Antibody Responses in Elderly Residential Care Persons following COVID-19 mRNA Vaccination (preprint)

ABSTRACT

Objective COVID-19 disproportionately impacts older adults residing at long-term care facilities. Data regarding antibody response to COVID-19 vaccines in this population is limited. Our objective was to quantify the presence and magnitude of antibody response in older, vaccinated residents at assisted living, personal care, and independent living facilities. Design A cross-sectional quality improvement study was conducted March 15-April 1, 2021 in the Pittsburgh region. Setting and Population Participants were volunteers at assisted living, personal care, and independent living facilities, who received mRNA COVID-19 vaccine. Conditions that obviate immune responses were exclusionary criteria. Methods Sera were collected to measure IgG anti-SARS-CoV-2 antibody level with reflex to total anti-SARS-CoV-2 immunoglobulin levels. Descriptive statistics, Pearson correlation coefficients, and multiple linear regression analysis were performed to evaluate relationships between factors potentially associated with antibody levels. Results All participants (N=70) had received two rounds of vaccination for COVID-19 and were found to have antibodies to SARS-CoV-2. There was wide variation in relative levels of antibodies as determined by extinction coefficients. Antibody levels trended lower in male sex, advanced age, steroid medications, and longer length of time from vaccination. Conclusions and Implications Higher functioning long-term care residents mounted detectable antibody responses when vaccinated with COVID-19 mRNA-based vaccines. This study provides preliminary information on level of population risk of assisted living, personal care, and independent living residents which can inform reopening strategies. Data suggests some degree of immunity is present during the immediate period following vaccination. However, protective effects of such vaccination programs remain to be determined in larger studies. Clinical protection is afforded not just by pre-formed antibody levels, but by ongoing adaptive immunity, which is known to be decreased in older individuals. Thus, the implications of these levels of antibodies in preventing COVID-19 disease must be determined by clinical follow-up.