The U.S. government has spent more than $10 billion creating vaccines to protect against COVID-19 but so far little encouraging Americans to take them.

Public health officials say that’s a mistake.

“This needed to happen yesterday. It’s like watching a train wreck happen,” said Daniel Salmon, director of the Institute for Vaccine Safety at Johns Hopkins Bloomberg School of Public Health.

Now, even before any vaccines are approved, is the time to start telling America straight-up what to expect, more than a dozen public health and medical experts told USA TODAY.

That includes warning that a COVID-19 vaccine likely won’t be 100% effective, getting it will make a substantial number of people “feel like crud” for a day or two,and two shots will be required, not just one.