key: cord-0819378-v22duaxe authors: Mermel, Leonard A. title: The future of masking date: 2021-01-28 journal: Infection control and hospital epidemiology DOI: 10.1017/ice.2020.1439 sha: e59640fe51db7d3ae7cdad75af21cfddd5753ee0 doc_id: 819378 cord_uid: v22duaxe nan To the Editor-The 2 mRNA vaccines now administered in the United States offer >90% protection against symptomatic coronavirus disease 2019 (COVID-19) infection based on published data. How long the protection lasts beyond a few months is uncertain at the present time. There is one report of COVID-19 reinfection in an otherwise healthy adult 6 months after the initial infection despite production of neutralizing antibodies after the first infection. 1 This individual apparently spread COVID-19 while reinfected, likely reflecting viral replication in the nares in the absence of neutralizing antibodies at that site (ie, lack of mucosal immunity). Widespread vaccination will inevitably reduce the COVID-19 reproductive number, thereby changing the transmission dynamics in many parts of the world. However, infection among those unvaccinated and reinfection in unvaccinated and vaccinated individuals remains an ongoing concern. Universal masking, along with other public health measures, slows COVID-19 transmission. 2,3 These interventions have also reduced transmission of other respiratory viruses over the last year, 4 thereby reducing associated morbidity and mortality. 5 The durability of protection against COVID-19 infection after vaccination is unclear, and universal masking is associated with reduced risk of COVID-19 and infection from other respiratory viruses. What will be the role of masking in the future? Universal masking should continue until COVID-19 herd immunity is reached from natural disease and vaccination. Thereafter, particularly during winter months, 6,7 universal masking should continue in congregate settings and other indoor settings where social distancing cannot be maintained and/or the introduction of fresh air introduced into the environment, or filtration of recirculated air, is suboptimal. 8 Mask wearing will be particularly important for those individuals at greatest risk of poor outcomes with COVID-19 infection. 9 By reducing transmission of respiratory viruses, masking should reduce immune selection pressure in infected individuals, and lower the likelihood that severe acute respiratory coronavirus virus 2 (SARS-CoV-2) will become more transmissible in the future. 10 There will be temptation to lower our guard and not follow advice about social distancing and masking after vaccination. However, we must learn from our experience over the past year. Failure to maintain more than a modicum of masking would reflect an inability to learn from the past to improve our lives in the future. Symptomatic SARS-CoV-2 reinfection of a healthcare worker in a Belgian nosocomial outbreak despite primary neutralizing antibody response Respiratory virus shedding in exhaled breath and efficacy of face masks Association of social distancing and masking with risk of COVID-19 The impact of COVID-19 nonpharmaceutical interventions on the future dynamics of endemic infections Hospital-acquired respiratory viral infections: incidence, morbidity, and mortality in pediatric and adult patients Comparison of common respiratory virus peak incidence among varying age groups in Rhode Island Global seasonality of human coronaviruses: a systematic review Small droplet aerosols in poorly ventilated spaces and SARS-CoV-2 transmission People with certain medical conditions Recurrent emergence and transmission of a SARS-CoV-2 spike deletion ΔH69/ΔV70 Acknowledgments.Financial support. No financial support was provided relevant to this article. All authors report no conflicts of interest relevant to this article.