THURSDAY, Aug. 24, 2023 (HealthDay News) -- Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) omicron infection is associated with an increased risk for reinfection among residents of long-term care and retirement homes, according to a study published online Aug. 21 in eClinicalMedicine.
Jessica A. Breznik, Ph.D., from McMaster University in Hamilton, Ontario, Canada, and colleagues examined the incidence of SARS-CoV-2 Omicron infection in 750 vaccinated residents of long-term care and retirement homes in an observational study within July to September 2022. In a subset of 318 residents, serum anti-spike and anti-receptor binding domain (RBD) SARS-CoV-2 immunoglobulin (Ig)G and IgA antibodies, microneutralization titers, and spike-specific T-cell memory responses were examined within the preceding three months.
The researchers found that during the observation period, 17.7 percent of the 750 participants had a polymerase chain reaction-confirmed omicron infection. There was an association for increased infection risk with prior omicron infection (at nine to 29 days: 47.67, which was not attributed to days since fourth vaccination or residence outbreaks). After their initial omicron infection, reinfected participants had lower serum neutralizing antibodies to ancestral and omicron BA.1 SARS-CoV-2 and lower anti-RBD IgG and IgA antibodies.
"Overall, our observations caution that immunological features of hybrid immunity are not the same in all older adults, and hybrid immunity should not be considered a panacea against future SARS-CoV-2 infection, whether from cross-subvariant Omicron infections, or future variants of concern," the authors write.
Two authors disclosed ties to the pharmaceutical industry.
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