Israel will continue to offer a fourth Covid-19 vaccine shot despite preliminary findings that it is not enough to prevent Omicron infections, a senior health official said on Tuesday, predicting contagions stoked by the variant will wane in a week.

The fastest country to roll out vaccinations a year ago, Israel last month started offering a fourth shot - also known as a second booster - to its most vulnerable and high-risk groups.

A preliminary study published by...