Several units from the Boston Police Department responded after the threat was received at around 11.40am on Friday, a spokesperson told NBC Boston.
The hospital did not offer any comment, according to NBC Boston, and did not immediately respond to a request for information.
On 30 August, the hospital received a bomb threat that forced staff and patients to be evacuated and nearby streets to be cordoned off.
No threat was discovered, and no-one was injured.
It came after the hospital said it had received waves of threatening phone calls and online messages earlier in the month that were related to the hospital’s treatment of transgender youth.
The hospital is home to the Gender Multispecialty Service, the nation’s first pediatric and adolescent transgender healthcare programme.
Far-right influencers and anti-trans activists had promoted false claims that the hospital performed gender-affirming hysterectomies on children under 18 years old.
Only “eligible adolescents and young adults” can receive treatment, and “genital surgeries are only performed on patients age 18 and older”, according to the hospital.
In a statement last month, the hospital said: “We are deeply concerned by these attacks on our clinicians and staff fueled by misinformation and a lack of understanding and respect for our transgender community.”
Chidlren’s hospitals in Omaha, Nebraska and Pittsburgh, Pennsylvania, had also been targeted by ant-trans activists in recent months, according to NBC News.
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