November 29, 2021

Moderna COVID-19 vaccine effective 5 months after 2nd dose

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.

Contact: Vincent Staupe

Terry Kanarki

PASADENA, Calif. — Kaiser Permanente research in Southern California published Nov. 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.”

The study was funded by Moderna, Inc.

About Kaiser Permanente

Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Founded in 1945, Kaiser Permanente has a mission to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve approximately 12.5 million members in 8 states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal Permanente Medical Group physicians, specialists, and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery, and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education, and the support of community health.