My strong view is that everyone should vaccinate. Even if a parent believes their children are healthy and could withstand if they contact a contagious virus without significant danger, nevertheless there’s a societal basis and need that everyone should vaccinate in order to protect those that cannot vaccinate. (Not referring to those that choose not to.) And there’s a society benefit of herd immunization preventing the spreading of the virus, which is lost if too many children aren’t vaccinated.
That said, I think some or all of the nine signatories likely stand by their position today.