This week @US_FDA called for confirmed infection (+-symptoms) as a primary or secondary endpoint in #SARSCoV2 #vaccine trials. Last year @rebeccajk13 @Steve_Bellan Rui Wang and Matt HItchings we recently proposed efficient, unbiased approach: academic.oup.com/aje/article/18…
Link to the FDA guidance fda.gov/regulatory-inf…
One subtle point: preventing infection detected serologically (without symptoms) may be a very difficult endpoint for many vaccines.
It may also not be critical -- vaccines should prevent/reduce symptoms and viral shedding, but one can imagine CoV infections that are serologically detectable, but involve almost no symptoms or shedding -- as in CoV rechallenge expts ncbi.nlm.nih.gov/pmc/articles/P… 
From the perspective of individual protection, reduction in symptomatic infection is of greatest interest. From herd perspective, reduction of virologic infection/shedding is of greatest interest. Serologically detected infection is important to remove bias per our paper.
But further thought needed how to get best estimates of likely herd effects from vaccines during trials --serologically detected infection may or may not be the right marker.
