[lamontcg]

I had viral pericarditis after a cold one time, but it appeared about 2 months after I had recovered.

That's pretty common with autoimmune conditions triggered by IgG autoimmunity response.

But we understand autoimmunity in response to individual exposure to antigens pretty well and while 1-7 days is probably too short to see a lot of responses, over 3 months is highly unlikely. There can be a long tail of certain individuals having autoimmune responses up until 2 years later, but in a population study if you capture nearly all the responses after 3 months. If you don't see anything 3 months later then there's no hidden long-term effects waiting to happen years later.

And there's nothing fundamentally unique about the mRNA vaccinations that would cause anything different. It is just a dose of mRNA that looks like any other mRNA payload from a virus which is wrapped in a lipid package that fuses with the lipids in your cell wall (and we understand the allergy to PEG that some people have against the lipid nanoparticle itself). All of the 200 years of understanding of vaccinations and hundreds of years of autoimmune conditions subsequent to viruses still apply to the mRNA vaccines. The "no we don't understand anything about these new things and the clock starts from zero" is just a fantastically ignorant argument based on no understanding of what the vaccines are built from and what vaccines and viruses are and how they interact with the immune system.

So both of you are kind of wrong. 7 days is too short, but 90 days is all you need.

[elcritch]

Thanks, good to know about pericarditis. I’m not well versed on that or myocarditis and in particular the IgG or T-Cell response mechanism. Though the little I’ve read seems to indicate myocarditis is still primarily due to an acute immune response, but can re-occur or turn into a more autoimmune condition (chromic myocarditis or perhaps pericarditis).

That said I would normally give the benefit of doubt that the authors of a paper in the Lancet are more well versed on myocarditis and it’s behavior. It looks like they do adjust all their comparisons to odds ‘per 100,000 person-days’. If done properly that would adjust from an event basis to per-time basis or rate which could account for long tail reactions.

Using 90 days would risk including non-vaccine related myocarditis risks as well, which is perhaps why the lancet paper uses the time rate basis. If someone got a normal cold after a month and got pericarditis that'd skew the results as an example. Though I was disappointed to not see statistical analysis or comparison to normal occurrence rates of myocarditis without vaccine exposure, etc. though I didn’t thoroughly check their references, etc.