Costumed revelers pose in front of the Chapell bridge on the opening day of the carnival in Lucerne, Switzerland, 20 February 20​20. The carnival takes place in Lucerne from 20 to 25 February 2020. (Photo by Alexandra Wey/EPA/EFE)

People wear masks to help guard against the Coronavirus in downtown Tehran, Iran, Sunday, February 23, 2020. On Sunday Iran's health ministry raised the death toll from the new virus to 8 people in the country, amid concerns that clusters there, as well as in Italy and South Korea, could signal a serious new stage in its global spread. (Photo by Ebrahim Noroozi/AP Photo)

U.S. President Donald Trump holds news conference on the coronavirus outbreak at the White House in Washington, U.S., February 26, 2020. (Photo by Carlos Barria/Reuters)

An Indian lift operator stands inside a dedicated lift for people suspected to be infected with the new corona virus at the Government Gandhi Hospital in Hyderabad, India, Monday, March 2, 2020. Coronavirus has spread to more than 60 countries, and more than 3,000 people have died from the COVID-19 illness it causes. (Photo by Mahesh Kumar A./AP Photo)

Protesters wear gas masks in the front of the Romanian Environment Ministry in Bucharest March 4, 2019, to demand better air. Dozens of people holding placards reading “Our children don't breath air anymore” gather in the front of the Environment Ministry to ask for better breathable air in Bucharest. (Photo by Daniel Mihailescu/AFP Photo)

A man, wearing a protective mask following an outbreak of the coronavirus disease (COVID-19), walks in Tokyo, Japan on March 17, 2020. (Photo by Edgard Garrido/Reuters)

Paramedics wearing protective suits amid fears of coronavirus outbreak check on a man who collapsed outside a clinic in Jakarta, Indonesia, Thursday, March 26, 2020. It's not immediately clear what caused the man to collapse. The U.S. Embassy in Indonesia has ordered the departure of employees' family members under the age of 21 from its missions in the country where new COVID-19 patients have surged in the past week with high fatality. (Photo by Muchlis Akbar/AP Photo)

A lady wearing a mask feeds pigeons in St James' Park, as the spread of the coronavirus disease (COVID-19) continues, London, Britain, April 5, 2020. (Photo by Henry Nicholls/Reuters)