A child looks back at Kiev zoo in Kiev, Ukraine, May 23, 2020. The zoo reopened to the public on May 23 with a controlled visitor flow as a response to counter the COVID-19 pandemic. All people in and out are required to wear face masks and receive temperatures checking. (Photo by Sergey Starostenko/Xinhua)

Visitors look at an alpaca at Kiev zoo in Kiev, Ukraine, May 23, 2020. The zoo reopened to the public on May 23 with a controlled visitor flow as a response to counter the COVID-19 pandemic. All people in and out are required to wear face masks and receive temperatures checking. (Photo by Sergey Starostenko/Xinhua)

A staff member checks body temperature of a child at Kiev zoo in Kiev, Ukraine, May 23, 2020. The zoo reopened to the public on May 23 with a controlled visitor flow as a response to counter the COVID-19 pandemic. All people in and out are required to wear face masks and receive temperatures checking. (Photo by Sergey Starostenko/Xinhua)

Visitors look at an alpaca at Kiev zoo in Kiev, Ukraine, May 23, 2020. The zoo reopened to the public on May 23 with a controlled visitor flow as a response to counter the COVID-19 pandemic. All people in and out are required to wear face masks and receive temperatures checking. (Photo by Sergey Starostenko/Xinhua)