Kaiser Permanente study shows Moderna COVID-19 vaccine is 87% effective in preventing COVID-19 infection, and more than 95% effective in preventing severe COVID-19.
Kaiser Permanente research in Southern California published November 25, 2021, in The Lancet Regional Health – Americas confirmed high Moderna COVID-19 vaccine effectiveness up to 5 months after the second dose. Effectiveness was 87% against COVID-19 infection, 96% against COVID-19 hospitalization, and 98% against COVID-19 death.
“This research provides reassuring evidence of the high effectiveness of the Moderna COVID-19 vaccine in preventing infection, hospitalization, and death from COVID-19,” said Katia Bruxvoort, PhD, an adjunct investigator with the Kaiser Permanente Southern California Department of Research & Evaluation. “One of the important aspects of this study was that it included more than 700,000 adults who were racially and ethnically diverse and had a broad range of underlying conditions including chronic diseases, immunocompromising conditions, and autoimmune conditions.”
This study evaluated the 5-month effectiveness of the Moderna COVID-19 mRNA vaccine as part of a 5-year observational study within Kaiser Permanente, an integrated health care organization with 4.7 million members in Southern California.
The study included 352,878 recipients of 2 doses of Moderna COVID-19 vaccine matched to 352,878 unvaccinated individuals by age, sex, race, and ethnicity. Vaccinated individuals received 2 doses of Moderna COVID-19 vaccine from December 18, 2020, to March 31, 2021. Individuals in both groups were followed until June 30, 2021.
- During follow-up, COVID-19 infections occurred among 289 vaccinated patients and 1,144 unvaccinated patients. Vaccine effectiveness against COVID-19 infection was 87%.
- COVID-19 hospitalization occurred among 13 vaccinated and 182 unvaccinated patients, and COVID-19 in-hospital deaths occurred among 1 vaccinated and 25 unvaccinated patients. Vaccine effectiveness against COVID-19 hospitalization was 96%, and vaccine effectiveness against COVID-19 in-hospital deaths was 98%.
- Vaccine effectiveness against COVID-19 infection remained high across age, sex, racial, and ethnic subgroups, with results ranging from 83% to 92%.
- Vaccine effectiveness was higher against symptomatic COVID-19 (88%) than asymptomatic COVID-19 (73%).
- From March to June 2021, there were 5,619 SARS-CoV-2 positive specimens that were successfully sequenced. The most prevalent variants were alpha (42%), epsilon (18%), delta (12%), and gamma (9%), with delta increasing to 54% of variants by June 2021.
“This study adds evidence of real-world Moderna COVID-19 vaccine effectiveness, particularly among the general population,” said Hung Fu Tseng, PhD, a researcher with the Kaiser Permanente Southern California Department of Research & Evaluation and the senior author of the study. “Additionally, our follow-up on these fully vaccinated patients occurred through June 2021, a period that overlapped with the emergence of the delta variant in the United States. Long-term follow-up is ongoing to further evaluate the durability of protection.”
Reference: “Real-world effectiveness of the mRNA-1273 vaccine against COVID-19: Interim results from a prospective observational cohort study” by Katia J. Bruxvoort, Lina S. Sy, Lei Qian, Bradley K. Ackerson, Yi Luo, Gina S. Lee, Yun Tian, Ana Florea, Harpreet S. Takhar, Julia E. Tubert, Carla A. Talarico and Hung Fu Tseng, 25 November 2021, The Lancet Regional Health – Americas.