tetano
Editor, Senior Moderator
Eur J Clin Invest
. 2023 Nov 30:e14136.
doi: 10.1111/eci.14136. Online ahead of print. Effectiveness of a fourth SARS-CoV-2 vaccine dose in previously infected individuals from Austria
Alena Chalupka[SUP] 1 [/SUP], Lukas Richter[SUP] 1 2 [/SUP], Ali Chakeri[SUP] 1 3 [/SUP], Ziad El-Khatib[SUP] 1 [/SUP], Verena Theiler-Schwetz[SUP] 4 [/SUP], Christian Trummer[SUP] 4 [/SUP], Robert Krause[SUP] 5 [/SUP], Peter Willeit[SUP] 6 7 8 [/SUP], Bernhard Benka[SUP] 1 [/SUP], John P A Ioannidis[SUP] 9 [/SUP], Stefan Pilz[SUP] 4 [/SUP]
Affiliations
Introduction: Evidence is limited on the effectiveness of a fourth vaccine dose against coronavirus disease 2019 (COVID-19) in populations with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. We estimated the risk of COVID-19 deaths and SARS-CoV-2 infections according to vaccination status in previously infected individuals in Austria.
Methods: This is a nationwide retrospective observational study. We calculated age and gender adjusted Cox proportional hazard ratios (HRs) of COVID-19 deaths (primary outcome) and SARS-CoV-2 infections (secondary outcome) from 1 November to 31 December 2022, primarily comparing individuals with four versus three vaccine doses. Relative vaccine effectiveness (rVE) was calculated as (1-HR) X 100.
Results: Among 3,986,312 previously infected individuals, 281,291 (7,1%) had four and 1,545,242 (38.8%) had three vaccinations at baseline. We recorded 69 COVID-19 deaths and 89,056 SARS-CoV-2 infections. rVE for four versus three vaccine doses was -24% (95% CI: -120 to 30) against COVID-19 deaths, and 17% (95% CI: 14-19) against SARS-CoV-2 infections. This latter effect rapidly diminished over time and infection risk with four vaccinations was higher compared to less vaccinated individuals during extended follow-up until June 2023. Adjusted HR (95% CI) for all-cause mortality for four versus three vaccinations was 0.79 (0.74-0.85).
Discussion: In previously infected individuals, a fourth vaccination was not associated with COVID-19 death risk, but with transiently reduced risk of SARS-CoV-2 infections and reversal of this effect in longer follow-up. All-cause mortality data suggest healthy vaccinee bias.
Keywords: COVID-19; SARS-CoV-2; booster; mortality; national; vaccine.
. 2023 Nov 30:e14136.
doi: 10.1111/eci.14136. Online ahead of print. Effectiveness of a fourth SARS-CoV-2 vaccine dose in previously infected individuals from Austria
Alena Chalupka[SUP] 1 [/SUP], Lukas Richter[SUP] 1 2 [/SUP], Ali Chakeri[SUP] 1 3 [/SUP], Ziad El-Khatib[SUP] 1 [/SUP], Verena Theiler-Schwetz[SUP] 4 [/SUP], Christian Trummer[SUP] 4 [/SUP], Robert Krause[SUP] 5 [/SUP], Peter Willeit[SUP] 6 7 8 [/SUP], Bernhard Benka[SUP] 1 [/SUP], John P A Ioannidis[SUP] 9 [/SUP], Stefan Pilz[SUP] 4 [/SUP]
Affiliations
- PMID: 38032853
- DOI: 10.1111/eci.14136
Introduction: Evidence is limited on the effectiveness of a fourth vaccine dose against coronavirus disease 2019 (COVID-19) in populations with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. We estimated the risk of COVID-19 deaths and SARS-CoV-2 infections according to vaccination status in previously infected individuals in Austria.
Methods: This is a nationwide retrospective observational study. We calculated age and gender adjusted Cox proportional hazard ratios (HRs) of COVID-19 deaths (primary outcome) and SARS-CoV-2 infections (secondary outcome) from 1 November to 31 December 2022, primarily comparing individuals with four versus three vaccine doses. Relative vaccine effectiveness (rVE) was calculated as (1-HR) X 100.
Results: Among 3,986,312 previously infected individuals, 281,291 (7,1%) had four and 1,545,242 (38.8%) had three vaccinations at baseline. We recorded 69 COVID-19 deaths and 89,056 SARS-CoV-2 infections. rVE for four versus three vaccine doses was -24% (95% CI: -120 to 30) against COVID-19 deaths, and 17% (95% CI: 14-19) against SARS-CoV-2 infections. This latter effect rapidly diminished over time and infection risk with four vaccinations was higher compared to less vaccinated individuals during extended follow-up until June 2023. Adjusted HR (95% CI) for all-cause mortality for four versus three vaccinations was 0.79 (0.74-0.85).
Discussion: In previously infected individuals, a fourth vaccination was not associated with COVID-19 death risk, but with transiently reduced risk of SARS-CoV-2 infections and reversal of this effect in longer follow-up. All-cause mortality data suggest healthy vaccinee bias.
Keywords: COVID-19; SARS-CoV-2; booster; mortality; national; vaccine.