The city is hosting its second free flu vaccination clinic for children and adults on Saturday. The clinic is 9 to 11 a.m. at the Stamford Government Center, 888 Washington Blvd. No appointment is needed. Stamford’s event is part of a statewide campaign launched by the Department of Public Health in response to the severe flu season. Flu season begins in late fall and usually peaks in mid to late winter and can continue through early spring.