Top 5 Takeaways

1. Vaccine Effectiveness (VE) Variability: VE against COVID-19–associated emergency department/urgent care visits was 24% after 1 Janssen dose, 54% after 2 Janssen doses, 79% after 1 Janssen/1 mRNA dose, and 83% after 3 mRNA doses.
2. Hospitalization Protection: VE against COVID-19–associated hospitalization was 31% after 1 Janssen dose, 67% after 2 Janssen doses, 78% after 1 Janssen/1 mRNA dose, and 90% after 3 mRNA doses.
3. Booster Recommendations: Adults who received a primary Janssen vaccine dose should preferentially receive a heterologous mRNA vaccine booster dose ≥2 months later.
4. Study Scope: The study examined 80,287 emergency department/urgent care visits and 25,244 hospitalizations across 10 states during December 16, 2021–March 7, 2022.
5. Durability of Protection: Further investigation is warranted to assess the durability of protection afforded by different booster strategies.

Original Article Author and Citation

Corresponding Author

Namrata Prasad, riz9@cdc.gov

Suggested Citation

Natarajan K, Prasad N, Dascomb K, et al. Effectiveness of Homologous and Heterologous COVID-19 Booster Doses Following 1 Ad.26.COV2.S (Janssen [Johnson & Johnson]) Vaccine Dose Against COVID-19–Associated Emergency Department and Urgent Care Encounters and Hospitalizations Among Adults — VISION Network, 10 States, December 2021–March 2022. MMWR Morb Mortal Wkly Rep 2022;71:495–502. DOI: http://dx.doi.org/10.15585/mmwr.mm7113e2

Summary

This study assessed the real-world effectiveness of different COVID-19 booster strategies following a primary Janssen vaccine dose during the Omicron variant predominance. The study found that VE against COVID-19–associated emergency department/urgent care visits and hospitalizations was significantly higher for those who received any booster dose compared to a single Janssen dose. The highest VE was observed in those who received 3 mRNA doses.

Methods

The VISION Network study included 80,287 emergency department/urgent care visits and 25,244 hospitalizations across 10 states. VE was estimated using a test-negative design and multivariable logistic regression models, adjusting for various factors including age, geographic area, and comorbidities. Patients were categorized based on their vaccination status and excluded if they did not meet specific criteria related to timing and type of vaccination.

Discussion

The study found that all booster strategies provided higher protection against COVID-19–associated medical encounters compared to a single Janssen dose. A heterologous booster strategy (1 Janssen/1 mRNA dose) offered higher protection than 2 Janssen doses and was comparable to 3 mRNA doses for emergency department/urgent care visits. However, 3 mRNA doses provided the highest protection against hospitalizations.

Conclusion

The findings underscore the importance of receiving recommended COVID-19 booster doses to prevent moderate to severe COVID-19 during Omicron variant predominance. Adults who received a primary Janssen vaccine dose should preferentially receive a heterologous mRNA vaccine booster dose ≥2 months later.

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