calling for a fourth dose a month ago. israel already offers the fourth shot for high-risk groups, health care workers, anyone over 60. should the u.s. do the same? >> well, i think right now it's probably too late because by the time you get that through and get the fda and cdc to sign off on it and by the time we get an immune response and vaccinated health care providers and that's the group i suggested that we tried for it will be three or four weeks from now and by then possibly the omicron wave will have subsided and we'll be having to worry about the next variant. so i think at this point, the best thing to do is to -- let's see what the data from israel shows. the reason i was concerned about not giving a second booster was based on information that we got from imperial college london showing that within a couple of months after the boost, you got a decline in effectiveness down to 30% to 40% so the idea is you boost, get a big bump in virus neutralizing antibodies and