Durability of mRNA-1273 against COVID-19 in the time of Delta: Interim results from an observational cohort study.

Abstract

BACKGROUND:

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.

• Authors: Ana Florea, Lina S Sy, Yi Luo, Lei Qian, Katia J Bruxvoort, Bradley K Ackerson, Gina S Lee, Jennifer H Ku, Julia E Tubert, Yun Tian, Carla A Talarico, Hung Fu Tseng
• Journal: PloS one (PLoS One) Vol. 17 Issue 4 Pg. e0267824 ( 2022) ISSN: 1932-6203 [Electronic] United States
• PMID: 35482785 (Publication Type: Journal Article, Observational Study, Research Support, Non-U.S. Gov't)

Chemical References

• 2019-nCoV Vaccine mRNA-1273

Topics

• 2019-nCoV Vaccine mRNA-1273
• Adolescent
• Adult
• COVID-19 (epidemiology, prevention & control)
• Cohort Studies
• Humans
• Prospective Studies
• SARS-CoV-2 (genetics)