AS India rushes to vaccinate its people against the coronavirus, medical workers often have to trek to perilous heights and across treacherous terrain to reach those in remote areas. In the northern region of Lidderwat, more than 100 km (60 miles) from the capital of India-administered Kashmir, medical teams have had to trek more than six hours on foot and ponies to reach nomadic and shepherd tribes in the mountains. On a recent morning, Reuters tagged along with a team of over a dozen health workers carrying medical kits and equipment including oxygen cylinders atop ponies and on foot to…