the third dose of an mrna and second dose of the j&j. it's natural for the antibodies to go down, but there are things that aren't easily measurable, to look at the level of the memory response, both memory b-cells that make antibody and t-cells that give you durable protection. if that goes out for a longer period of time, that will determine how often you need to get boosted. i don't think one can project that right now until we get the data. >> are there any signs of the booster shot or that third dose having diminishing protection? we know some people got that third dose, more than five months ago. should they be worried? >> well, i shouldn't say they should be worried. i would say what they need to do