Israel tests fourth dose of Covid-19 vaccine to battle Omicron variant

Israel became the first country to officially administer a fourth dose of the vaccine, known as a second booster, in a trial to determine immune response

Professor Jacov Lavee receives a fourth dose of Pfizer-BioNTech COVID-19 vaccine, at Sheba Medical Center in Ramat Gan, Israel, Monday, Dec.  27, 2021.  Israel began trials of a fourth dose of coronavirus vaccine on Monday with 150 medical personnel who received a booster dose in August in what is believed to be the first study of its kind.  (AP Photo / Tsafrir Abayov)
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