Projecting Omicron scenarios in the US while tracking population-level immunity.

Area of Science:

• Epidemiology
• Public Health
• Mathematical Modeling

Background:

• The COVID-19 pandemic saw multiple transmission waves driven by policy changes, behavior shifts, and new SARS-CoV-2 variants.
• Accurate risk assessments were crucial for healthcare capacity, mitigation strategies, and public communication.

Purpose of the Study:

• To introduce a COVID-19 transmission and vaccination model for rapid and reliable projections during variant emergence.
• To assess population-level immunity and simulate the impact of interventions like booster vaccinations.

Main Methods:

• Developed a transmission and vaccination model for COVID-19.
• Tracked population immunity using reduction in susceptibility due to prior infections and vaccinations.
• Simulated the impact of increased booster vaccination rates on mortality.

Main Results:

• The model provided accurate short-term national projections for COVID-19 hospitalizations and mortality peaks.
• As of October 1, 2022, US population susceptibility to BA.4/BA.5 variants was reduced by 36.52%, with immunity from infections, primary series, and boosters.
• A five-fold increase in boosting could have vaccinated 70% of those over 65 and averted 25,000 deaths during the BA.4/BA.5 surge.

Conclusions:

• The model offers a robust framework for tracking population immunity against evolving COVID-19 variants and vaccines.
• It enables effective simulation of future scenarios for novel variant emergence and mitigation strategies.
• Enhanced booster vaccination coverage is critical for reducing severe outcomes and mortality.