ATHENS – Adding to fears it's not fully safe, the United Kingdom's AstraZeneca COVID-19 vaccine was the cause of at least two of three blood clots in Greece, an initial report from the National Organization for Medicines (EOF) found.

A 35-year-old man from Ierapetra on Crete was hospitalized after suffering two blood clots only a few days after being inoculated but was said to be out of danger, Kathimerini reported of the incidents.

A 44-year-old woman was in serious condition at the island’s General University Hospital of Iraklio with a rare but severe type of blood clot (vaccine-induced thrombotic thrombocytopenia, or VITT) the paper said.

Officials are also investigating what happened to a 47-year-old woman at the same clinic who became paralyzed after receiving the vaccine that many Greeks are shunning out of apprehension, frantically trying to switch to other versions.

Greece has been accelerating its campaign called Eleftheria (Freedom) but won't be able by summer to reach the magic mark of vaccinating at least 70 percent of the population of 10.7 million – some 7.49 million people – that's needed to bring herd immunity, the standard set by health authorities.

So far little more than 13 percent have been inoculated, the program held back by a cumbersome European Union distribution program that failed to deliver enough doses on time, but millions more are coming this spring.

Greece is trying to create oases of immunity on islands and the New Democracy government said all residents of 85 islands would be fully protected by the end of June in anticipation of more tourists arriving who are also free of the virus.'

But that is seeing staggered results, said Kathimerini, with 19 islands in a so-called Blue Freedom program that will use the single-shot Johnson & Johnson vaccine from the United States.

The platform for vaccination appointments was divided into two groups of dates – May 17- 22 and May 23-30. In the first group, bookings almost reached full capacity, exceeding 90 percent but Kephalonia, Limnos and Samos didn't hit the mark.

The paper said that the islands of Salamina, Paros, Rhodes, Mykonos, Corfu, Naxos, Aegina and Thasos had 100 percent appointment rates, followed closely by Chios, Santorini and Lefkada.

The Secretary General for Primary Healthcare Marios Themistokleous appealed for people to book appointments but the government hasn't made being vaccinated mandatory despite the health crisis still killing dozens daily.