Where does this come from, and can I check it?

A trial involving hundreds of thousands of schoolchildren reported results in April. The figure is taken from Smithsonian Institution, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a history fact?

Yes. It sits on the History shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Salk's polio vaccine was declared effective in 1955

A trial involving hundreds of thousands of schoolchildren reported results in April Jonas Salk's killed virus vaccine was tested in a trial that began in 1954 and involved some 1.8 million children across the United States. On 12 April 1955 the results were announced as safe and effective, and a national immunisation campaign began within days. Later oral vaccines by Albert Sabin made mass dosing simpler. It sits in Mondo's history collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Smithsonian Institution

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Tags: polio, vaccines, public-health

Salk's polio vaccine was declared effective in 1955: the short answers

Where does this come from, and can I check it?: A trial involving hundreds of thousands of schoolchildren reported results in April. The figure is taken from Smithsonian Institution, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a history fact?: Yes. It sits on the History shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.