Boston Mayor Michelle Wu on Thursday announced she had struck a deal with the teacher’s union regarding the city’s vaccination mandate. Under the deal, unvaccinated teachers will be able to lead classes during periods of low virus transmission if they submit two negative tests per week.During high-transmission periods, unvaccinated teachers will not be allowed in school buildings. At those times, they will be allowed to use vacation time as an alternative to unpaid leave. Wu’s office said 84% of union members voted to support the agreement. “This overwhelming ratification vote of a policy that has already boosted vaccination rates across our workforce and will ensure that all new hires must be vaccinated will help us prioritize a safe and healthy environment for students and staff,” said Wu. “We are glad to have reached an agreement with the district that will uplift the health and safety of our educators, students, and communities, while still being able to retain our educators who have chosen to remain unvaccinated,” the union said in a statement. “The agreement takes important steps to promote public health and to mitigate classroom staffing disruptions.” The deal appears to be largely consistent with a proposal the city offered to unions earlier this month. That proposal tied the definition for periods of high and low transmission to three metrics: a community COVID-19 positivity rate of greater than 5%, an intensive care unit occupancy rate greater than 95% and a rate of more than 200 COVID-19 hospitalizations per day.Those same metrics are key to when Wu said the city’s “B Together” COVID-19 vaccination requirement for indoor businesses will end.