Depending on your destination, you maybe required to be vaccinated. Generally, most countries now only require a negative PCR test. Airlines in JFk or, for that matter, any other airport will allow you to board their planes with a negative PCR test. Some destination, like I mentioned above, will admit you if you are fully vaccinated without the need for a PCR test and airlines will follow this rule.
I don't think so
You at least have.to wear a mask.
Not domestic but international.
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