Shadow Health Secretary Jonathan Ashworth has tested positive for COVID-19 and is self-isolating.
The leading Labour MP said he will be “out of action for a bit” after announcing he had tested positive on Friday morning.
He did not say whether his family or members of his staff have also tested positive for COVID or are self-isolating.
The MP used his situation to warn that although “huge strides have been made” there is “still a lot of virus circulating”.
Mr Ashworth added: “So get your jab and booster, do routine lateral flow tests, wear masks in crowded places.”
He also urged the government to “fix sick pay and ventilation”.
The shadow health secretary has previously pushed the government to invest in better ventilation for businesses, public spaces and schools.
Speaking in the Commons last month, he said: “Better ventilation has been proven, time and again, to reduce the transmission of COVID.
“In addition, it brings other health benefits.”
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Mr Ashworth joins a host of other politicians who have contracted coronavirus, including Boris Johnson and Sir Keir Starmer.
The current rules in England mean anybody who tests positive must self-isolate for 10 days.
People must also self-isolate and get a PCR test if they have a high temperature, a new, continuous cough or a loss or change to their sense of smell or taste.
Since 16 August, people who are fully vaccinated have not had to self-isolate if a household member tests positive or has symptoms.