A new Health Alert Notice from CDC provides updated guidance for health care professional to interpret Zika test results for women who live in, or frequently travel to areas with a CDC Zika travel notice. CDC's Zika testing guidance for pregnant women relies, in part on a test to detect Zika antibodies or proteins that the body makes to fight Zika infections. However, new data indicate that Zika virus infection may result in Zika antibodies staying in the body for months after infection for some people. Results of these tests therefore may not be able to determine whether women were infected prior to or after becoming pregnant. For health care professionals evaluating women without symptoms who had potential Zika exposure, especially women who live in or travel on a daily or weekly basis to areas with CDC Zika travel notices, CDC recommends the following guidance. Use of these tests may be helpful, but may not always be conclusive, in determining how recent the infection is. The guidance recommends screening pregnant women for risk of Zika exposure and symptoms of Zika, and testing pregnant women promptly, using nucleic acid testing, if they develop symptoms at any point during pregnancy of if their sexual partner tests positive for Zika virus infection. Consider NAT testing at least once during each trimester of pregnancy to detect evidence of Zika virus, unless a previous test has been positive. Consider testing specimens obtained during amniocentesis to detect evidence of Zika virus if amniocentesis is performed for other reasons. In addition, CDC recommends counseling all pregnant women each trimester about the limitations of Zika testing. "Our guidance today is part of our continued effort to share data for public health action as quickly as possible," said Henry Walke, MD, incident manager of CDC's Zika response efforts. "As we learn more about the limitations of antibody testing, we continue to update our guidance to ensure that health care professionals have the latest information for counseling patients who are infected with Zika during pregnancy."