JERUSALEM, (Reuters) –Israel has extended its offer for a fourth dose of COVID-19 vaccine to seniors in care facilities. Health Minister Nitzan Horovitz said Friday that this was due to their vulnerability and high level of exposure to infection.

On Thursday, the Health Ministry’s director-general, Nachman Ash, approved https://reut.rs/3EK1R3n fourth doses for people with weakened immune systems and the administering of those shots began on Friday.

An Israeli hospital administered fourth shots to a test group https://reut.rs/3mKSzhq of health workers on Monday, in what it called the firstmajor study into whether a second round of boosters will helpcontend with the Omicron coronavirus variant.

The results are expected to be available within the next two weeks. The Health Ministry panel that analyzed the situation recommended that Israel provide a fourth shot with the vaccine. Pfizer (NYSE:) BioNTech offers medical personnel and seniors with compromised immunity systems, as well as BioNTech to doctors.

Israel became the country that launched initial vaccinations the fastest, and was also the one to start a booster program after it noticed how immunity had declined over the years. The policies of Israel regarding boosters are being closely observed by the United States and other countries, who also consider when to provide additional doses.