Laboratory-Confirmed COVID-19 Case Incidence Rates Among Residents in Nursing Homes by Up-to-Date Vaccination Status — United States, October 10, 2022–January 8, 2023

Nursing home residents have been disproportionately affected by COVID-19; older age, comorbidities, and the congregate nature of nursing homes place residents at higher risk for infection and severe COVID-19–associated outcomes, including death (1). Studies have demonstrated that receipt of a primary COVID-19 mRNA vaccination series (2) and monovalent booster doses (3) is effective in reducing COVID-19–related morbidity and mortality in this population. Public health recommendations for staying up to date with COVID-19 vaccination have been revised throughout the pandemic response, most recently to include an updated (bivalent) booster dose, which protects against both the ancestral strain of SARS-CoV-2 and recent Omicron variants BA.4 and BA.5 (4). However, data on the effectiveness of staying up to date, including with bivalent booster doses, are lacking among nursing home residents. CDC’s National Healthcare Safety Network (NHSN) analyzed surveillance data to examine weekly incidence rates of COVID-19 among nursing home residents by up-to-date vaccination status (receipt of a bivalent booster dose or completion of a primary series or receipt of a monovalent booster dose within the previous 2 months [i.e., not yet eligible to receive a bivalent booster dose]).* Up-to-date vaccination status among nursing home residents remained low throughout the study period, increasing to 48.9% by the week ending January 8, 2023. During October 10, 2022–January 8, 2023, the COVID-19 weekly incidence rates (new cases per 1,000 nursing home residents) among residents who were not up to date with COVID-19 vaccination were consistently higher than those among residents who were up to date. Moreover, the weekly incidence rate ratios (IRRs) indicated that residents who were not up to date with COVID-19 vaccines had a higher risk for acquiring SARS-CoV-2 than their up-to-date counterparts (IRR range = 1.3–1.5). It is critical that nursing home residents stay up to date with COVID-19 vaccines and receive a bivalent booster dose to maximize protection against COVID-19.

Nursing homes began reporting numbers of laboratory-confirmed COVID-19 cases (a newly positive SARS-CoV-2 viral test result received by a resident) and vaccination data to NHSN in April 2020 and December 2020, respectively, and federal mandates issued by the Centers for Medicare & Medicaid Services (CMS) require CMS-certified nursing homes to report these data weekly.^†,§ The method for collecting laboratory-confirmed COVID-19 case data in nursing homes has been described (2). Vaccination data collection includes the weekly number of residents in the nursing home (with a stay of ≥24 hours) stratified by vaccination status, including the number of residents who are up to date with recommended COVID-19 vaccination.

NHSN analyzed weekly COVID-19 case and vaccination status data during October 10, 2022–January 8, 2023, for CMS-certified nursing homes to assess the data collected based on NHSN’s 2022 fourth quarter (October–December) definition of up-to-date COVID-19 vaccination status.^¶ The study paired weekly incident case counts by vaccination status with weekly resident counts by vaccination status for each nursing home to calculate crude COVID-19 incidence rates with 95% CIs, by up-to-date vaccination status for each reporting week. Case counts were combined with resident vaccination counts from 2 weeks earlier, because COVID-19 case vaccination status is classified according to vaccination status 14 days before receipt of a positive SARS-CoV-2 test result.

Facilities with missing case or vaccination data were excluded from the analysis. NHSN calculated IRRs by up-to-date vaccination status each week. NHSN also analyzed a subset of data from facilities voluntarily reporting dates, types, and number of primary series doses and booster doses received by each resident (rather than weekly aggregate totals) to calculate the proportion of up-to-date residents who had received a bivalent booster dose.** Analyses were performed using SAS software (version 9.4; SAS Institute). This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.^††

Among 16,352 nursing homes, 15,049 (92%) in the 50 U.S. states and the District of Columbia reported case and vaccination data for ≥1 week during the 13-week study period.^§§ After exclusions, 192,289 facility-weeks (97%) were included in the analysis. An average of 14,791 facilities reported both COVID-19 vaccination and case data each week (range = 14,622–14,874). Facility size (the number of health care personnel per facility) varied, with a median of 116 health care personnel per facility (IQR = 82–165) (Figure). The percentage of residents with up-to-date COVID-19 vaccination status increased slightly during the study period, beginning the week of October 23, from 37.5% to 48.9%; this incremental increase was similar across all facility sizes and geographic regions.

Each week, COVID-19 incidence rates among nursing home residents who were not up to date with COVID-19 vaccination were higher than those among residents who were up to date (Table). Incidence rates among residents who were up to date with COVID-19 vaccination ranged from 7.2 per 1,000 residents (week ending November 13, 2022) to 15.6 (week ending January 8, 2023) during this period, while incidence rates among those who were not up to date ranged from 9.5 (week ending October 16, 2022) to 18.8 (weeks ending December 11, 2022, and January 8, 2023). IRRs between residents who were not up to date with COVID-19 vaccination and those who were up to date were statistically significant and ranged from 1.3 to 1.5. Among the 15,049 nursing homes included in this study, 1,759 (11.7%) voluntarily reported additional details on vaccine doses for each resident rather than weekly aggregate totals. Analysis of these data for each week of the study period indicated that >99% of residents classified as being up to date had received a bivalent booster dose.

Acknowledgments

Audrey Robnett-Brown, Sherese Dennard, Emily Haanschoten, Elizabeth Kalayil, Avni Patel, George Segovia, Shanjeeda Shafi, Jolie Siegel, CDC National Healthcare Safety Network Vaccination Unit Team.

Corresponding author: Heather Dubendris, [email protected].

¹Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases, CDC; ²Lantana Consulting Group, East Thetford, Vermont; ³Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, CDC.

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FIGURE. Percentage of nursing home residents with up-to-date COVID-19 vaccination,* by U.S. region, number of health care personnel per facility,^† and week^§ — United States, October 10, 2022–January 8, 2023

Abbreviation: UTD = up to date with COVID-19 vaccines.

* Receipt of a bivalent booster dose or completion of a primary series or receipt of a monovalent booster dose within the previous 2 months (i.e., not yet eligible to receive a bivalent booster dose).

^† Used as an estimate of facility size.

^§ For each reporting week, vaccination data from 2 weeks earlier are included to allow for appropriate incidence rate calculation.

Abbreviation: UTD = up to date with COVID-19 vaccines.
* For each reporting week, total residents by vaccination status from 2 weeks earlier are included to allow for appropriate incidence rate calculation.
^† New cases per 1,000 nursing home residents.
^§ Receipt of a bivalent booster dose or completion of a primary series or receipt of a monovalent booster dose within the previous 2 months (i.e., not yet eligible to receive a bivalent booster dose).
^¶ Incidence rate ratios are calculated as the incidence rate among residents who were not UTD divided by the incidence rate among residents who were UTD; 95% CIs calculated using Mid-P.