NEW YORK (AP) — The potential scope of the meningitis outbreak that has killed at least five people widened dramatically Thursday as health officials warned that hundreds, perhaps thousands, of patients who got steroid back injections in 23 states could be at risk.

Clinics and medical centers rushed to contact patients who may have received the apparently fungus-contaminated shots. And the Food and Drug Administration urged doctors not to use any products at all from the Massachusetts pharmacy that supplied the suspect steroid solution.