A lot of those questions are answered and i don't think first trials have to be in anything but mice, who are very similar in relevant organs. Eg. Kids have mo

A lot of those questions are answered and i don't think first trials have to be in anything but mice, who are very similar in relevant organs. Eg. Kids have more flexible immune systems, while adults immune systems react how they know. The older => the more inflexible when it encounters something new. Eg. You are contagious if you have enough particles produced that are transmittable. With omnicron that's ~2 days, symptoms in ~3 days. Eg. Different variables on why some have it severe ( excluding vaccinations). Health conditions and age are the biggest variables, but there are more, less relevant ones, eg. Vitamine D intake ( they have it to seniors in my country). Omicron correctly is so contagious that the "test subjects" is analyzing real data on humans in place where outbreaks happen. This is mostly because it appears to be very light. Also, Corona virus mutates so fast that performing an additional tests could be useless before results can be interpreted.