When the Centers for Disease Control and Prevention lifted its last Zika travel advisory for Miami-Dade County last week, residents and visitors to Miami's popular South Beach neighborhood were relieved. Still, doctors say, pregnant women should continue to take extra precautions. Joe Raedle/Getty Images hide caption
Pregnant women â and those trying to get pregnant â should not travel to places where the Zika virus is circulating. For children, age is a factor. Alessandro Abel/Getty Images/EyeEm hide caption
Puerto Rico resident Michelle Flandez caresses her two-month-old son Inti Perez, diagnosed with microcephaly linked to the mosquito-borne Zika virus. The U.S. Centers for Disease Control and Prevention says the Zika virus continues to impact a small number of pregnant women and their babies in the U.S. Carlos Giusti/AP hide caption
A family member holds twins Eloisa (left) and Eloa, both 8 months old and born with microcephaly, during a Christmas gathering. The mother of the twins, Raquel, who lives in Brazil, said she contracted Zika during her pregnancy. Mario Tama/Getty Images hide caption
Yalieth Gonzalez and her baby Micaela Delgado at the Maternal Infant Studies Center at the University of Puerto Rico. Marisa Penaloza/NPR hide caption
The National Institutes of Health is based in Bethesda, Md., but the vast majority of its research funding flows to universities around the country. NIH/Flickr hide caption
Andie Vaught grasps a stress toy in the shape of a truck as she prepares to have blood drawn as part of a clinical trial for a Zika vaccine at the National Institutes of Health in Bethesda, Md., in November 2016. Allison Shelley/The Washington Post/Getty Images hide caption
From left: A scene from the video of a car crash test; illustration of a mosquito transmitting the Zika virus; a menstrual shed in Nepal. Insurance Institute for Highway Safety/YouTube; BSIP/UIG via Getty Images; Poulomi Basu/Magnum Emergency Fund hide caption
No one is sure why the northeastern part of Brazil has been hit so hard with microcephaly cases. Felipe Dana/AP hide caption
Florida Department of Health workers package a urine test, part of the state's effort to provide free Zika tests to pregnant women. Joe Raedle/Getty Images hide caption
A mother holds her baby, who has microcephaly, in Recife, Brazil. Mario Tama/Getty Images hide caption
Sudanese dockers unload a U.S. aid shipment at Port Sudan on the Red Sea coast on May 5. Ashraf Shazly/AFP/Getty Images hide caption
The Zika virus has been largely spread by mosquitoes, but it can also be spread by sexual intercourse. NIAD/Flickr hide caption