The University of California, Berkeley, is requiring people on campus who are not protected against the flu to wear masks.
"Masks are required during flu season if not vaccinated for flu," the school’s website says under its mask requirements page.
The guidelines also strongly recommend people wear masks indoors regardless of COVID-19 vaccination status, and that "masks are optional for everyone" if they are outdoors.
The requirements for people who have not gotten the flu shot set off a firestorm of criticisms on social media.
"At Berkeley anyone who isn’t vaccinated for the flu must wear a mask, by executive order from the university president. This is where we are," author Jennifer Sey tweeted Monday.
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Berkeley’s communication’s team did not immediately respond to Fox News Digital’s request for comment Wednesday.
The news comes as other universities across the country have continued enforcing indoor mask requirements over the coronavirus in settings such as classrooms, including at George Washington University, NYU, University of Hawaii and others.
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In Philadelphia, the public school district announced earlier this month that all students must mask up for the first 10 days of school. Students and staff at the district's pre-K program will be required to wear a mask for the entire school year.