Third Lewiston school designated as outbreak site Five cases in 14 days linked to McMahon Elementary, as school closes until January, superintendent said Friday night. Read Article LEWISTON — McMahon Elementary School has been designated a COVID-19 outbreak site based on five cases within 14 days linked to the school. An outbreak is defined by the Maine Center for Disease Control as three or more cases within a two-week period. Lewiston High School was closed for deep cleaning last month when three people tested positive within 12 days. Lewiston Middle School had previously been designated as an outbreak site. Four staff people at McMahon were identified by the CDC as testing positive within a two-week period, Superintendent Jake Langlais announced Friday. Later Friday night Langlais said a fifth teacher was identified as testing positive.