The U.S. government is launching research into a possible vaccine for the mosquito-borne Zika virus, which has been connected to birth defects in Latin America. Meanwhile, the Centers for Diseases Control and Prevention have expanded an alert to pregnant women considering travel to the Caribbean and Latin America.
Dr. Anthony Fauci of the National Institutes of Health Tuesday warned that the vaccine's development would "not happen overnight."
But there are other vaccines in various stages of development for the same family of viruses—dengue, West Nile and chikungunya—that offer a pattern for creating something similar to combat Zika, said Fauci, who directs the NIH's National Institute of Allergy and Infectious Diseases.
Vaccine development and approval typically takes years. There is no cure for the disease.
Also on Tuesday, the CDC issued a travel alert for the U.S. Virgin Islands and the Dominican Republic. In the past two weeks, the agency has issued travel alerts for more than 20 areas. The agency recommended that pregnant women avoid nonessential travel to all regions under alert.
Countries on the CDC warning list are: Barbados, Bolivia, Brazil, Colombia, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname and Venezuela. Cape Verde, off the coast of western Africa, and Samoa in the South Pacific are also included in the travel alert.
The virus has been spreading for the past year. Health officials in Brazil estimate more than 1 million cases have been diagnosed since the start of the outbreak. Zika virus has been linked to birth defects in 3,500 infants born with microcephaly, a condition where the head is significantly smaller than normal.
Reported U.S. cases of Zika have recently been found in Arkansas, Florida, Hawaii, Illinois and Texas. Health officials say those cases have all been related to travel to Central and South America.
CDC spokeswoman Candice Hoffman said public health teams are working to improve diagnostic testing for Zika virus, and resources are being pooled from across the agency to respond.
Only four states have the capability to test for Zika. That requires most samples of suspected cases to be shipped to CDC laboratories for diagnosis.
Asked about the probability of a widespread Zika outbreak in the U.S., Hoffman said the CDC could not predict an epidemic, but added that recent history has shown how tropical diseases spread.
“It is possible, as a result of imported cases, that we may see some limited, local transmission of Zika virus in some parts of the United States, similar to what has occurred with chikungunya and dengue viruses,” Hoffman wrote in an email.
The CDC recently also offered guidance to doctors on testing newborns for Zika. Healthcare providers should ask all pregnant women about recent travel to an affected area, the CDC advised, and evaluate any potentially at-risk patients for signs of disease transmission.
Doctors treating pregnant women who test positive for the Zika virus are advised to administer ultrasounds every three to four weeks to monitor fetal growth.
The Associated Press contributed to this report.