There are many student insurance plans available for international students in the US.
The International Medical Group (IMG) is an US insurance provider who has two popular student medical insurance plans.
Patriot Exchange plan from IMG is highly popular among the J1 Visa and F1 Visa holders visiting the US. It satisfies most of the requirements of the Universities. The unique feature of this plan is that the J2 or the F2 wanting to buy insurance without the J1 or the F1 being on the plan can continue to buy this plan. This is not available with other student plans. Other plans would want the J1 or the F1 to be the primary insured. This plan however does not cover pregnancy and maternity which can be a downside of the plan.