Bialik, who is best known for her role in "The Big Bang Theory," made the announcement on Instagram Sunday and said the virus is "no joke."
She said exhaustion has been the most difficult symptom.
"Why did I ever go out? Why did I think everything was fine ever?" Bialik said.
Bialik has asthma, making her immunocompromised.
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A spokesperson for the game show host said that she's fully vaccinated.
Bialik is hoping the virus passes quickly and that her body knows what to do to heal.