Greece will offer a second COVID-19 booster dose for people aged 60 and above, at least four months after the previous shot, Greek health officials said on Tuesday.

“The relative platform will open on April 7th ,” Marios Themistocleous, Greek health ministry’s secretary general in charge of vaccinations told a televised briefing.

Another health ministry official said that the decision to offer a fourth round of mRNA shot came as infections in the country were still high and the booster dose has shown it was effective in preventing COVID-related deaths.

Health authorities reported 18,988 COVID-19 cases and 70 related deaths on Tuesday, bringing the country’s total number of infections to 3.11 million. Some 27,816 have so far died from the COVID-19 disease.