High vaccine effectiveness against severe COVID-19 in the elderly in Finland before and after the emergence of Omicron
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Abstract
Background
The elderly are highly vulnerable to severe COVID-19. Waning immunity and emergence of Omicron have caused concerns about reduced effectiveness of COVID-19 vaccines. The objective was to estimate vaccine effectiveness (VE) against severe COVID-19 among the elderly.
Methods
This nationwide, register-based cohort analysis included all residents aged 70 years and over in Finland. The follow-up started on December 27, 2020, and ended on March 31, 2022. The outcomes of interest were COVID-19-related hospitalization and intensive care unit (ICU) admission timely associated with SARS-CoV-2 infection. VE was estimated as one minus the hazard ratio comparing the vaccinated and unvaccinated and taking into account time since vaccination. Omicron-specific VE was evaluated as the effectiveness observed since January 1, 2022.
Results
The cohort included 896,220 individuals. Comirnaty (BioNTech/Pfizer) VE against COVID-19-related hospitalization was 93% (95% CI 89–95%) and 85% (95% CI 82–87%) 14–90 and 91–180 days after the second dose; VE increased to 95% (95% CI 94–96%) 14–60 days after the third dose. VE of other homologous and heterologous three dose series was similar. Protection against severe COVID-19 requiring ICU treatment was even better. Since January 1, 2022, Comirnaty VE was 98% (95% CI 92–99%) and 92% (95% CI 87–95%) 14–90 and 91–180 days after the second and 98% (95% CI 95–99%) 14–60 days after the third dose.
Conclusions
VE against severe COVID-19 is high among the elderly. It waned slightly after two doses, but a third restored the protection. VE against severe COVID-19 remained high even after the emergence of Omicron.
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SciScore for 10.1101/2022.03.11.22272140: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Another limitation is that the data do not allow estimation of variant-specific VE. As a surrogate we stratified the analysis by calendar time and used sequencing data to show which variant dominated each quarter. Due to the recent emergence of Omicron, its …
SciScore for 10.1101/2022.03.11.22272140: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Another limitation is that the data do not allow estimation of variant-specific VE. As a surrogate we stratified the analysis by calendar time and used sequencing data to show which variant dominated each quarter. Due to the recent emergence of Omicron, its effect on VE in Finland can only be studied in the latest quarter. However, to provide timely estimates supporting policy makers, we ended the study prematurely before the end of the quarter reducing the statistical power of this particular analysis.
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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