The head of the American Federation of Teachers told NBC's "Meet the Press" on Sunday that the union's leadership should consider implementing a vaccine mandate for teachers in schools.

Why it matters: The move would mark a policy reversal from last October, when the union allowed vaccinations on a voluntary basis. AFT President Randi Weingarten called the Delta variant of the virus "alarming" and voiced concern for children who cannot yet be vaccinated.

What they're saying: "[V]accines are the single most important way of dealing with COVID, we've always dealt with or — since 1850 — we've dealt with vaccines in schools, it's not a new thing to have immunizations in schools," Weingarten said.

• Weingarten noted that "circumstances have changed" since the union's original policy was implemented in October.
• "It weighs really heavily on me that kids under 12 can't get vaccinated," she added.

The big picture: The American Federation of Teachers is the second largest teachers union in the country and leadership will convene this week to consider a formal policy change, Weingarten said.

• Becky Pringle, president of the National Education Association, the nation’s largest teachers union, told the New York Times last week that vaccine mandates should be negotiated at the local level.
• NIAID director Anthony Fauci told Meet the Press in a separate segment on Sunday that children who aren't be vaccinated should be surrounded by vaccinated adults in schools.