Citizens are seen on a street in Vilnius, Lithuania, Sept. 13, 2021. Lithuania started to use the COVID-19 vaccine certificate on Monday. People without certificate will not be allowed to enter certain public recreation places. (Xinhua/Xue Dongmei)

A staff member checks the COVID-19 certificate of a man at the entrance of a shopping mall in Vilnius, Lithuania, Sept. 13, 2021. Lithuania started to use the COVID-19 vaccine certificate on Monday. People without certificate will not be allowed to enter certain public recreation places. (Xinhua/Xue Dongmei)

Citizens are seen outside a shopping mall in Vilnius, Lithuania, Sept. 13, 2021. Lithuania started to use the COVID-19 vaccine certificate on Monday. People without certificate will not be allowed to enter certain public recreation places. (Xinhua/Xue Dongmei)

Citizens are seen on a bus in Vilnius, Lithuania, Sept. 13, 2021. Lithuania started to use the COVID-19 vaccine certificate on Monday. People without certificate will not be allowed to enter certain public recreation places. (Xinhua/Xue Dongmei)

Citizens get off a bus in Vilnius, Lithuania, Sept. 13, 2021. Lithuania started to use the COVID-19 vaccine certificate on Monday. People without certificate will not be allowed to enter certain public recreation places. (Xinhua/Xue Dongmei)