Health officials will start administering the shots for free Friday to students in six schools in and around Alliance, a northeastern Ohio city of 23,000.
Officials suspect the two shared a water bottle at a school picnic last month.
The bacteria cause meningitis, a disease of the brain, or meningococcemia, a blood infection. The germs are spread by saliva through such means as drinking out of someone else's glass or sharing a fork or spoon. Symptoms include high fever, headache, stiff neck, confusion, nausea, vomiting and exhaustion. On Saturday and Sunday, thousands in the Alliance area lined up to get antibiotics, and about 37,000 doses were given. But the pills protect people for only a day or two.