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To the Editor
White et al. (July 29 issue)1 provided interesting data on the effectiveness of messenger RNA vaccines in reducing the incidence of SARS-CoV-2 infection in a vulnerable nursing home population. The study showed that there were similar decreases in SARS-CoV-2 infection (asymptomatic and symptomatic) in the vaccinated population and in the unvaccinated population. The authors attributed the decrease in infection in the vaccinated group to vaccine protection and attributed the similar decrease in the unvaccinated group to robust vaccine coverage among residents and staff, together with the use of masks and infection-control measures. This appears to be in contradiction to the authors’ description of Table S3 in the Supplementary Appendix of their letter (available at NEJM.org), which indicated that they found no consistent relationship between the incidence of infection among residents and vaccination rates among the staff (a finding also acknowledged in the text of their letter).
The fact that the residents in the vaccinated group were also using masks and following infection-control measures and the fact that the decline in infection was similar in the two groups raise the question of how much added protective effect was provided by vaccines in this study. The efficacy of masks in providing protection against infection and death is well documented.2-4 It is of note that both hospitalizations mentioned in the footnote of Table 1 in their letter were in the vaccinated group.
Baskaran Chandrasekar, M.D.
Chest Diseases Hospital, Kuwait, Kuwait
[email protected]
No potential conflict of interest relevant to this letter was reported.
This letter was published on October 13, 2021, at NEJM.org.
1. White EM, Yang X, Blackman C, Feifer RA, Gravenstein S, Mor V. Incident SARS-CoV-2 infection among mRNA vaccinated and unvaccinated nursing home residents. N Engl J Med 2021;385:474–476.
2. Mitze T, Kosfeld R, Rode J, Wälde K. Face masks considerably reduce COVID-19 cases in Germany. Proc Natl Acad Sci U S A 2020;117:32293–32301.
3. Chernozhukov V, Kasahara H, Schrimpf P. Causal impact of masks, policies, behavior on early Covid-19 pandemic in the U.S. J Econom 2021;220:23–62.
4. Peeples L. Face masks: what the data say. Nature 2020;586:186–189.
Response
Elizabeth M. White, Ph.D., A.P.R.N.
Vincent Mor, Ph.D.
Brown University School of Public Health, Providence, RI
[email protected]
Since publication of their letter, the authors report no further potential conflict of interest.
This letter was published on October 13, 2021, at NEJM.org.
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