No vaccinations are required for visitors to Israel.
Israel is an entirely western country with an advanced level of health care, diagnosis and medicine that is the envy of much of the world and on a par with the best of North America and Western Europe. Almost everyone in the health care field - from pharmacists to physicians to nurses - understands and speaks good English.
As for all international travel, visitors to Israel should have travel insurance that covers them in case of illness or hospitalization. Pharmacies in Israel are to be found everywhere and are very well stocked with drug store items and all the over-the-counter medicines you may need.
Should you become ill during your trip, your hotel front desk can arrange for a doctor to visit you in your room, and prescribe medication if necessary. If you are staying with friends or family, they will be able to refer you to their local clinic. In case of serious illness or injury, the emergency rooms at Israel's hospitals are western standard and you will receive the finest medical care.

