Bi-annual is not necessary, even if immunity wanes within six months due to the seasonal nature of the beast. So at worst we are looking at something like the y

Bi-annual is not necessary, even if immunity wanes within six months due to the seasonal nature of the beast. So at worst we are looking at something like the yearly flu vaccination. And also very probably younger and healthier people will be able to skip that altogether, just as with the flu vaccine.