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Published on: July 24, 2013
Frailty Reduces Vaccine Effectiveness Against SARS-CoV-2 Infection: A Test-Negative Case Control Study Using National
F Tang1, I S Hammel, M K Andrew
1Fei Tang, Ph.D., Geriatric Research Education and Clinical Center, Miami VA Healthcare System, 1201 NW 16th Street, Miami, FL, USA, 33125, Email: fei.tang@va.gov, Phone: 305-575-3388.
Objectives:
To assess the variation of vaccine effectiveness against SARS-CoV-2 infection during the Delta wave according to frailty status among U.S. veterans.
Design:
Test-negative case-control study of SARS-CoV-2 mRNA vaccine effectiveness.
Setting:
Veterans Health Administration (VHA) medical centers.
Participants:
Veterans 19 years and older who had at least one COVID-19/Flu like symptoms and received a SARS-CoV-2 PCR or antigen test at VHA medical centers between July 25 to September 30, 2021.
Intervention:
mRNA vaccination.
Measurements:
New SARS-CoV-2 infection. Vaccine effectiveness was defined as 1-odds of vaccination in cases/odds of vaccination in controls, where cases were patients who had a COVID-19 test and tested positive for SARS-CoV-2, and controls were those who tested negative. Frailty was measured using the VA frailty index, categorized as robust (0-<0.1), pre-frail (≥0.1-<0.21) and frail (≥0.21).
Results:
A total of 58,604 patients (age:58.9±17.0, median:61, IQR:45-72; 87.5%men; 68.1%white; 1.3%African American, 8.3%Hispanic) were included in the study. Of these, 27,733 (47.3%) were robust, 16,276 (27.8%) were prefrail, and 14,595 (24.9%) were frail. mRNA vaccine effectiveness against the Delta variant symptomatic infection was lower in patients with frailty, 62.8 %(95%CI:59.8-65.7), versus prefrail 73.9%(95%CI:72.0-75.7), and robust, 77.0 %(95%CI:75.7-78.3).
Conclusions:
This test-negative case control study showed that mRNA vaccine effectiveness against infection declined in veterans with frailty. Frailty status is a factor to consider when designing, developing, and evaluating COVID-19 vaccines.
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