The agency overseeing the nation’s health plans on Friday issued a policy to expand the range of people eligible for a four-in-one shot meant to prevent infections caused by the contagious Zika virus.
As of next year, travelers to Zika outbreak areas can be prescribed the shot, along with shots for common colds and flu. But before then, the Centers for Disease Control and Prevention and the World Health Organization are expected to set guidelines for the dosage.
Currently, only about 100,000 people in the United States have been confirmed to have been infected with Zika, and there is little evidence that the vaccine works.
The 4-in-1 shot isn’t an effective preventive against Zika. It targets a subset of the same class of viruses associated with head lice and rubella and is considered a “baby flu shot” for older people.
Still, it’s seen as an important part of the battle against Zika, which has spread to over 40 countries and territories in the Americas and is rapidly growing in Asia and Africa.
Using a same-group model of disease transmission, a CDC official in August predicted that about 60 million people would be infected by the end of the year. Those figures are conservative estimates for the United States.
“Preventing Zika is not going to be easy,” said Dr. Ann Tenborg, a CDC deputy director. “Even with the current immune system, you might not have the protection to completely prevent the virus if you were to get infected with Zika.”
The hope is that with more U.S. citizens able to be vaccinated against the virus, less travel would need to be taken to areas with Zika outbreaks, allowing those areas to slow the spread of the disease.
Zika infections in pregnant women can cause microcephaly in their newborns, which means babies may be born with brains not fully developed. Some cases have also been linked to other severe fetal brain damage. The vaccines developed to date are not expected to have those effects.
The 3-in-1 shot is considered a more convenient option because it is taken four times a year and does not require two separate injections. It also has been used for decades in those who are immune to rubella, or who have already had the flu shot.
The birth-control shots, provided for free by most health plans, don’t protect against other pathogens, such as influenza or dengue. Also, women who are pregnant are not advised to take them.
Current health guidelines recommend giving the 4-in-1 vaccine every three months, with four doses spaced a few weeks apart.
In a statement, the American College of Obstetricians and Gynecologists said it was “encouraged that these studies suggest early exposure to the 4-in-1 vaccine could be beneficial.” But, the organization added, more research is needed to confirm that.