This is a summary, written by members of the CITF Secretariat, of:

Pasat Z, Breznik JA, Rahim A, Zhang A, Ang J, Kajaks T, Miller MS, Bowdish DME, Costa AP. Examining the association between frailty and antibody neutralization of SARS-CoV-2: a multisite retrospective cohort study. J Am Med Dir Assoc. 2024 Feb 5. doi: 10.1016/j.jamda.2023.12.013

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study, published in the Journal of the American Medical Directors Association, found that the frailty status of long-term care residents did not affect serum neutralizing antibodies against the either the ancestral or the Omicron strain of SARS-CoV-2. This study was led by Dr. Zain Pasat and Dr. Andrew P. Costa in collaboration with Dr. Dawn Bowdish (all from McMaster University).

With conflicting reports on frailty as a potential modifier of vaccine immunogenicity in older adults, these researchers aimed to examine this association in 295 long-term care and retirement home residents who had received four monovalent mRNA SARS-CoV-2 vaccinations. Serum was collected at least seven days after the fourth vaccination between January 13 and November 18, 2022.

Frailty was classified according to basic and instrumental activities of daily living, comorbidities, and health status along the following scale: mild to none (19%), moderate (23%), and severe to terminally ill (58%). Serum was used to measure antibody neutralization levels.

Key findings:

  • No association was found between frailty and neutralizing antibody titres within three months post-vaccination;
  • After adjusting for additional variables such as age, sex, number of days since fourth dose, and time from blood draw to the last confirmed infection, the researchers found no association of frailty with SARS-CoV-2 neutralization, irrespective of infection history; and
  • Younger age and recent SARS-CoV-2 infection (£three months) increased serum antibody neutralization titres. A recent infection resulted in higher titres in males than in females, but confidence intervals were wide.

Although a different or more detailed frailty index may provide additional information, these researchers suggest that their study reveals the complex nature of the relationships between frailty, age, sex, and hybrid immunity in older adults. Recent infection or vaccination and younger age, particularly in females, were associated with increased neutralizing antibodies.