Covid, Israel gives the fourth dose to the most fragile but experts are divided on the effectiveness

JERUSALEM – After the third coronavirus vaccine will it be the turn of the fourth, fifth and sixth? To get a first answer, if only how effective it can be to vaccinate every four or five months, the world looks once again to Israel, where in two weeks the new (fourth) booster is already given to more than half a million. over 60, as well as several thousand health workers.