Immunogenicity after 6 months of BNT162b2 vaccination in frail or disabled nursing home residents: The COVID-A Study

J Am Geriatr Soc. 2022 Mar;70(3):650-658. doi: 10.1111/jgs.17620. Epub 2021 Dec 17.

Abstract

Background: There is incomplete information regarding evolution of antibody titers against SARS-CoV-2 after a two-dose strategy vaccination with BNT162b2 in older adults in long-term care facilities (LTCFs) with frailty, disability, or cognitive impairment. We aimed to determine IgG antibody titer loss in older adults in LTCFs.

Methods: This is a multicenter longitudinal cohort study including 127 residents (90 females and 37 males) with a mean age of 82.7 years (range 65-99) with different frailty and disability profiles in two LTCFs in Albacete, Spain. Residents received two doses of BNT162b2 as per label, and antibody levels were determined 1 and 6 months after the second dose. Age, sex, previous history of coronavirus disease 2019 (COVID-19), comorbidity (Charlson Index), performance in activities of daily living (Barthel Index), frailty (FRAIL instrument), and cognitive status were assessed.

Results: The mean antibody titers 1 and 6 months after the second vaccine dose were 32,145 AU/ml (SD 41,206) and 6182 AU/ml (SD 13,316), respectively. Across all participants, the median antibody titer loss measured 77.6% (interquartile range [IQR] 23.8%). Notably, the decline of titers in individuals with pre-vaccination COVID-19 infection was significantly lower than in those without a history of SARS-CoV-2 infection (72.2% vs. 85.3%; p < 0.001). The median titer decrease per follow-up day was 0.47% (IQR 0.14%) and only pre-vaccination COVID-19 was associated with lower rate of antibody decline at 6 months (hazard ratio 0.17; 95% confidence interval 0.07-0.41; p < 0.001). Frailty, disability, older age, cognitive impairment, or comorbidity were not associated with the extent of antibody loss.

Conclusions: Older adults in LTCFs experience a rapid loss of antibodies over the first 6 months after the second dose of BNT162b2 vaccine. Only pre-vaccination COVID-19 is associated with a slower rate of antibody decrease. Our data support immunization with a third dose in this vulnerable, high-risk population.

Keywords: BNT162b2 vaccine; COVID-19; antibody titers; disability; frailty; immunogenicity; nursing homes; older adults.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antibody Formation
  • BNT162 Vaccine / administration & dosage
  • BNT162 Vaccine / immunology*
  • COVID-19 / immunology*
  • COVID-19 / prevention & control*
  • Disabled Persons*
  • Female
  • Frail Elderly*
  • Humans
  • Longitudinal Studies
  • Male
  • Nursing Homes
  • SARS-CoV-2
  • Spain

Substances

  • BNT162 Vaccine