Aims of the Study
1. Collect stool, blood samples and temperature measurements from 256 healthy adult participants aged 8-35 years in Germany before and after vaccination for COVID-19.
2. Determine microbiome community structure and activity (using metagenomics and metatranscriptomics), and the host immune response (body temperature, fecal transcriptional activity and serum antibodies) for all participants before and after vaccination.

Endpoints
1. Profile the intestinal microbiota and host immune response in healthy adults over the course of COVID-19 vaccination.
a. Determine whether the baseline microbiota (average longitudinal composition prior to vaccination) is associated with the strength of the subsequent immune response to vaccination (fever response, transcription of inflammatory markers in feces if present, serum antibody levels).
b. Determine whether there are microbiota shifts associated with vaccination (i.e., consistent changes in abundance or transcriptional activity following the vaccine compared to baseline).
c. Determine whether there are microbiota shifts associated with fever (i.e., changes in abundance or transcriptional activity associated with increased body temperature).