People line up to get COVID-19 vaccination at a walk-in vaccination center in University of Malta, Msida, Malta, on July 19, 2021. Malta opened walk-in COVID-19 vaccination clinics for people without appointments on Monday. More mobile vaccination clinics are expected to be opened in the coming days to meet people's demand. (Photos: Xinhua)

People line up to get COVID-19 vaccination in Mosta, Malta, on July 19, 2021. Malta opened walk-in COVID-19 vaccination clinics for people without appointments on Monday. More mobile vaccination clinics are expected to be opened in the coming days to meet people's demand.

People line up to get COVID-19 vaccination in Mosta, Malta, on July 19, 2021. Malta opened walk-in COVID-19 vaccination clinics for people without appointments on Monday. More mobile vaccination clinics are expected to be opened in the coming days to meet people's demand.

People line up to get COVID-19 vaccination at a walk-in vaccination center in University of Malta, Msida, Malta, on July 19, 2021. Malta opened walk-in COVID-19 vaccination clinics for people without appointments on Monday. More mobile vaccination clinics are expected to be opened in the coming days to meet people's demand.

People line up to get COVID-19 vaccination in Mosta, Malta, on July 19, 2021. Malta opened walk-in COVID-19 vaccination clinics for people without appointments on Monday. More mobile vaccination clinics are expected to be opened in the coming days to meet people's demand.

People line up to get COVID-19 vaccination at a walk-in vaccination center in University of Malta, Msida, Malta, on July 19, 2021. Malta opened walk-in COVID-19 vaccination clinics for people without appointments on Monday. More mobile vaccination clinics are expected to be opened in the coming days to meet people's demand.