (2020).
2. Leffler, CT, et al., “Association of country-wide coronavirus mortality with demographics, testing, lockdowns, and public wearing of masks.” update July 2, 2020. medRxiv (2020).
3. Kenyon, C. “Widespread use of face masks in public may slow the spread of SARS CoV-2: an ecological study.” medRxiv, 2020.03.31.20048652 (2020).
4. Courtemanche, Charles, et al. “Strong Social Distancing Measures In The United States Reduced The COVID-19 Growth Rate: Study evaluates the impact of social distancing measures on the growth rate of confirmed COVID-19 cases across the United States.” Health Affairs (2020): 10-1377.
See also “Appendix Exhibit 4” in Supplemental File.
5. Najnin, Nusrat, et al. “Impact of a large-scale handwashing intervention on reported respiratory illness: Findings from a cluster-randomized controlled trial.” The American journal of tropical medicine and hygiene 100.3 (2019): 742-749.
6. Pogrebna, Ganna, and Alexander Kharlamov. “The Impact of Cross-Cultural Differences in Handwashing Patterns on the COVID-19 Outbreak Magnitude.” (2020).
7. Radonovich, Lewis J., et al. “N95 respirators vs medical masks for preventing influenza among health care personnel: a randomized clinical trial.” Jama 322.9 (2019): 824-833.
8. Konda, Abhiteja, et al. “Aerosol filtration efficiency of common fabrics used in respiratory cloth masks.” ACS nano 14.5 (2020): 6339-6347.