A new cluster of five Zika infections around Miami Beach has led the U.S. Centers for Disease Control and Prevention to issue a warning for pregnant women to avoid the area of transmission.

In addition to the travel advisory that warns pregnant women to stay away from the part of Miami Beach where Zika transmission is ongoing, the U.S. Centers for Disease Control and Prevention (CDC) advised pregnant women and their partners to consider avoiding nonessential travel to all of Miami-Dade County if they are concerned about the virus.

CDC director Dr. Tom Frieden told reporters today they wanted to err on the side of caution.

“We'll always err on the side of providing more information to the public," Frieden told reporters. "That's why we've highlighted we are quite concerned about these two areas where we know there has been a spread of Zika through local mosquitoes."

Miami Beach has certain characteristics that may make it more difficult for public health officials to fight the virus' spread, Frieden said today. He said aerial spraying cannot be conducted because of Miami Beach's high-rise buildings. In addition, the area's large crowds mean more people are likely to be exposed, and few in the tourist-heavy beach community are likely to follow recommendations to wear long sleeves and pants, Frieden said.

“The inability to use aerial spraying means we’ll be reduced to ground-based technology," he said.

Florida Governor Rick Scott announced the new site of Zika transmission this morning.

"We believe we have a new area where local transmission is occurring in Miami Beach," the governor said.

Scott announced that state officials have identified the infections, which they believe have been transmitted by local mosquitoes, in Miami Beach. The five people infected -- three men and two women -- include two Florida residents and three visitors from Texas, New York and Taiwan, respectively. In total, 36 people have been infected with Zika virus in the first local outbreak in the continental U.S.

Scott said the new area is under 1.5 square miles in size and that mosquito control officials were spraying in an effort to reduce the population of the Aedes aegypti mosquito that spreads the Zika virus.

Previously, health officials believed local Zika virus transmission was limited to the Wynwood neighborhood in north Miami. That area, which is less than a square mile, has been subject to intense mosquito control and public health efforts to reduce infections.

Scott and Florida Surgeon General Dr. Celeste Philip explained to reporters today why they had not announced the second transmission site yesterday, following multiple media reports of a second outbreak location.

“I want to assure everyone that if we I.D. additional areas of local transmission we will tell the local public immediately,” Philip told reporters today. Philip said there were a number of investigations in progress, but that there have been no other suspected areas of local transmission, aside from the two identified areas.

She said the investigation into the new cases concluded this morning.

Scott called for assistance from the federal government, including guidance for working with the Federal Emergency Management Agency (FEMA), and asked the U.S. Centers of Disease Control and Prevention for additional lab support and 5,000 more tests for the Zika virus.