[Clinical courses and costs for hospitalizations of potentially immunocompromised COVID-19 patients in Germany].

Background:  Patients at increased risk of inadequate immune response to COVID-19 vaccinations due to their underlying disease or therapy are potentially vulnerable to severe COVID-19 courses. The aim is to assess the population size, clinical courses and hospitalization costs of these patients in Germany.

Methods:  This retrospective cohort study is based on extrapolations of a representative sample of statutory health insurance (SHI) claims data from 2020. Clinical COVID-19 courses, hospitalization costs and durations are compared between the insured group at increased risk for inadequate immune response to COVID-19 vaccinations (risk group) and the insured group without this risk.

Results:  There are approximately 1.82 million SHI-insured individuals in the risk group, of whom an estimated 240 000 insured individuals do not develop a humoral immune response after 3 COVID-19 vaccinations. The risk group shows higher proportions with COVID-19 (relative risk [RR] 1.21; 95 % confidence interval [95 % CI] 1.20-1.23), hospitalizations for COVID-19 (RR 3.40; 95 % CI 3.33-3.48), hospitalizations for COVID-19 with intensive care treatment (RR 1.36; 95 % CI 1.30-1.42), and mortality (RR 5.14; 95 % CI 4.97-5.33) compared with the group without risk. In addition, hospitalizations in the risk group are on average 18 % longer (15.36 days vs. 13.00 days) and 19 % more expensive (12 371 € vs. 10 410 €). Expected hospitalization costs in the risk group are four times greater than in the group without risk (4115 € vs. 1017 €).

Conclusions:  The risk group is vulnerable to COVID-19 and requires additional resources in the German hospital sector. This results in a need for further protective measures. Further studies are needed to evaluate the impact of different viral variants, active and passive immunizations, and therapies on clinical COVID-19 courses and their costs.