Protection from Omicron Infection in Residents of Nursing and Retirement Homes in Ontario, Canada.

OBJECTIVES: To identify factors that contribute to protection from infection with the Omicron variant of SARS-CoV-2 in older adults in nursing and retirement homes. DESIGN: Longitudinal cohort study with retrospective analysis of infection risk. SETTING AND PARTICIPANTS: 997 residents of nursing and retirement homes from Ontario, Canada, in the COVID in LTC study. METHODS: Residents with 3 messenger RNA (mRNA) dose vaccinations were included in the study. SARS-CoV-2 infection was determined by positive nasopharyngeal polymerase chain reaction test and/or circulating antinucleocapsid IgG antibodies. Cumulative probability of Omicron infection after recent COVID-19 was assessed by log-rank test of Kaplan-Meier curves. Cox regression was used to assess risk of Omicron infection by age, sex, mRNA vaccine combination, whether individuals received a fourth dose, as well as recent COVID-19. RESULTS: In total, 171 residents (17.2%) had a presumed Omicron variant SARS-CoV-2 infection between December 15, 2021 (local start of the first Omicron wave) and May 3, 2022. Risk of Omicron infection was not different by age [hazard ratio (95% confidence interval) 1.01 (0.99‒1.02)], or in women compared with men [0.97 (0.70‒1.34)], but infection risk decreased 47% with 3 vaccine doses of mRNA-1273 (Moderna) compared with BNT162b2 (Pfizer) [0.53 (0.31-0.90)], 81% with any fourth mRNA vaccine dose [0.19 (0.12‒0.30)], and 48% with SARS-CoV-2 infection in the 3 months prior to beginning of the Omicron wave [0.52, (0.27‒0.99)]. CONCLUSIONS AND IMPLICATIONS: Vaccine type (ie, mRNA-1273/Spikevax vs BNT162b2/Cominarty), any fourth vaccine dose, and hybrid immunity from recent COVID-19, were protective against infection with the Omicron variant. These data emphasize the importance of vaccine type, and number of vaccine doses, in maintenance of protective immunity and reduction of risk of Omicron variant breakthrough infection. These findings promote continued public health efforts to support vaccination programs and monitor vaccine immunogenicity in older adults.

Older Age and Frailty are Associated with Higher Mortality but Lower ICU Admission with COVID-19.

Background: We report characteristics and outcomes of adults admitted to Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) Network hospitals with COVID-19 in 2020. Methods: Patients with laboratory-confirmed COVID-19 admitted to 11 sites in Ontario, Quebec, Alberta, and Nova Scotia up to December 31, 2020 were enrolled in this prospective observational cohort study. Measures included age, sex, demographics, housing, exposures, Clinical Frailty Scale, comorbidities; in addition, length of stay, intensive care unit (ICU) admission, mechanical ventilation, and survival were assessed. Descriptive analyses and multivariable logistic regressions were conducted. Results: Among 2,011 patients, mean age was 71.0 (range 19-105) years. 29.7% were admitted from assisted living or long-term care facilities. The full spectrum of frailty was represented in both younger and older age groups. 81.8% had at least one underlying comorbidity and 27.2% had obesity. Mortality was 14.3% without ICU admission, and 24.6% for those admitted to ICU. Older age and frailty were independent predictors of lower ICU use and higher mortality; accounting for frailty, obesity was not an independent predictor of mortality, and associations of comorbidities with mortality were weakened. Conclusions: Frailty is a critical clinical factor in predicting outcomes of COVID-19, which should be considered in research and clinical settings.

Influenza surveillance case definitions miss a substantial proportion of older adults hospitalized with laboratory-confirmed influenza: A report from the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) Network.

OBJECTIVE: Older adults often have atypical presentation of illness and are particularly vulnerable to influenza and its sequelae, making the validity of influenza case definitions particularly relevant. We sought to assess the performance of influenza-like illness (ILI) and severe acute respiratory illness (SARI) criteria in hospitalized older adults. DESIGN: Prospective cohort study. SETTING: The Serious Outcomes Surveillance Network of the Canadian Immunization Research Network undertakes active surveillance for influenza among hospitalized adults. METHODS: Data were pooled from 3 influenza seasons: 2011/12, 2012/13, and 2013/14. The ILI and SARI criteria were defined clinically, and influenza was laboratory confirmed. Frailty was measured using a validated frailty index. RESULTS: Of 11,379 adult inpatients (7,254 aged ≥65 years), 4,942 (2,948 aged ≥65 years) had laboratory-confirmed influenza. Their median age was 72 years (interquartile range [IQR], 58-82) and 52.6% were women. The sensitivity of ILI criteria was 51.1% (95% confidence interval [CI], 49.6-52.6) for younger adults versus 44.6% (95% CI, 43.6-45.8) for older adults. SARI criteria were met by 64.1% (95% CI, 62.7-65.6) of younger adults versus 57.1% (95% CI, 55.9-58.2) of older adults with laboratory-confirmed influenza. Patients with influenza who were prefrail or frail were less likely to meet ILI and SARI case definitions. CONCLUSIONS: A substantial proportion of older adults, particularly those who are frail, are missed by standard ILI and SARI case definitions. Surveillance using these case definitions is biased toward identifying younger cases, and does not capture the true burden of influenza. Because of the substantial fraction of cases missed, surveillance definitions should not be used to guide diagnosis and clinical management of influenza.

Considering Frailty in SARS-CoV-2 Vaccine Development: How Geriatricians Can Assist.

The COVID-19 pandemic has disproportionately impacted frail older adults, especially residents of long-term care (LTC) facilities. This has appropriately led to prioritization of frail older adults and LTC residents, and those who care for them, in the vaccination effort against COVID-19. Older adults have distinct immunological, clinical, and practical complexity, which can be understood through a lens of frailty. Even so, frailty has not been considered in studies of COVID-19 vaccines to date, leading to concerns that the vaccines have not been optimally tailored for and evaluated in this population even as vaccination programs are being implemented. This is an example of how vaccines are often not tested in Phase 1/2/3 clinical trials in the people most in need of protection. We argue that geriatricians, as frailty specialists, have much to contribute to the development, testing and implementation of COVID-19 vaccines in older adults. We discuss roles for geriatricians in ten stages of the vaccine development process, covering vaccine design, trial design, trial recruitment, establishment and interpretation of illness definitions, safety monitoring, consideration of relevant health measures such as frailty and function, analysis methods to account for frailty and differential vulnerability, contributions in regulatory and advisory roles, post-marketing surveillance, and program implementation and public health messaging. In presenting key recommendations pertinent to each stage, we hope to contribute to a dialogue on how to push the field of vaccinology to embrace the complexity of frailty. Making vaccines that can benefit frail older adults will benefit everyone in the fight against COVID-19.

COVID-19, frailty and long-term care: Implications for policy and practice.

Older adults have been disproportionately affected by the COVID-19 pandemic, with many outbreaks occurring in Long Term Care Facilities (LTCFs). We discuss this vulnerability among LTCF residents using an ecological framework, on levels spanning from the individual to families and caregivers, institutions, health services and systems, communities, and contextual government policies. Challenges abound for fully understanding the burden of COVID-19 in LTCF, including differences in nomenclature, data collection systems, cultural differences, varied social welfare models, and (often) under-resourcing of the LTC sector. Registration of cases and deaths may be limited by testing capacity and policy, record-keeping and reporting procedures. Hospitalization and death rates may be inaccurate depending on atypical presentations and whether or not residents' goals of care include escalation of care and transfer to hospital. Given the important contribution of frailty, use of the Clinical Frailty Scale (CFS) is discussed as a readily implementable measure, as are lessons learned from the study of frailty in relation to influenza. Biomarkers hold emerging promise in helping to predict disease severity and address the puzzle of why some frail LTCF residents are resilient to COVID-19, either remaining test-negative despite exposure or having asymptomatic infection, while others experience the full range of illness severity including critical illness and death. Strong and coordinated surveillance and research focused on LTCFs and their frail residents is required. These efforts should include widespread assessment of frailty using feasible and readily implementable tools such as the CFS, and rigorous reporting of morbidity and mortality in LTCFs.