Shadow education secretary Angela Rayner has confirmed she has quarantined herself after developing Covid-19 symptoms.
The Labour deputy leader candidate is following medical advice and is self-isolating after developing symptoms that have "gradually got worse".
It follows the news that prime minister Boris Johnson has tested positive for coronavirus, but pledged to continue leading the national fight against the outbreak from No 10.
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Anyone showing signs of coronavirus, which include a temperature and a persistent dry cough, have been instructed to self-isolate for seven days, and everyone living in their household should do the same for a two-week period.
Ms Rayner posted on Twitter: "I am now in self-isolation as I have the symptoms of coronavirus – they started last night and have gradually got worse.
"I will be a bit quieter than usual but will still be keeping in touch with people as best as I can."
The timing of the Ashton-under-Lyne MP's isolation means she will be permitted to leave her house by the time the Labour leadership and deputy leadership results are announced on 4 April.
She is the favourite to be crowned the party's new number two, succeeding Tom Watson, who stood down at the last election.
Ms Rayner urged her followers to "keep safe" and reiterated the government message to "stay home, save lives".