Approximately 70 Whittier Street Health Center employees, including doctors and social workers, will be unionized after a majority of the eligibile employees voted in favor of joining 1199SEIU on Wednesday, marking the first community health center in Massachusetts to unionize professional clinical staff. The union vote took place throughout the day Wednesday, into the evening, and ended with 50 employees voting in favor of joining the union, with nine voting against, according to one Whittier employee.…