A protester dressed as a clown holds an umbrella over a Swiss police officer on a motorbike during a May Day demonstration in Zurich, Switzerland on May 1, 2017. (Photo by Arnd Wiegmann/Reuters)

A reveller walks through the streets in the early hours during traditional May Day celebrations in Oxford, Britain, May 1, 2015. (Photo by Dylan Martinez/Reuters)

Students from the University of St Andrews jump into The North Sea, as a good luck tradition before exams start on the East Sands in St Andrews, Fife, Scotland on May 1, 2018. (Photo by Derek Allan/Alamy Live News)

Nazi dictator Adolf Hitler greets supporters at a May Day gathering in the Olympic Stadium, Berlin. (Photo by Keystone). 1st May 1938

A model rehearses with a fabric face mask on, designed by Zhou Li for her Autumn/Winter 2020 collection show, during China Fashion Week in Beijing, following the novel coronavirus disease (COVID-19) outbreak, China on May 3, 2020. (Photo by Tingshu Wang/Reuters)

Riot police wear face masks, as a precautionary measure against the COVID-19 coronavirus, allow a women to cross a cordon after a protest by pro-democracy demonstrators at a shopping mall in Hong Kong on May 9, 2020. (Photo by Isaac Lawrence/AFP Photo)

Health authority workers sanitise the rural community of Teocelo, Veracruz, Mexico on May 12, 2020 – in the hope of preventing the spread of COVID-19 infections. (Photo by Hector Adolfo Quintanar Perez/ZUMA Wire/Rex Features/Shutterstock)

Members of the Israeli Mermaids Community bathe in the sea with a mermaid tails at the beachfront in Bat Yam, near Tel Aviv, Israel, Saturday, May 23, 2020. Members of the Israeli mermaid community gathered at the beachfront to mark the beginning of the bathing season. (Photo by Oded Balilty/AP Photo)