already, vaccine makers are preparing for the possibility that the current shs will to take three to four months. we were at a certain time need a new vaccine against this new variant. reporter: and one early study suggests a previous case of covid may no longer protect against reininfection from omicron. still, dr. anthony fauci was optimistic today. there s every reason to believe that if you get vaccinated and boosted, that you would have at least some degree of cross-protection, very likely against severe disease, even against the omicron variant. reporter: but the delta variant still makes up nearly all new cases in the u.s., especially among the unvaccinated. from the upper midwest to new england, where new hampshire now leads the country in new cases per capita in the last week. here inside the pandemic response lab, the first four out of five omicron cases in new