tetano
Editor, Senior Moderator
Clin Infect Dis
. 2022 Apr 27;ciac327.
doi: 10.1093/cid/ciac327. Online ahead of print.
Coronavirus Disease 2019 (COVID-19) Vaccine Boosting in Previously Infected or Vaccinated Individuals
Nabin K Shrestha[SUP] 1 [/SUP], Priyanka Shrestha[SUP] 2 [/SUP], Patrick C Burke[SUP] 3 [/SUP], Amy S Nowacki[SUP] 4 [/SUP], Paul Terpeluk[SUP] 5 [/SUP], Steven M Gordon[SUP] 1 [/SUP]
Affiliations
Abstract
Background: The purpose of this study was to evaluate whether boosting previously infected or vaccinated healthcare personnel with a vaccine developed for an earlier variant of SARS-CoV-2 protects against the Omicron variant.
Methods: Employees of Cleveland Clinic previously infected with or vaccinated against COVID-19, and working in Ohio the day the Omicron variant was declared a variant of concern, were included. The cumulative incidence of COVID-19 was examined over two months during an Omicron variant surge. Protection provided by boosting (analyzed as a time-dependent covariate) was evaluated using Cox proportional hazards regression. Analyses were adjusted for time since proximate SARS-CoV-2 exposure as a time-dependent covariate.
Results: Among 39 766 employees, 8037 (20%) previously infected and the remaining previously vaccinated, COVID-19 occurred in 6230 (16%) during the study. Risk of COVID-19 increased with time since proximate SARS-CoV-2 exposure, and boosting protected those >6 months since prior infection or vaccination. In multivariable analysis, boosting was independently associated with lower risk of COVID-19 among those vaccinated but not previously infected (HR, .43; 95% CI, .41-.46) as well as those previously infected (HR, .66; 95% CI, .58-.76). Among those previously infected, receiving 2 compared to 1 dose of vaccine was associated with higher risk of COVID-19 (HR, 1.54; 95% CI, 1.21-1.97).
Conclusions: Administering a COVID-19 vaccine not designed for the Omicron variant, >6 months after prior infection or vaccination, protects against Omicron variant infection in those previously infected or vaccinated. There is no evidence of an advantage to administering more than 1 dose of vaccine to previously infected persons.
Keywords: COVID-19; SARS-CoV-2; immunity; incidence; vaccines.
. 2022 Apr 27;ciac327.
doi: 10.1093/cid/ciac327. Online ahead of print.
Coronavirus Disease 2019 (COVID-19) Vaccine Boosting in Previously Infected or Vaccinated Individuals
Nabin K Shrestha[SUP] 1 [/SUP], Priyanka Shrestha[SUP] 2 [/SUP], Patrick C Burke[SUP] 3 [/SUP], Amy S Nowacki[SUP] 4 [/SUP], Paul Terpeluk[SUP] 5 [/SUP], Steven M Gordon[SUP] 1 [/SUP]
Affiliations
- PMID: 35476018
- DOI: 10.1093/cid/ciac327
Abstract
Background: The purpose of this study was to evaluate whether boosting previously infected or vaccinated healthcare personnel with a vaccine developed for an earlier variant of SARS-CoV-2 protects against the Omicron variant.
Methods: Employees of Cleveland Clinic previously infected with or vaccinated against COVID-19, and working in Ohio the day the Omicron variant was declared a variant of concern, were included. The cumulative incidence of COVID-19 was examined over two months during an Omicron variant surge. Protection provided by boosting (analyzed as a time-dependent covariate) was evaluated using Cox proportional hazards regression. Analyses were adjusted for time since proximate SARS-CoV-2 exposure as a time-dependent covariate.
Results: Among 39 766 employees, 8037 (20%) previously infected and the remaining previously vaccinated, COVID-19 occurred in 6230 (16%) during the study. Risk of COVID-19 increased with time since proximate SARS-CoV-2 exposure, and boosting protected those >6 months since prior infection or vaccination. In multivariable analysis, boosting was independently associated with lower risk of COVID-19 among those vaccinated but not previously infected (HR, .43; 95% CI, .41-.46) as well as those previously infected (HR, .66; 95% CI, .58-.76). Among those previously infected, receiving 2 compared to 1 dose of vaccine was associated with higher risk of COVID-19 (HR, 1.54; 95% CI, 1.21-1.97).
Conclusions: Administering a COVID-19 vaccine not designed for the Omicron variant, >6 months after prior infection or vaccination, protects against Omicron variant infection in those previously infected or vaccinated. There is no evidence of an advantage to administering more than 1 dose of vaccine to previously infected persons.
Keywords: COVID-19; SARS-CoV-2; immunity; incidence; vaccines.