Top 5 Takeaways

1. Lower Vaccine Effectiveness: The effectiveness of mRNA vaccines against COVID-19-associated hospitalization was lower among immunocompromised adults (77%) compared to immunocompetent adults (90%).
2. Variation Among Subgroups: Vaccine effectiveness varied significantly among different immunocompromised subgroups, ranging from 59% in organ or stem cell transplant recipients to 81% in those with rheumatologic or inflammatory disorders.
3. Recommendations for Immunocompromised: Immunocompromised individuals should receive three doses of mRNA vaccines and a booster, adhere to nonpharmaceutical interventions, and be monitored closely if infected.
4. Data Source: The study used data from the VISION Network, which includes integrated medical, laboratory, and vaccination records from seven U.S. health care systems and research centers.
5. Consistency Across Variables: The lower vaccine effectiveness among immunocompromised patients persisted regardless of mRNA vaccine product, age group, and timing of hospitalization relative to the Delta variant predominance.

Original Article Author and Citation

Corresponding Author

Peter J. Embi, pembi@regenstrief.org

Suggested Citation

Embi PJ, Levy ME, Naleway AL, et al. Effectiveness of 2-Dose Vaccination with mRNA COVID-19 Vaccines Against COVID-19–Associated Hospitalizations Among Immunocompromised Adults — Nine States, January–September 2021. MMWR Morb Mortal Wkly Rep 2021;70:1553–1559. DOI: http://dx.doi.org/10.15585/mmwr.mm7044e3

Summary

This study evaluated the effectiveness of two doses of mRNA COVID-19 vaccines in preventing COVID-19-associated hospitalizations among immunocompromised adults compared to immunocompetent adults. Data from the VISION Network covering hospitalizations in nine states from January to September 2021 were analyzed. The study found that vaccine effectiveness was lower among immunocompromised adults (77%) compared to immunocompetent adults (90%). The effectiveness varied among different subgroups of immunocompromised individuals.

Methods

The study used a test-negative design to compare the odds of a positive SARS-CoV-2 test result between fully vaccinated and unvaccinated patients. Data were collected from 187 hospitals in nine states, focusing on adults aged 18 years and older with COVID-19-like illness. Vaccination status was verified through electronic health records and state immunization registries. The analysis adjusted for factors such as age, geographic region, calendar time, and local virus circulation.

Discussion

The findings indicate that while mRNA COVID-19 vaccines are effective in preventing hospitalizations among immunocompromised individuals, the level of protection is significantly lower compared to immunocompetent individuals. This supports the CDC’s recommendation for a third vaccine dose and a booster for immunocompromised individuals. The study also highlights the need for additional preventive measures and close monitoring of infected immunocompromised patients.

Conclusion

Immunocompromised individuals benefit from mRNA COVID-19 vaccines but require additional doses and preventive measures to achieve better protection. Further research is needed to understand the variations in vaccine effectiveness among different immunocompromised subgroups and to explore ways to enhance vaccine efficacy in these populations.

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