Sunday’s 121st Northeastern University commencement took place at Fenway Park. 4,754 graduate students participated in a morning event, and 4,643 undergraduates celebrated the milestone during an afternoon event.

So far this year, the country has recorded 22 mass killings — all involving guns — that collectively have resulted in at least 115 deaths, according to a database maintained by the Associated Press, USA Today and Northeastern University.

Thousands of Northeastern University students, their friends, and family filled Fenway Park Sunday for the school’s 121st commencement, and its third straight ceremony held at the iconic ballpark.

“Overall some good news here,” wrote Sam Scarpino, an infectious disease researcher at Northeastern University in an email to NPR. “Continuing wastewater, traveler screening, and genome sequencing will be important to ensure the infrastructure is maintained for the next time we need it.”

The data the C.D.C. still plans to collect will not provide enough actionable information at the state and local level, said Sam Scarpino, a public health expert at Northeastern University.

In childhood, the brain of someone with ADHD develops differently and often uses inefficient routes to send messages, according to psychology professor Susan Whitfield-Gabrieli, director of the Northeastern University Biomedical Imaging Center. 

The grim discovery could push the number of people slain in mass killings past 100 for the year, according to a database maintained by The AP and USA Today in a partnership with Northeastern University.