ATHENS — Greek authorities on Friday said they will reimpose tougher lockdown restrictions in greater Athens after a January decline in infection rates was reversed this week.

Most retail stores will close in the capital Saturday, retaining pickup services only, after being allowed to reopen on Jan. 18.

Plans to reopen high schools in Athens Monday have been limited to the first three grades, while older students will remain in online classes, officials from Greece's Health Ministry and Civil Protection Agency said.

The additional restrictions will also be in effect on the eastern Aegean Sea island of Lesbos and in 10 municipal regions around Greece.

Greece registered 941 new coronavirus cases on Friday, of which 17 were identified at the country's entry points, said the National Public Health Organization (EODY). All cases in Greece total 155.678 of which 5.927 relate to travel from abroad and 48.600 to already confirmed infection cases.

Meanwhile, infectious diseases specialist Vana Papaevangelou said that the rapid change in Attica region infections last week after three weeks of an improving set of data "is disturbing".

In a live briefing with ministers and another doctor, both of them members of the Health ministry's coronavirus pandemic committee, she said that the rise in infections in Attica was observed "across the board in all neighborhoods, not just a single metropolitan sector or municipality of Attica."

Numbers also rose, she said, in hospitalized patients in Attica, where plain Covid-19 beds are 43 percent full and ICUs devoted to the disease are 61 pct full.

Greece imposed lockdown measures — that eventually included a nationwide curfew as well as school and store closures — in early November amid a huge spike in cases.

With a population of 10.5 million, Greece has recorded some 15,000 confirmed COVID-19 infections and 5,764 deaths, according to numbers released Friday.

The number of people globally who have received at least one dose of the coronavirus vaccine is over 80 million, member of the Health Ministry's coronavirus committee Gkikas Magiorkinis said on Friday.

During a live briefing with ministers and another committee member, also an infectious disease specialist, Magiorkinis said that in Europe 30 million people have been diagnosed as having been infected and 690,000 have died of Covid-19.

He added that the global death rate did not drop as of September, but recent signs show it may be falling. In Europe, the rate of new diagnoses appears to be going down to around 200,000 new cases per day, Magiorkinis said.

Alternate Health Minister Vassilis Kontozamanis said during a question-and-answer period with the press that coronavirus vaccines "cannot be sold in the black market in Greece as the distribution and its storage is controlled by the state." He did point out however that there are online attempts to market so-called vaccines.