Six new coronavirus cases have been identified in the Martha’s Vineyard Public School system Thursday, making ten since last week as pandemic’s growing case spike continues to loom over the reopening process for Island schools.

In a letter that announced the six new cases Thursday, Martha’s Vineyard school superintendent Matthew D’Andrea advocated for the continuation of in-person learning, saying with confidence that all of the cases were transmitted outside the schools.

Two of the recent cases were reported at the Edgartown school, a third was reported at the Tisbury School and three were reported at the Martha’s Vineyard Regional High School, the letter said.

The six new cases come amidst an unsettling upward trend for the school system, which has seen a growing case-count at both the Tisbury and Edgartown Schools in the past week. Earlier in the week on Sunday, the Tisbury School announced the second case in its community, while the Edgartown School reported its first case on Monday evening.

The three individuals who tested positive at the high school mark the first cases in the public school’s grade 9 through 12 program, which has been meeting largely remotely since the start of the year.

The spate of school-connected cases comes in the midst of a recent case surge on the Island, as daily positive test counts continue to shatter previous records.

Edgartown on Monday moved to postpone their expanded in-person learning schedule for middle schoolers after a positive case was reported at the school, with fifth and sixth grade delayed one week and seventh and eighth grade delayed until Dec. 1. 

But in Mr. D’Andrea’s letter on Friday, he defended the broader reopening process and the schools’ safety and hygienic practices, and said in confident language that the schools were not contributing to the Covid-19 spread on the Island.

“We are confident that in each of these cases, transmission has occurred outside of school,” Mr. D’Andrea wrote. “I have received a number of inquiries about when it would be necessary to slow our student return plan or to move into a full remote model. While it is concerning that the Island is experiencing community spread of the virus, the schools are not a contributor to this spread. None of the student or staff cases we have identified in the schools have been contracted in the school setting. This is because schools are strictly adhering to safety measures to minimize the possibility of transmission, measures that include masking, social distancing, and hand washing.”

In a follow-up conversation with the Gazette on Thursday, Mr. D’Andrea said that he could say with “high confidence” that virus transmission was not occurring in the schools because each case of the virus had been traced back to external exposure.

“We’ve been working with the contact tracers, and in every case they can identify someone outside the school that this person has been around that was positive,” Mr. D’Andrea said. “People who are not students, not staff.”

Mr. D’Andrea did clarify that two of the high school students who tested positive had been “hanging out” outside of school. The letters do not specifically identify the cases as students. In the phone conversation, Mr. D’Andrea said that “most” of the cases did involve students, although he declined to give specific numbers or identifying information.

Reached by phone Thursday afternoon, principal of the high school Sara Dingledy repeated that no clusters had been identified at the school.

“The general protocol is to avoid the need to ever designate anyone as a close contact,” said Ms. Dingledy. “I do know that kids or people are in touch outside the building and it’s the same social circles who may be in the building, but from what I’ve observed…the protocols are working, the students are not getting exposed or contracting the virus in the building.”

In his letter, Mr. D’Andrea’s acknowledged, however, that school re-opening was contingent on a lack of in-school spread.

“If we do encounter spread within any of our schools, we will take the appropriate action in consultation with our Health and Safety Committee and the Massachusetts Department of Public Health. This may involve shifting the affected classroom or school to fully remote, while mitigation strategies are implemented,” Mr. D’Andrea wrote.

The recent cases come after a months-long school re-opening process aimed at bringing the majority of the Island’s student population back to their classrooms on a regular basis.

As of Monday, most students in kindergarten through fifth grade across the Island have returned to in-person learning on a regular basis, with students back for full five-day weeks in certain districts. All other elementary schools are in the process of transitioning, while the high school remains mostly remote.

Mr. D’Andrea’s language mirrors updated state guidelines from Gov. Charlie Baker’s administration that strongly encourage school districts to implement in-person learning, even in communities with high virus incidence.

“With numerous examples of schools reopening from around the world, across the country, and recent first-hand experience here in Massachusetts, it is increasingly clear that schools are not sources of significant COVID transmission, so long as proper health and safety protocols are followed,” the guidelines read. “Districts are expected to prioritize in-person learning across all color-coded categories, unless there is suspected in-school transmission.”

On the Island, school committee members are parents have also urged school leaders to bring students back to the classroom over the past few months, many criticizing the Island’s slow phase-in plan for middle school students.

Since late October, elementary students across the Island have been slowly phasing back into full-week in-person instruction. Plans to re-open middle schools — which have received students just once a week in most districts since September — were officially passed in all Island districts this week.

At the high school, a plan to adopt a new schedule that would divide students into cohorts for partially in-person and partially remote learning, was passed at a high school committee meeting early last week. The plan is set to take effect on November 30.

According to Ms. Dingledy, the school will determine whether or not to postpone the in-person component of the plan in meetings with health officials and school nurses next week. She noted that if the plan is delayed, the new start date likely be December 7, one week later.

Final decisions about re-opening pace and school closures will be determined by Mr. D’Andrea in concert with local principals and the health and safety committee. Decisions will also be informed by state-guidance, Mr. D’Andrea wrote.

In the letter, Mr. D’Andrea stressed vigilant as cases continue to rise.

“Please know that school administration is meeting with our Health and Safety Committee - comprised of our school nurses, Dr. Jeffrey Zack, Dr. Sonia Stevens, and our local Board of Health agents - on a regular basis to discuss the situation on the Island and its impact on our schools,” Mr. D’Andrea wrote. “Our school nurses are working with administration to ensure that all safety measures continue to be followed.”