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. 2022 Nov;70(11):3245-3249.
doi: 10.1111/jgs.17996. Epub 2022 Aug 8.

Protective effects of prior third dose mRNA vaccination in rural nursing home residents during SARS-CoV-2 outbreaks

Elizabeth S Rhynold  1 , Samuel Quan  2 , Pamela H Orr  3 , Lisa LaBine  4 , Alexander Singer  4 , Philip D St John  5
Affiliations

Protective effects of prior third dose mRNA vaccination in rural nursing home residents during SARS-CoV-2 outbreaks

Elizabeth S Rhynold et al. J Am Geriatr Soc. 2022 Nov.

Abstract

Background: In Canada, mortality due to SARS-CoV-2 disproportionately impacted residents of nursing homes (NH). In November 2021, NH residents in the Canadian province of Manitoba became eligible to receive three doses of mRNA vaccine but coverage with three doses has not been universal. The objective of this study was to compare the protection from infection conferred by one, two, and three doses of COVID-19 mRNA vaccine compared to no vaccination among residents of nursing homes experiencing SARS-CoV-2 outbreaks.

Methods: Infection Prevention and Control reports from 8 rural nursing homes experiencing outbreaks of SARS-CoV-2 between January 6, 2022, and March 5, 2022, were analyzed. Attack rates and the number needed to vaccinate (NNV) were calculated.

Results: SARS-CoV-2 attack rate was 65% among NH residents not vaccinated, 58% among residents who received 1-2 doses of mRNA COVID-19 vaccine, and 28% among residents who had received 3 vaccine doses. The NNV to prevent one nursing home resident from SARS-CoV-2 infection during an outbreak was 3 for a vaccination with 3 doses and 14 for 1-2 doses of COVID-19 mRNA vaccine. The superiority of receiving the third dose was statistically significant compared to 1-2 doses (Chi-Squared, p < 0.00001).

Conclusions: Nursing home residents who received three doses of COVID-19 mRNA vaccine were at lower risk of SARS-CoV-2 infection compared to those who received 1-2 doses. Our analyses lend support to the protective effects of the third dose of mRNA vaccine for NH residents in the event of a SARS-CoV-2 outbreak.

Keywords: COVID-19 vaccines; SARS-CoV-2; disease outbreaks; mRNA vaccines; nursing homes.

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Conflict of interest statement

Dr. Rhynold is a member of the Manitoba COVID‐19 Vaccine Medical Clinical Advisory Committee (no financial remuneration), a member of the Doctors Manitoba COVID‐19 Vaccine Medical Advisory Committee (honorarium for time participating in committee meetings), and an employee of the Prairie Mountain Health Region. As Interim Personal Care Home Medical Director has been part of the medical support to the Personal Care Home COVID‐19 vaccination roll‐out (no additional remuneration from the vaccination of residents). Dr. St John is a board member of Age and Opportunity (Manitoba), has received speaking fees from McMaster University and the Regional Geriatric Program of Eastern Ontario has research funding from the Canadian Institute for Health Research and consulting fees from the University Health Network/Toronto Rehabilitation Institute. Dr. Quan is a graduate student and resident trainee in the Geriatric Medicine and the Clinician Investigator Program at the University of Manitoba, and received scholarships from the CIHR Canada Graduate Scholarship (Master's), Tri‐Agency Top‐Up Award (Faculty of Graduate Studies, University of Manitoba), and the Dr. Hector Ma Award (Department of Internal Medicine, University of Manitoba). Dr. Singer is the Network Director of the Manitoba Primary Care Research Network (MaPCReN) and a Principal Investigator on research grants funded by IBM, Calian, Research Manitoba, CIHR, and PHAC. Dr. Orr and L. Labine have no conflicts to declare.

Figures

FIGURE 1
FIGURE 1
Percentage of nursing home residents with SARS‐CoV‐2 infection in each of the facilities, stratified by the number of COVID‐19 vaccine doses received. Facilities A through D had more than 50 residents, while in E through H were 50 or fewer residents.
See this image and copyright information in PMC

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