A baby helps make history. The Kenyan child is receiving the new malaria vaccine — the first ever that can wipe out a parasite — as part of a clinical trial. Karel Prinsloo/AP hide caption

itoggle caption Karel Prinsloo/AP

This did not really happen. Cows' heads did not emerge from the bodies of people newly inoculated against smallpox. But fear of the vaccine was so widespread that it prompted British satirist James Gillray to create this spoof in 1802. H. Humphrey/Henry Barton Jacobs Collection, Institute of the History of Medicine, JHU hide caption

itoggle caption H. Humphrey/Henry Barton Jacobs Collection, Institute of the History of Medicine, JHU

Vikram is the first child to wear a Khushi Baby necklace, which will keep track of his immunizations. He's at a vaccine clinic in Rajasthan, India. Ruchit Nagar/Courtesy of Khushi Baby hide caption

itoggle caption Ruchit Nagar/Courtesy of Khushi Baby

Which flu vaccine should you get? That may depend on your age and your general health. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

Proteins and enzymes that will produce antibodies for the experimental Ebola drug ZMapp are developed on the leaves of the nicotiana benthamiana plant, a relative of tobacco. Here, indicator proteins glow under ultraviolet light — a way to assess the success of bacteria spread. Sean Gallup/Getty Images hide caption

itoggle caption Sean Gallup/Getty Images

A health worker administers the malaria vaccine at a clinical trial in Kilifi, Kenya. Joseph Okanga/Reuters /Landov hide caption

itoggle caption Joseph Okanga/Reuters /Landov

Kimberly Delp gives a flu shot to Carleen Matthews at the Homewood Senior Center in Pittsburgh, Pa., last September. Andrew Rush/AP hide caption

itoggle caption Andrew Rush/AP