A medical worker performs a COVID-19 test in Amorgos, Greece, on June 7, 2020. Medical staff of the National Public Health Organization went to Amorgos and other Aegean islands to conduct COVID-19 diagnostic and antibodies tests for the residents, ahead of the opening to foreign tourists in mid-June. (Xinhua/Marios Lolos)

A medical worker performs a COVID-19 test in Amorgos, Greece, on June 7, 2020. Medical staff of the National Public Health Organization went to Amorgos and other Aegean islands to conduct COVID-19 diagnostic and antibodies tests for the residents, ahead of the opening to foreign tourists in mid-June. (Xinhua/Marios Lolos)

A medical worker performs a COVID-19 test in Amorgos, Greece, on June 7, 2020. Medical staff of the National Public Health Organization went to Amorgos and other Aegean islands to conduct COVID-19 diagnostic and antibodies tests for the residents, ahead of the opening to foreign tourists in mid-June. (Xinhua/Marios Lolos)

A medical worker performs a COVID-19 test in Amorgos, Greece, on June 7, 2020. Medical staff of the National Public Health Organization went to Amorgos and other Aegean islands to conduct COVID-19 diagnostic and antibodies tests for the residents, ahead of the opening to foreign tourists in mid-June. (Xinhua/Marios Lolos)

A medical worker performs a COVID-19 test in Amorgos, Greece, on June 7, 2020. Medical staff of the National Public Health Organization went to Amorgos and other Aegean islands to conduct COVID-19 diagnostic and antibodies tests for the residents, ahead of the opening to foreign tourists in mid-June. (Xinhua/Marios Lolos)