Muzaffarabad, Pakistan ? Health authorities Saturday launched a two-week campaign to immunize 800,000 children in divided Kashmir to prevent infectious disease from thriving in the crowded and sometimes squalid tent camps for earthquake survivors.

Meanwhile, Pakistan and India opened a third crossing through their disputed Kashmir frontier as part of limited cooperation between the nuclear rivals since the Oct. 8 quake. But it involved only a ceremonial swap of aid as with the previous two openings – with no crossings by Kashmiri residents.

Also Saturday, calm returned to a makeshift refugee camp in Muzaffarabad a day after police used bamboo canes and rifle butts to break up a march by survivors protesting eviction from the public park where they had been living.

Pakistani police said they had no immediate plans to move the camp residents.

U.N. and Pakistani health officials spearheading the immunization drive in Pakistan’s portion of Kashmir are racing to protect children before the region’s savage winter strikes, starting in the most remote towns hit by the quake and working their way toward larger hubs.