PESHAWAR, Pakistan (AP) — Suspected militants shot and killed a police officer guarding a team of polio workers in northwestern Pakistan on Tuesday, the latest in a series of attacks on vaccine teams in the country. The attack took place in the Matta area of Khyber Pakhtunkhwa province, once a stronghold of the Pakistani Taliban, a day after Pakistan launched a weeklong nationwide vaccination campaign to immunize 45 million children. Local police official Javed Khan said a team of female polio