Israel, which has led the world in vaccinations and strategies, is now administering a second booster to those 60 and over.
It was the first country to start administering “booster shots”, to people vaccinated at least five months previously.
Due to the highly transmissible omicron variant, the government decided over the weekend to approve the fourth dose.
The second booster shot will be given to people 60+ and also those with weakened immune systems, but discussions are already underway about offering the fourth shot to the general population.
Other Nations are watching the results as they debate adding a second booster to the fight.