Austria's health minister has said he is stepping down because of exhaustion.
Rudolf Anschober, 60, was appointed in January 2020 and led the country's health response to the pandemic.
"In the worst health crisis in decades the republic needs a health minister who is 100% fit," he told reporters. "That is not currently me."
He said his 15 months in office had "felt like 15 years". Chancellor Sebastian Kurz said his minister had "sacrificed himself for our country".
Mr Anschober's replacement in the coalition government has been named as Wolfgang Mückstein, a trained doctor and fellow Green Party member.
A former teacher, Mr Anschober told reporters on Tuesday: "I'm overworked and exhausted."
He explained that he had been suffering from a number of health complaints including high blood pressure, circulation and blood sugar issues.
"In a pandemic, no-one is free of mistakes," he said, defending the government's record. "I believe that despite mistakes, a lot was done right in this country."
Austrian President Alexander Van der Bellen thanked Mr Anschober "in the name of the Republic and also personally for your untiring work in this infinitely difficult and stressful time of the pandemic".
Chancellor Kurz, meanwhile, said the minister's decision to resign showed the impact of the pandemic not just on the individual, but also on a person in authority "who is on duty day and night and must make decisions".
Rudi Anschober of the Greens was one of Austria's most popular politicians. He had become known for his long patient explanations about the pandemic.
But in recent months, he found himself increasingly at odds with Chancellor Sebastian Kurz's conservatives, the senior partner in Austria's coalition government. Mr Anschober was in favour of stricter lockdown measures to deal with rising infections. The Conservatives were keen to open up rapidly.
In his parting remarks, Mr Anschober said that the tensions from outside the government and within had left him feeling very alone. Last November, Mr Anschober was given police protection after receiving death threats.
His farewell was marked by a characteristic openness about illness. "No-one needs to be ashamed of disease," he said. "It is important that we get rid of taboos."
During his time in office, Austria became one of the first countries in Western Europe to implement a mask mandate. A local lockdown is currently in place in the capital Vienna, amid high infection numbers.
Mr Anschober is not the first European official to resign during the pandemic due to exhaustion.
In March last year, Dutch Health Minister Bruno Bruins stepped down after collapsing during a parliamentary debate on coronavirus.