WASHINGTON, D.C. (WPVI) -- The impact of the zika virus has gone beyond those infected with it.
It's causing blood supply problems in some places.
In February, the FDA issued new guidelines urging people to wait 4 weeks before donating blood if you have traveled to a Zika-affected country.
That's caused donations to drop off in some parts of the country.
The Indiana Blood Center says some blood drives shortly after spring break had to defer up to 30-percent of their donors, because they'd been to the Caribbean, or other areas with Zika virus.
The Red Cross nationwide says through April, less than 1 percent of would-be donors were turned away.
But it doesn't know how many donors just didn't come in to donate.
Blood banks urge people to donate before they travel.
Some are also trying to boost supplies by appealing to donors who haven't traveled, or who haven't donated lately.
Zika travel guidelines affect blood donations in U.S