MANCHESTER (AP) — Several Connecticut school districts have been forced to close or stop in-person learning for a day, after educators attending vaccine clinics called in sick with side effects from the shot.

Manchester schools reported a shortage of teachers and bus drivers on Monday after a vaccine clinic for educators was held there over the weekend.

"I understand the challenges this causes for parents and families and had hoped to avoid going remote for the day," Matt Geary, the town's school superintendent wrote to the community Monday. "I apologize for the inconvenience."

A similar incident caused a Colchester elementary school to close for a day last month and forced Stamford schools to delay a return to in-person learning for one day.

In Region 13, which includes Durham and Middlefield, officials proactively scheduled a day off for Monday after a clinic was scheduled on April 3 to give educators their second vaccine dose.

"The good news is that we held one snow day in reserve for this exact scenario, so we do not need to adjust our calendar or change the graduation date," Superintendent Doug Schuch wrote.

Southington officials made a similar decision last month, giving staff a day off the Monday after a March 14 clinic.

Typical side effects of the vaccines include pain, redness and swelling on the arm the shot was administered to and tiredness, a headache, muscle pain, chills, fever and nausea, according to the Centers for Disease Control and Prevention.

In other coronavirus-related news:

COVID CYBER CRIME

The shift over the past year to remote work prompted a large increase in phishing and other cybersecurity threats during the initial months of the COVID-19 pandemic, according to a new report released Monday by Connecticut's Public Utilities Regulatory Authority.

The annual Public Utilities Critical Infrastructure Report assessed last year's cybersecurity vulnerabilities and policies of regulated electric, gas and water utilities. It found that utility company cybersecurity programs had to quickly scale up in order to enable employees to connect remotely and safely to company networks.

"In general, this massive societal shift to remote work prompted malicious actors as a whole to change priorities," according to the report. It noted that while the frequency of ransomware attacks generally declined because schools, businesses, and other organizations stopped or scaled-back operations, more phishing attempts were made against personal accounts and systems, as well as virtual meeting platforms.

The report also found third party vendors that provide external services to utility companies remained vulnerable.

The report also found "an undeniable increase in activity from state sponsored actors," including Russia, China and Iran.