Top 5 Takeaways

1. Higher Incidence in Unvaccinated: Unvaccinated individuals had a significantly higher incidence of SARS-CoV-2 infection (30.1 per 1,000) compared to fully vaccinated individuals (8.7 per 1,000).
2. Increased Risk of Severe Outcomes: Unvaccinated persons were more than twice as likely to require emergency department care or hospitalization compared to vaccinated persons.
3. Mortality Rates: The crude mortality rate was sevenfold higher among unvaccinated patients (0.43 per 1,000) compared to fully vaccinated patients (0.06 per 1,000).
4. Vaccine Effectiveness: The data support the effectiveness of COVID-19 vaccines in preventing severe illness, hospitalizations, and deaths, especially during the Delta variant surge.
5. Public Health Recommendation: The findings reinforce CDC recommendations for full COVID-19 vaccination, including booster doses, for all eligible individuals to protect against severe outcomes.

Original Article Author and Citation

Corresponding Author

Eduardo Azziz-Baumgartner, eha9@cdc.gov

Suggested Citation

Naleway AL, Groom HC, Crawford PM, et al. Incidence of SARS-CoV-2 Infection, Emergency Department Visits, and Hospitalizations Because of COVID-19 Among Persons Aged ≥12 Years, by COVID-19 Vaccination Status — Oregon and Washington, July 4–September 25, 2021. MMWR Morb Mortal Wkly Rep 2021;70:1608–1612. DOI: http://dx.doi.org/10.15585/mmwr.mm7046a4

Summary

This study assessed the incidence of SARS-CoV-2 infection, emergency department visits, and hospitalizations among individuals aged ≥12 years in Oregon and Washington from July 4 to September 25, 2021, by vaccination status. The findings indicated that unvaccinated individuals had a significantly higher incidence of infection and were more likely to require emergency care or hospitalization compared to vaccinated individuals. The study supports the effectiveness of COVID-19 vaccines in reducing severe outcomes and reinforces CDC recommendations for vaccination.

Methods

The study was conducted within Kaiser Permanente Northwest, an integrated health care system in Oregon and Washington. It included individuals aged ≥12 years with continuous health plan enrollment during the surveillance period. SARS-CoV-2 infections were identified using nucleic acid amplification tests (NAATs). Vaccination status was determined from electronic medical records and state immunization information systems. Incidence rates were calculated and stratified by demographic factors, and Poisson regression models were used to estimate incidence rate ratios (IRRs).

Discussion

The study found that the incidence of SARS-CoV-2 infection was significantly higher among unvaccinated individuals across all demographic groups. Unvaccinated individuals were also more likely to require emergency care or hospitalization and had a higher mortality rate. These findings are consistent with other studies showing the protective effects of COVID-19 vaccination against severe illness, especially during the Delta variant surge. The study highlights the importance of vaccination in preventing severe outcomes and supports CDC recommendations for full vaccination.

Conclusion

The data from this study underscore the critical role of COVID-19 vaccination in reducing the incidence of infection, emergency department visits, hospitalizations, and deaths. The findings support CDC recommendations for full vaccination, including booster doses, to protect individuals and communities against severe COVID-19 outcomes, particularly during periods of variant surges.

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