Both/and, but is it more there are signs of diminishing returns on additional doses or is there a concern that the next booster for the next booster we may need it to be variant specific and so we need to hold out for that? yes. you hit the nail on the head. the only thing more complicated than the immuno system is the evolution of this crazy virus. so we don t know if there is going to be a variant that s around the corner that is going to be so what we call antigenically distinct from the current set of variants that it will completely escape the immune system s ability to respond. if that s s the case, we are going to need a different vaccination and that won t be the same as a booster. it will probably be a complementary vaccine. so lots of reasons to carefully chart the molecular evolution of the virus in the population, emerging variants and keep our tabs closely on what people are doing from an immuno logic