Clinical Scorecard: Assessing Community Immunity and the Effects of COVID-19 Vaccination in Washington and Oregon

At a Glance

Key Highlights

• Vaccination reduced total hospitalizations by 74% from primary doses and an additional 15% from boosters.
• Vaccination effectiveness was highest during the Alpha variant wave, averting 90% of hospitalizations.
• Vaccinating individuals aged 18–49 significantly reduced hospitalizations among those aged 65+.

Guideline-Based Recommendations

Diagnosis

• Severe COVID-19 defined as any diagnosed case resulting in hospitalization and/or death per state health departments.

Management

• Implement mRNA-based primary vaccination and booster doses to reduce hospitalizations.
• Prioritize vaccination in older adults (65+) and extend vaccination to younger adults (18–49) to maximize community protection.

Monitoring & Follow-up

• Use age- and region-structured surveillance data including weekly hospitalizations to monitor vaccine impact.
• Incorporate serosurveillance data for validation of immunity estimates.

Risks

• Waning immunity over time and emergence of immune-evading variants may reduce vaccine effectiveness.
• Nonpharmaceutical interventions and changing epidemic dynamics influence transmission and hospitalization rates.

Patient & Prescribing Data

General population of Washington and Oregon, stratified by age groups

Primary vaccination averts majority of hospitalizations; booster doses provide additional protection; vaccinating younger adults indirectly protects older adults.

Clinical Best Practices

• Use compartmental epidemic models incorporating vaccine and infection-induced immunity to guide public health decisions.
• Consider hybrid immunity and waning effects when assessing population-level protection.
• Rapid vaccination rollout and inclusion of younger age groups enhance overall hospitalization prevention.

References

• Centers for Disease Control and Prevention serosurveillance data