February 21, 2022

Study looks at Moderna COVID-19 vaccine effectiveness

Kaiser Permanente study shows 3 doses of Moderna COVID-19 vaccine highly effective against hospitalization from omicron or delta.

Contact: Elizabeth Schainbaum

Terry Kanakri

PASADENA, Calif. — New Kaiser Permanente research published in Nature Medicine shows that while Moderna COVID-19 vaccine protection is strong against coronavirus infection by the delta variant, it is not as strong against infection from the omicron variant.

Three doses of the Moderna COVID-19 vaccine were highly effective against hospitalization caused by infection from either the omicron or delta variant.

This study was conducted within the racially and ethnically diverse membership of Kaiser Permanente in Southern California using specimens collected between December 6 and December 31, 2021.

It included 26,683 patients who tested positive for COVID-19, 16% of whom had delta infections and 84% of whom had omicron infections, and more than 67,000 individuals who tested negative as a comparison group. Specimens were primarily collected using nasopharyngeal or oropharyngeal swabs for people with COVID-19 symptoms and saliva for people who did not have symptoms.

  • Two doses of the Moderna COVID-19 vaccine were 44% effective against omicron infection within 3 months after vaccination, and effectiveness quickly declined thereafter.
  • Three doses of the Moderna COVID-19 vaccine within 2 months of vaccination were 94% effective against delta infection and 72% effective against omicron infection.
  • For people who had compromised immune systems, 3-dose effectiveness against omicron infection was lower at 29%.
  • The 3-dose effectiveness against hospitalization with delta or with omicron was above 99%.

“Our results suggest that third doses may be needed sooner than 6 months after the second dose of the Moderna COVID-19 vaccine to protect against omicron infection,” said Hung Fu Tseng, PhD, a researcher with the Kaiser Permanente Southern California Department of Research & Evaluation and a faculty member of Kaiser Permanente Bernard J. Tyson School of Medicine, both located in Pasadena, Calif. “And that 3 doses may be inadequate to protect people who are immunocompromised from omicron infection.”

He added: “Reassuringly, 3 doses provide strong protection against COVID-19 hospitalization due to either the omicron or delta variant.”

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 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.