Mayor Michelle Wu and the Dorchester-based Boston Teachers Union have reached an agreement on COVID-19 policies.

When COVID-19 transmission is low, unvaccinated union members will be able to submit proof of two negative tests per week. When transmission rates are higher, “unvaccinated members will not be allowed in school buildings, but may use some accrued time as an alternative to being placed on unpaid administrative leave,” the Wu administration said in a release.

Eighty-four percent of union members signed off on the agreement, which still needs approval from the Boston School Committee. Most teachers are already vaccinated, according to city officials.

“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,” Wu said in a statement.

The Wu administration remains locked in a legal battle with several public safety unions, which have challenged a vaccine mandate for city employees. The unions include firefighters’ Local 718, the Boston Police Detectives Benevolent Society and the Boston Police Superior Officers Federation.

Earlier this week, Wu said the community positivity rate stands at 7.4 percent in Boston, down from 32 percent in early January.