Model based estimation of the SARS-CoV-2 immunization level in austria and consequences for herd immunity effects

Area of Science:

• Epidemiology
• Infectious Disease Modeling
• Public Health

Background:

• Global herd immunity for COVID-19 remains a challenge in 2021.
• Vaccine availability and emerging SARS-CoV-2 variants hinder widespread immunity.
• Assessing population immunization levels is crucial for understanding epidemic spread.

Purpose of the Study:

• To estimate the immunization level of the Austrian population against SARS-CoV-2.
• To discuss the potential impact of this immunization on herd immunity effects.
• To provide data for decision-makers regarding non-pharmaceutical interventions.

Main Methods:

• Utilized a calibrated agent-based simulation model to replicate the COVID-19 pandemic in Austria.
• Extracted immunization data from synthetic individual-based simulation outputs.
• Compared simulation findings with a classic SIR-model for validation.

Main Results:

• As of February 2021, an estimated 7.5% of the Austrian population was affected by SARS-CoV-2 infection.
• This level of natural immunization resulted in a 15% reduction in the effective reproduction number.
• A 20% reduction in the prevalence peak was observed compared to a fully susceptible population.

Conclusions:

• Natural immunization in Austria has a measurable impact on reducing SARS-CoV-2 transmission.
• Regular re-computation of immunization levels, including vaccination effects, is vital for ongoing analysis.
• Model-based insights support evidence-based decisions on public health interventions.