Tel Aviv, 2 September 2021 (dpa/MIA) - Israel's Health Ministry announced a record number of cases of Covid-19 on Thursday, with 11,187 new infections in the past day. The spike came a day after children returned to school, with scientists warning this could fuel a further rise in case numbers. The latest figures were the third day in a row that Israel has announced more than 10,000 new cases. However, the number of people who are severely ill has fallen steadily, and is currently half the level it was in January. Scientists continue to emphasize that the Pfizer/BioNTech shot remains effective in preventing severe illness and death. Israel used the jab exclusively in its world-leading vaccination campaign. Per 100,000 people, the number of cases among the unvaccinated is far higher than the number of those who have vaccinated in all age groups. This applies particularly for those who are severely ill above the age of 60. Israel has also started administering third vaccines, since late July, the first country in the world to do so. More than 25 per cent of Israel's population of 9.4 million has already had a booster shot. The decision to roll out the third jabs was based on Health Ministry data which suggested that the vaccine's effectiveness had fallen significantly since the beginning of June. Overall, more than 59 per cent of citizens have been vaccinated twice.