WILLIAMSTOWN, Mass. — Williams College saw the expected number of positive COVID-19 test results in its student population as it moved into the spring semester, officials said on Thursday.

 

Most of those positive tests were found among students before they returned to campus.

 

"We were kind of running three different [predictive] models, all using publicly available data sets," said Jason Rivera, the college's director of institutional research. "What it was doing was giving us a range of where we could possibly expect cases to go depending on how you want to plug in the numbers.

 

"As we got closer and closer to students arriving, we were looking at somewhere between 15 and 20 students who were likely to be positive based on where our students were coming from."

 

In the last seven days, the college's testing program has reported 11 positive results, all in the student population, officials said. Those are in addition to 14 students who tested positive before arriving on campus and were asked to remain at home until they were cleared by local medical officials.

 

Eleven cases — or 25, depending on how you look at it — is up dramatically from the start of the fall semester. Since the advent of college's testing program for students and staff on Aug. 17, there have been 35 positive tests, meaning 31 percent of those positives have come in the last week.

 

And more than half of the 18 total positive tests among students have come in the last seven days.

 

But it also is worth noting that the college program's seven-day positivity average, based on 11 positives and 4,476 tests, is 0.25 percent, well below Massachusetts' statewide seven-day positivity rate of 2.13 percent or Berkshire County's 14-day positivity rate of 1.1 percent.

 

The recent bump of positive tests among students, who have largely not been on campus since the start of the Thanksgiving weekend, was predictable based on nationwide trends.

 

"It is obviously higher than what we saw when students were here in the fall, but you have to remember that the national COVID rates in the fall versus what we saw in January and February were drastically different," Rivera said.

 

Williams' vice president for finance and administration, who co-chaired the school's working group on reopening in the fall, put those differences into perspective.

 

"On the first day of arrival in the fall, the nationwide seven-day average of cases was 43,000, this spring, it is 105,000," Fred Puddester said. "And, importantly, two weeks prior to arrival the nationwide numbers were 47,000 [in the fall] and 165,000 [this winter]." 

 

Rivera said he looked at national COVID-19 numbers in the summer in preparation for the fall semester but was not able to run the same kinds of models he ran in January and early February because good data was not as readily available at the time.

 

But in retrospect, the data modeling he used for the spring semester would have done a good job anticipating the positivity rate in the fall.

 

"One of the models that we've been using, it's one of The New York Times models, that was pretty predictive," Rivera said. "We were able to use the data that we had and the rates — we kind of backdated things — that was pretty close to what we saw in the fall. That's why we were comfortable moving forward with what we were seeing and the projections this time around.

 

"We had something we could trust on that front."

 

The students who tested positive on their return to campus were placed in isolation on campus according to the college's protocols and procedures.

 

In addition, 20 students who were considered "close contacts" of those who tested positive were quarantined in campus housing where they will be monitored for symptoms and tested before they are allowed to have the run of the campus.

 

And, as it did in the fall, Williams is restricting students' movement to the campus, including Spring Street, and selected exercise venues in town. The school once again will assess the rate of community spread of the novel coronavirus before deciding whether to ease up on that restriction.

 

College administrators said that once again they are happy to see the level of students' compliance with masking, social-distancing and college-specific rules around preventing COVID-19 spread. They are more concerned about compliance in the rest of the community.

 

"I was just out and about, and there were two police officers standing next to each other, unmasked having a conversation," Williams Associate Vice President for Finance Matt Sheehy said. "That's not exactly the public health campaign that you want.

 

"But I think the students overall are doing a very good job. It's something that we're monitoring. I think that was one of the great successes of the fall, how well our students took it, and we continue to stay on top of that with them."