 The third dose of Pfizer-BioNTech's COVID-19 vaccine was 86 percent effective in people over 60. An Israeli healthcare provider said on Wednesday, citing initial results from a study of thousands of members. Israel began administering third Pfizer doses last month to confront a surge in local infections driven by the Delta variant. Some 1.1 million eligible Israelis, people over 50, healthcare workers and others have received their third dose. United States and several European countries are expected to begin offering boosters to the elderly and people with weak immune systems and some are considering whether to make a third dose available for more widely. Nonetheless, Israelis health officials worry that cases will continue to mount given that another 1.1 million Israelis around 11 percent of the population are unvaccinated. Severe cases have also continued to climb, mostly among the unvaccinated.