But after sending out a tweet Saturday morning that he’d gotten his COVID-19 vaccine, the eight-foot-tall flightless yellow canary has raised the ire of people from Ted Cruz to Arizona state senator Wendy Rogers.

Within hours, Ted Cruz was labeling the tweet as “Government propaganda…for your 5 year old.” The next morning, others, including Rogers, piled on.

While some of the ire against Big Bird is likely due to the politicization of vaccines, especially as a fight looms over President Joe Biden’s vaccine mandate, some of the protests are likely because Big Bird cited CNN’s Erica Hill in his tweet. (The Sesame Street icon was part of a collaboration between Sesame Street and CNN, which had a town hall centered on vaccines featuring the show’s characters Saturday morning.)

Cruz later poked fun at the backlash he faced for his tweets, saying, “Libs are really triggered by Big Bird.”

The furor comes days after the Centers for Disease Control and Prevention approved the use of COVID-19 shots for children between the ages of 5 and 11. Through the pandemic, there have been more than 8,300 hospitalizations of kids ages 5 to 11, about a third requiring intensive care, according to government data. The CDC has recorded at least 94 deaths in that age group.

More health care and Big Pharma coverage from Fortune:

• ‘Vax’ is Oxford English Dictionary’s word of the year
• With a vaccine mandate looming, these apps help businesses check which employees got vaxxed
• Novavax COVID-19 vaccine’s long-delayed global rollout will start in Indonesia, fueling hope for more equitable distribution
• 100 million Indians have skipped their second vaccine dose, leaving the country vulnerable to a third COVID wave
• A COVID scare trapped 33,000 visitors inside Shanghai Disneyland in a ‘surreal’ scene