Add Yahoo as a preferred source to see more of our stories on Google. US regulators will not review Moderna's request to license a new, potentially more effective flu shot - even though the US Food and Drug Administration (FDA) previously gave the green light to the project - in a decision that could have implications for all new and updated vaccines in the US.

Vaccines use 'dead, inactivated or killed virus' that cannot cause illness, doctor says NEWYou can now listen to Fox News articles.