Durability of mRNA-1273 against COVID-19 in the time of Delta: Interim results from an observational cohort study
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Abstract
We conducted a prospective cohort study at Kaiser Permanente Southern California to study the vaccine effectiveness (VE) of mRNA-1273 over time and during the emergence of the Delta variant.
Methods
The cohort for this planned interim analysis consisted of individuals aged ≥18 years receiving 2 doses of mRNA-1273 through June 2021, matched 1:1 to randomly selected unvaccinated individuals by age, sex, and race/ethnicity, with follow-up through September 2021. Outcomes were SARS-CoV-2 infection, and COVID-19 hospitalization and hospital death. Cox proportional hazards models were used to estimate adjusted hazard ratios (aHR) with 95% confidence intervals (CIs) comparing outcomes in the vaccinated and unvaccinated groups. Adjusted VE (%) was calculated as (1-aHR)x100. HRs and VEs were also estimated for SARS-CoV-2 infection by age, sex, race/ethnicity, and during the Delta period (June-September 2021). VE against SARS-CoV-2 infection and COVID-19 hospitalization was estimated at 0-<2, 2-<4, 4-<6, and 6-<8 months post-vaccination.
Results
927,004 recipients of 2 doses of mRNA-1273 were matched to 927,004 unvaccinated individuals. VE (95% CI) was 82.8% (82.2–83.3%) against SARS-CoV-2 infection, 96.1% (95.5–96.6%) against COVID-19 hospitalization, and 97.2% (94.8–98.4%) against COVID-19 hospital death. VE against SARS-CoV-2 infection was similar by age, sex, and race/ethnicity, and was 86.5% (84.8–88.0%) during the Delta period. VE against SARS-CoV-2 infection decreased from 88.0% at 0-<2 months to 75.5% at 6-<8 months.
Conclusions
These interim results provide continued evidence for protection of 2 doses of mRNA-1273 against SARS-CoV-2 infection over 8 months post-vaccination and during the Delta period, and against COVID-19 hospitalization and hospital death.
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SciScore for 10.1101/2021.12.13.21267620: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: The KPSC Institutional Review Board reviewed and approved the study. Sex as a biological variable not detected. Randomization Unvaccinated comparators were randomly selected and matched 1:1 to the vaccinated individuals by age group (18–44 years, 45–64 years, 65–74 years, and ≥75 years), sex, and race/ethnicity (Non-Hispanic White, Non-Hispanic Black, Hispanic, Non-Hispanic Asian, and Other/Unknown). Blinding not detected. Power Analysis not detected. Table 2: Resources
Experimental Models: Organisms/Strains Sentences Resources Unvaccinated comparators were randomly selected and matched 1:1 to the vaccinated individuals by age group (18–44 years, 45–64 years, 65–74 years, and ≥75 years), sex, and … SciScore for 10.1101/2021.12.13.21267620: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: The KPSC Institutional Review Board reviewed and approved the study. Sex as a biological variable not detected. Randomization Unvaccinated comparators were randomly selected and matched 1:1 to the vaccinated individuals by age group (18–44 years, 45–64 years, 65–74 years, and ≥75 years), sex, and race/ethnicity (Non-Hispanic White, Non-Hispanic Black, Hispanic, Non-Hispanic Asian, and Other/Unknown). Blinding not detected. Power Analysis not detected. Table 2: Resources
Experimental Models: Organisms/Strains Sentences Resources Unvaccinated comparators were randomly selected and matched 1:1 to the vaccinated individuals by age group (18–44 years, 45–64 years, 65–74 years, and ≥75 years), sex, and race/ethnicity (Non-Hispanic White, Non-Hispanic Black, Hispanic, Non-Hispanic Asian, and Other/Unknown). Non-Hispanic Whitesuggested: NoneSoftware and Algorithms Sentences Resources All analyses were conducted using SAS software version 9.4, Cary, USA. SASsuggested: (SASqPCR, RRID:SCR_003056)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:Misclassification of SARS-CoV-2 infection from false positive or false negative test results or from inaccurate diagnosis codes from outside claims may have been another limitation. This non-differential misclassification could have underestimated the VE. Lastly, individuals vaccinated during the Delta period were younger as vaccines had recently become available to the general population and may have had fewer COVID-19 risk factors, which could have led to overestimation of VE during the Delta period. In conclusion, this second interim analysis of an ongoing cohort study found that VE of 2 doses of mRNA-1273 against SARS-CoV-2 infection declined moderately over the course of 8 months, but VE against COVID-19 hospitalization remained robust and stable over the same period. In addition, VE against SARS-CoV-2 infection in newly vaccinated individuals during the Delta period remained high. Continued long-term follow-up is needed to fully evaluate the real-world effectiveness of mRNA-1273 overall and in different subgroups of the population over time.
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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