DUBAI, United Arab Emirates (AP) — A recent spate of infections from a frequently deadly Middle East virus is raising new worries about efforts to contain the illness, with infectious disease experts urging greater vigilance in combatting its spread.

More than 20 people, many of them health-care workers, have been reported infected with the Middle East respiratory syndrome coronavirus in two distinct clusters — one in Saudi Arabia and the United Arab Emirates — likely involving human-to-human transmission since early last week.