New York City’s teachers union is calling on Mayor Bill de Blasio to intensify COVID-19 testing efforts on children younger than 12 years old, who aren’t yet eligible to be vaccinated. In a letter to the mayor, United Federation of Teachers (UFT) President Michael Mulgrew argued that the city should restore its previous testing frequency. Under the most recent guidelines from the city’s education department, random testing was reduced to 10 percent of unvaccinated students on a biweekly basis from the 2020 weekly requirement of 20 percent of the school population. “I am concerned that this year’s reduced frequency of COVID testing means that thousands of children will spend days in classrooms without the early warning system that last year made our schools among the safest places in the community,” Mulgrew said. Mulgrew noted that fewer than half of the city’s more than 1,800 schools and sites were tested in the …