Mr Newsom has not tested positive. Both children have mild symptoms and will quarantine.
“The governor’s children tested positive for Covid-19,” spokesperson Erin Mellon said in a statement on Friday night. “The governor, the first partner, and the other two children have since tested negative. The family is following all Covid protocols.”
She added: “The Newsoms continue to support masking for unvaccinated individuals indoors to stop the spread and advocate for vaccinations as the most effective way to end this pandemic.”
All four of the Newsom children are under the age of 12 and therefore are not eligible for vaccination per the current CDC guidelines. The two children, who have not been named to protect their privacy, tested positive on Thursday.
Politico reports the governor’s office said that it does not appear that the children were exposed to the virus at school or at any campaign events prior to Mr Newsom successfully fending off an unsuccessful recall attempt.
Governor Newsom received the single-shot Johnson & Johnson vaccine in April and has not received a booster shot.
The Newsoms’ experience is similar to that of many families with young unvaccinated children who are still susceptible to Covid-19 – and this is not the first time that their family has been affected by the virus.
They entered into a 14-day isolation period in November after the children were in contact with a California Highway Patrol officer who had tested positive. In the same month, one of the children was quarantined after a classmate also tested positive for the virus.
Both of the elder children, aged 10 and 11, were pulled out of summer camp back in July when it was discovered that other campers were maskless despite state policies mandating masks.
Neither the governor, nor first partner Jennifer Siebel Newsom, are known to have contracted Covid-19 since the beginning of the pandemic.
California currently has one of the lowest Covid-19 transmission rates in the nation and the lowest case rate.
More than 82 per cent of the population over 12 have had at least one dose of a coronavirus vaccine and strict local mask and vaccination mandates have been credited with keeping cases down even during the spread of the Delta variant.