Participating in this observational study will not benefit the participants and healthy volunteers. The study will provide information about the influence of leukocyte DNA methylation as well as the gut and respiratory microbiota on host defense mechanisms during CAP. The knowledge obtained can potentially benefit CAP patients in the future by providing alternative immune modulating treatment options that modify the host response. The burden and risks for patients participating in the ELDER-BIOME study is minimal. The investigators will take 90ml of blood, 4 rectal swabs and 2 nasopharyngeal swabs divided over two time-points (day of presentation and day 28 post presentation). Healthy volunteers will be subjected to one blood draw (70 ml) and 2 rectal - and 2 nasopharyngeal swabs at one time-point.