SARS-CoV-2 Infection among Nursing Home Residents


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

No potential conflict of interest relevant to this letter was reported.

This letter was published on October 13, 2021, at NEJM.org.

  1. 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;385:474476.

  2. 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;117:3229332301.

  3. 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;220:2362.

  4. 4. Peeples L. Face masks: what the data say. Nature 2020;586:186189.

Response

The authors reply: As noted in our letter, we used descriptive data that included incident cases through March 31, 2021. This was a period during which the incidence of infection dropped precipitously across U.S. nursing homes, leaving little room to make reasonable comparisons across facilities on the basis of staff vaccination rates, since the number of new infections was so low. In addition, even among the nursing homes in the lowest third for staff vaccination rates in our sample, almost all had at least half their staff vaccinated, and most residents were vaccinated. These factors, combined with the continued use of face masks, frequent testing, and other infection-control measures, are likely to explain the inconsistent patterns related to staff vaccination rates in our original data. We continue to monitor these trends during the current surge in B.1.617.2 (delta) variant infections and as we learn more about waning immunity in this population.

Elizabeth M. White, Ph.D., A.P.R.N.
Vincent Mor, Ph.D.
Brown University School of Public Health, Providence, RI

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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