“The suggestion that we need new placebo-controlled trials for updated vaccines is particularly concerning. On its surface, it may sound reasonable, but ethically, it’s dangerous to withhold a vaccine that is known to offer protection just to create a placebo-controlled new trial. And practically, it may be impossible to carry out,” Dr. David Higgins, a pediatrician and preventive medicine specialist at the University of Colorado Anschutz Medical Campus, told HuffPost.