People hold candles to mourn the victims of COVID-19 during an event in Vienna, Austria, Dec. 19, 2021. A commemorative event was held here on Sunday to mourn the 13,000 lives lost to COVID-19 in Austria. (Photo: Xinhua)

People hold candles to mourn the victims of COVID-19 during an event in Vienna, Austria, Dec. 19, 2021. A commemorative event was held here on Sunday to mourn the 13,000 lives lost to COVID-19 in Austria. (Photo: Xinhua)

People hold candles to mourn the victims of COVID-19 during an event in Vienna, Austria, Dec. 19, 2021. A commemorative event was held here on Sunday to mourn the 13,000 lives lost to COVID-19 in Austria. (Photo: Xinhua)

People hold candles to mourn the victims of COVID-19 during an event in Vienna, Austria, Dec. 19, 2021. A commemorative event was held here on Sunday to mourn the 13,000 lives lost to COVID-19 in Austria. (Photo: Xinhua)

A girl holds a candle to mourn the victims of COVID-19 during an event in Vienna, Austria, Dec. 19, 2021. A commemorative event was held here on Sunday to mourn the 13,000 lives lost to COVID-19 in Austria. (Photo: Xinhua)