ATHENS — Thirty-three residents and three staff members of a nursing home in Asvestochori, Thessaloniki, have been infected with coronavirus, head of the novel coronavirus committee at the Health Ministry Sotiris Tsiodras said on Wednesday.

The nursing home was placed under a seven-day lockdown later in the day, by health authorities, who said that all people testing positive are being transferred to hospitals in Thessaloniki, said Civil Protection Secretary General Vassilis Papageorgiou, who accompanied Tsiodras and other officials to the facility.

Tsiodras, who had flown urgently to Asvestochori, said the infection spread from a staff member who contracted the virus at a concert in Halkidiki, a popular vacation region of Macedonia. Most of the 36 people infected at the facility have no symptoms, and the few who have were transferred to hospitals of Thessaloniki.

Measures will be introduced at the facility after recommendations by the National Public Health Organization (EODY).

"We have a great epidemic at this nursing home, which was observing all measures diligently, as no guests were allowed," Tsiodras said. "Unfortunately the source was a staff member who was infected in Halkidiki, at least as preliminary sampling shows."

As the epidemiologist pointed out, the case shows that "the virus can cross from an area where there is no danger – young people having fun on an island, or at a holiday place – to a nursing home, a very sensitive unit with elderly people."

Tsiodras said that he saw and greeted all residents at the home and noted that most of whom were in a good state of health. "They were happy, thanked me that I came and will patiently wait this out," he responded to a question.

He added that a great percentage of the cases of Attica and Thessaloniki – where concentrations of new infections are highest – had direct contact with visitors who either returned from Halkidiki to Thessaloniki, or from Cycladic Islands to Attica. "The fact it's summer doesn't mean we can stop paying attention. It may be that younger people are in less danger, but older people such as these (here) are a tragic example of what may happen if we are not careful," he pointed out.

According to analyses by the Health Ministry and EODY, Tsiodras said, "nearly 30 percent of newly infected people the last few weeks do not exhibit symptoms, while a great percentage are under 40 years of age. This doesn't mean however they can't pass the infection onto older people."

Asked whether he is concerned that the median age of those infected recently by the novel coronavirus is lower, he replied, "I'm not worried about being in greater danger, what worries me is that they can pass it on more easily to vulnerable groups, as most of the [young people] are asymptomatic."