German Chancellor Angela Merkel has gone into quarantine after being informed a doctor who administered a vaccine to her has tested positive for coronavirus.

Her spokesman said she was informed about the doctor's test shortly after holding a news conference on Sunday announcing new measures to curb the spread of the virus.

Steffen Seibert said Merkel had received a precautionary vaccine Friday against pneumococcal infection.

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He said the 65-year-old will undergo "regular tests" in the coming days and continue with her work from home for the time being.

Merkel had earlier expressed her gratitude to Germans who were following rules on social distancing, saying it was important to remain at least 1.5 metres apart to reduce the likelihood of infection.

"I know that it means sacrifice," she said, citing the economic and social costs of the lockdown. "I'm moved by the fact that so many are abiding by these rules.

"This way we show care for older and sick people because the virus is most dangerous to them. In short - we are saving lives with this."

She added: "My life has also fundamentally changed and now consists largely of phone calls and video conferences."

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The development illustrated how even world leaders are not free from the risk of infection.

"With a certain distance the risk of infections is reduced almost to zero," Merkel told reporters. "Whether you are half a metre apart or 1.5 metres apart makes a huge difference."

Shortly afterwards, she was informed her doctor had tested positive for Covid-19.