The COVID-19 Pandemic & More: Time to assess lessons learned, and to implement science-based measures to reduce airborne transmission – Colorado School of Public Health

Colorado’s COVID-19 epidemic curve may be starting to bend. Last week’s hospitalization count had dipped below 400 to 399, down from 440 the prior week. Case numbers are ebbing downward, and test positivity has plateaued. The level of vaccination raises concern about population immunity, particularly if the next variant is more transmissible than prior variants (a likely possibility) and more virulent (an uncertain possibility). To date, 70.9% of Coloradans have completed a primary series, while only 22.4% of those eligible have received a bivalent booster. 
The “tripledemic” is still receiving attention. Fortunately, respiratory syncytial virus (RSV) is declining in Colorado in parallel with the national trend. Influenza is still circulating widely, but surveillance data suggest a possible plateau. With the state’s influenza vaccination rate at 54.7%, Colorado will still benefit if the unvaccinated seek a flu shot. Optimistically, Colorado has avoided a tripledemic that would have strained healthcare capacity.  
We are nearing the three-year mark for the pandemic and facing an uncertain future that will depend on the mutational whims of SARS-CoV-2. With a lengthy pandemic ordeal perhaps coming to an endemic end, now is the right time for a full assessment of lessons learned. Last week, Bill Burman, former director of Denver Public Health, and I published an editorial in the Colorado Sun calling for such an assessment. We stated the obvious, concluding that: “It is time for an integrated and coordinated review of the Colorado COVID-19 response, one that brings the key players to the same table.” In calling for such a review, we note that there are many entities involved in responding to COVID-19 and that all need to be engaged to address and evaluate the underlying “system.” We hone in on topics to be addressed: data and monitoring; health disparities; impact on K-12 education; contact support and contact tracing; congregate living settings, particularly skilled nursing facilities; and coordination of COVID-19 responses across systems. Our call for a comprehensive review is not a criticism, but a reminder that “an integrated and coordinated review” should help to enhance preparedness. Pandemics are not going away, including COVID-19.
One lesson learned and relearned is the need to reduce airborne transmission of infectious agents in indoor spaces. Since we spend most of our day indoors, predominantly in mechanically ventilated environments, interventions to reduce transmission could substantially reduce risk for infections. Pioneering work on controlling airborne transmission was carried out by Wells and Riley as early as the 1930s. Subsequently, the science advanced little until the COVID-19 pandemic. Now, we have a core package of measures that will reduce airborne transmission: increasing ventilation to dilute the concentration of pathogens; filtration to remove pathogens; and ultraviolet C irradiation to kill pathogens.
Last week, key publications were released that address these measures and steps to implement them. The Lancet COVID-19 Commission published recommendations for ventilation rates for reducing airborne infection. The commission’s members review the literature, including the work of relevant organizations, and use expert judgment to propose three tiered levels of ventilation purported to provide “good,” “better,” or “best” control. The American Society for Heating, Ventilating, and Air Conditioning Engineers (ASHRAE) develops standards for ventilation that are widely applied and become the basis for building code. Last week, ASHRAE committed to developing a pathogen mitigation standard that could be enforced. In the 1990s, I served on ASHRAE’s committee for its Ventilation Standard 62: Ventilation for Acceptable Indoor Air Quality when there was controversy as to whether acceptable indoor air quality could be achieved if there was smoking. The answer was no, following a tough struggle with the tobacco industry and its surrogates. Developing a pathogen mitigation standard is needed but producing one will be challenging. Good luck to this committee of volunteers. Last, the White House issued a fact sheet declaring its commitment to cleaner indoor air across the nation
We continue to rediscover the significance of indoor air for public health. Not surprisingly, since people in higher income countries spend most of their time in indoor environments, contamination of indoor air by chemicals and pathogens can have a powerful impact on health, causing disease and harming public health. With my Harvard colleague, John Spengler, I edited one of the early books on the topic, Indoor Air Pollution: A Health Perspective. With John McCarthy, we edited a 1,500-page book, Indoor Air Quality Handbook. A trio of editors with fortitude put together a recently published 2,200-page update. My point here, other than marketing my old books, is that knowledge of indoor air pollution is voluminous. Implementation of what we know is deficient. I wait to see if the pandemic will spark action or just reports. 
We continue to substantiate that vaccination is critical, whether to eradicating smallpox or curbing COVID-19. In a regressive move, suitable for COVID follies acknowledgement, the recently passed bill to fund defense also rescinds mandatory vaccination against SARS-CoV-2 for the military. The reversal of vaccination policy acquiesced to Republican demands and assertions that the vaccine requirement was harming recruiting. Many vaccinations are mandated for military members and are critical to assuring health and readiness of the Armed Forces. Those pushing to rescind the mandate should read John Barry’s The Great Influenza, which documents the 1918 pandemic’s toll on young recruits and its impact on troops traveling by ship to Europe. Politics should not reach into vaccination of the military. The pernicious influence of political considerations on pandemic control is a lesson repeatedly learned since March 2020.  
Jonathan Samet, MD, MS
Dean, Colorado School of Public Health
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