Republican politician Ted Cruz was one to criticise the Sesame Street star after Big Bird shared a message in support of vaccinating children.
The children's television fixture, who has always been six years old, tweeted a message over the weekend to announce he had received the jab himself.
"I got the COVID-19 vaccine today! My wing is feeling a little sore, but it'll give my body an extra protective boost that keeps me and others healthy," he miraculously tweeted with his large feathered fingers.
Big Bird added that CNN journalist Erica Hill "even said I've been getting vaccines since I was a little bird. I had no idea!"
The tweet came after the Pfizer vaccine was approved for use in children aged 5 and up in the United States.
It was met with a furious response by controversial Republican Ted Cruz, who described the message as "Government propaganda".
Other figures on the right-wing of US politics also weighed in, including FOX News host Lisa Boothe who said it was "brainwashing children who are not at risk from COVID".
Although the majority of children experience a mild or asymptomatic infection with Covid-19, large scale infection of children can lead to even rare outcomes such as severe illness or the rare complication multi-inflammatory syndrome becoming more frequently seen.
Cruz was widely criticised for his comment, including from Parkland school massacre survivor David Hogg.
Hogg wrote: "Ted Cruz is doing the job of our enemies by spreading more disinformation that's killed over 200,000 Americans this year.
"I can not believe an actual sitting senator would tweet this."
Hogg also recalled Cruz's decision to skip out of Texas during a deadly winter storm with a withering response online.
"At least it's acceptable for birds to fly south for the winter - unlike some senators who left millions of their constituents to f****** die in the cold."
Walter Shaub, former head of the Office of Government Ethics, reminded Cruz that he had the jab.
"You are vaccinated," he told the senator.
"Liberals are weird," he tweeted.
"They don't care about open borders. Or rising inflation. Or schools covering up sexual assaults. Or the disaster of Afghanistan. Or tyrannical Dems violating medical privacy and freedom.
"But criticise Big Bird? And they lose their s***."