Estimating the distribution of COVID-19-susceptible, -recovered, and -vaccinated individuals in Germany up to April 2022

Abstract

After having affected the population for two years, the COVID-19 pandemic has reached a phase where a considerable number of people in Germany have been either infected with a SARS-CoV-2 variant, vaccinated, or both. Yet the full extent to which the population has been in contact with either virus or vaccine remains elusive, particularly on a regional level, because (a) infection counts suffer from under-reporting, and (b) the overlap between the vaccinated and recovered subpopulations is unknown. Since previous infection, vaccination, or especially a combination of both reduce the risk of severe disease, a high share of individuals with SARS-CoV-2 immunity lowers the probability of severe outbreaks that could potentially overburden the public health system once again, given that emerging variants do not escape this reduction in susceptibility. Here, we estimate the share of immunologically naïve individuals by age group for each of the 16 German federal states by integrating an infectious disease model based on weekly incidences of SARS-CoV-2 infections in the national surveillance system and vaccine uptake, as well as assumptions regarding under-ascertainment. We estimate a median share of 7.0% of individuals in the German population have neither been in contact with vaccine nor any variant as of March 31, 2022 (quartile range [3.6%– 9.8%]). For the adult population at higher risk of severe disease, this figure is reduced to 3.5% [1.3%–5.5%] for ages 18–59 and 4.3% [2.7%–5.8%] for ages 60 and above. However, estimates vary between German states mostly due to heterogeneous vaccine uptake. Excluding Omicron infections from the analysis, 16.1% [14.0%–17.8%] of the population in Germany, across all ages, are estimated to be immunologically naïve, highlighting the large impact the Omicron wave had until the beginning of spring in 2022.

Safety and effectiveness of vaccines against COVID-19 in children aged 5–11 years: a systematic review and meta-analysis

“…Because the history of previous infections of included children was rarely reported and data analyses of remaining studies primarily included children who did not have a previous known SARS-CoV-2 infection, it remains unclear whether results are generalisable to children with previous infections. Given that the high seroprevalence in this age group, 66 the additional benefit of vaccination in children aged 5–11-years cannot be reliably assessed with the underlying data of this systematic review. However, investigations of older age groups (≥16 years) suggest a preferable protective effect for individuals being both previously infected and vaccinated, 67 , 68 which was also suggested by data provided from Khan and colleagues 32 for children aged 5–11 years.…”

Modeling the impact of the Omicron infection wave in Germany

“…Note that the model was calibrated up to January 1, 2022. Retrospectively, approximately 14.8 million Omicron infections have been reported up to April 1, 2022 [16, 17], which is approximately 10% below our median expectation, hence rather accurate considering we expected our model to overestimate the peak size by a maximum of 10%. Similarly, the observed incidence peaks in mid February (peak: 191k daily new cases) and mid March (peak: 230k daily new cases) [16], as well as the time series of new hospitalizations and cases in ICU care, respectively, lied within expectation.…”

Estimating the share of SARS-CoV-2-immunologically naïve individuals in Germany up to June 2022

“…Data availability statement. The code and results of the simulations can be obtained from Zenodo [39].…”