ST. LOUIS (KTVI) — The spread of COVID-19 in schools is rare if proper mitigation strategies are followed, according to a pilot study done at Missouri schools.

The study found that wearing masks, social distancing and frequent hand-washing have kept in-school COVID-19 transmission low.

The study, which included two Missouri school districts and other state and federal departments, was aimed at identifying ways to keep elementary and secondary schools open and safe during the pandemic.

The findings of the study were published Friday in the Centers for Disease Control and Prevention’s journal of Morbidity and Mortality Weekly report. Washington University School of Medicine in St. Louis was part of the pilot study and released the findings in a press release.

The study involved 57 schools in the Pattonville School District in St. Louis County and the Springfield Public School District in Greene County. Two private schools in St. Louis County also participated.

All schools in the pilot study required students, teachers, staff and visitors to wear masks on campus or buses, among other safety measures.

The study included 193 people at 22 of those schools. It was conducted during the first two weeks of December.

The study found 37 participants tested positive for COVID-19. Among those who tested positive, 24 of them were students and 13 were teachers or staff members.

The study also included 156 of the COVID-positive people’s close contacts — 137 students and 19 teachers or staff members.

Of the close contacts who agreed to be tested, only two tested positive, indicating probable school-based, secondary transmission of COVID-19.

“The pilot study demonstrates low transmission in schools and no student-to-teacher transmission — and this was during the height of the pandemic in December, with high rates of community spread,” said Jason Newland, MD, in a press release. He is a Washington University professor who helped lead the pilot program with the CDC.

The study also points out that the Springfield schools followed modified quarantine protocols, allowing some close contacts of positive individuals to remain in school.

The study is part of a larger ongoing collaboration involving the CDC, Washington University School of Medicine in St. Louis, the Missouri Department of Health and Senior Services, the Missouri Department of Elementary and Secondary Education, St. Louis University, St. Louis and Springfield-Greene County health departments as well as several school districts in those two counties.

The larger study is examining the COVID-19 prevention strategies and quarantine policies. The researchers were also going into classrooms to measure the distance between desks to evaluate whether the 6-foot social distancing rule can be relaxed.

On Friday, the CDC said students can now sit 3 feet apart in classrooms. The revised COVID-19 recommendations represent a turn away from the 6-foot standard that has forced some schools to remove desks, stagger scheduling and take other steps to keep children away from one another.