A year ago, the mosquito-borne Zika virus was only beginning to reveal itself as a threat to pregnant women and their unborn babies.
Since then, U.S. officials have issued 60 travel alerts along with guidance for athletes and tourists traveling to the Olympics in Rio. They have also deployed more than 1,000 experts to Puerto Rico and elsewhere, tested more than 147,000 lab specimens, initiated 25 major studies and issued more than 230 scientific publications.
And the work is not done, said Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention.