Susanna, 49, revealed she's self-isolating after her son began showing symptoms of coronavirus.
On Monday (March 16), the Prime Minister Boris Johnson said that if one person in a household has symptoms then everyone in the home must self-isolate for 14 days.
Susanna appeared on the show via video call and told Charlotte and Piers Morgan about why she's self-isolating.
She said: "One of the boys, one of the children, has a persistent cough and that came on yesterday.
"Suddenly with these new drastic action measures, that changed yesterday afternoon, it meant if even one member of your household had either the persistent cough or a fever then you would all have to go into self-isolation for 14 days.
"So that means immediately, I thought, 'I can’t go into work and work with you guys for 14 days.'"
She added: "I am in isolation with my family in order to suppress potential infection.
"I have a perfectly normal temperature, as do all of my children. I do not have a cough, I have no symptoms. I’m not feeling fatigued, I feel 100% healthy."
Viewers were gutted to not have Susanna on the show but many were thrilled by Charlotte hosting with Piers.
Much prefer Charlotte with Piers than Susanna, she should stay.
One person said on Twitter: "I much prefer Charlotte in that seat #GMB."
Another wrote: "Much prefer Charlotte with Piers than Susanna, she should stay #gmb."
A third added: "Charlotte showing her presenting credentials today especially with Morgan ranting on, fairplay to her."
However, others weren't keen on Charlotte and wanted Susanna back.
One tweeted: "I see Charlotte is trying her best to impress the producers and keep @susannareid100’s position for good... she’s trying so hard... bless her cotton socks."
Another wrote: "Charlotte Hawkins making a beeline all morning for Susanna Reid’s anchor role at @gmb."
One said: "Charlotte Hawkins instead of Susanna on #GMB today is super difficult to watch. Way out of her depth amidst these conversations."
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