Prevalence and Risk Factors of Infection in the Representative COVID-19 Cohort Munich

Area of Science:

• Epidemiology
• Infectious Disease Research
• Public Health

Background:

• Mild or asymptomatic cases of SARS-CoV-2 (the virus causing COVID-19) make population-based studies essential for accurate pandemic assessment.
• Understanding the true prevalence of SARS-CoV-2 is crucial for effective public health strategies.

Purpose of the Study:

• To determine the seroprevalence of SARS-CoV-2 in the general population of Munich following the initial pandemic wave.
• To identify risk factors and transmission patterns associated with SARS-CoV-2 seropositivity.

Main Methods:

• A representative sample of 2994 households was surveyed, with participants aged 14+ providing blood samples and completing questionnaires.
• SARS-CoV-2 seropositivity was determined using Roche N pan-Ig assay (≥ 0.4218).
• Prevalence was adjusted for sampling design, sensitivity, and specificity; risk factors and transmission were analyzed using generalized linear mixed models and permutation tests.

Main Results:

• SARS-CoV-2 seropositivity was 1.82% (95% CI 1.28-2.37%), substantially exceeding the 0.46% of officially registered PCR-positive cases in Munich.
• Anosmia (loss of smell or taste) was strongly associated with seropositivity (OR 47.4; 95% CI 7.2-307.0).
• Infections demonstrated significant clustering within households, indicating within-household transmission.

Conclusions:

• The study reveals a higher SARS-CoV-2 burden in the Munich population than official figures suggest, with at least one in four household infections identified.
• Findings underscore the underreporting of SARS-CoV-2 cases and highlight the importance of symptom-based risk factors like smell/taste loss.
• Results provide critical data for public health authorities to estimate the true disease burden and inform evidence-based interventions.