PITTSFIELD — From the Berkshires to Cape Cod, the flu bug is biting Massachusetts hard, as a spike in confirmed cases has local and state health experts urging vaccination and prevention.

The last week in December saw 220 confirmed cases of influenza A across the commonwealth — a 44 percent increase — bringing the flu season total to 502, according to the state Department of Public Health. The DPH website reported the less severe influenza B jumped 69 cases to 177 to date.

The flu bug surge coincided with the Arctic cold that has gripped the Northeast since Christmas day — but it's just that, a coincidence, said DPH epidemiologist, Dr. Alfred DeMaria Jr.

"The season started when the weather was unusually warm in November, but the flu can show up anytime," noted DeMaria.

Locally, Berkshire Health Systems has confirmed more than 50 cases combined of influenza A and B over the past two months with 20 patients suffering from the flu admitted to Berkshire Medical Center during that time, BHS officials said Wednesday.

With the illness now widespread throughout Massachusetts, BHS has issued visitor restrictions at BMC, its Hillcrest and North Adams campuses and Fairview Hospital in Great Barrington.

"If someone is recovering from a disease or illness, the last thing they need is getting something else," said Michael Perreault, a registered nurse.

People should not visit patients at any BHS facilities if they are under 18 years of age, ill or are experiencing flu or flu-like symptoms. Those symptoms include fever, chills, body aches, coughing or fatigue.

The visitor restrictions are in effect through the rest of the flu season, which can extend into early May, health officials said.

Despite reports that this winter's flu vaccine has been less effective than in previous years, getting the shot is better than no shot at all.

The effectiveness is based on the immunized person's age and health of the person.

"The younger and healthier you are, [the] better the effectiveness of the vaccine," said DeMaria.

BHS officials noted flu shots are still available across the region through primary care physician offices and pharmacies.

Flu shot or not, basic hygiene remains crucial to warding off all winter ills. Health experts say it begins with hands-on prevention.

"Whether you are at home or work, hand washing is important to prevent the spread of illness," Perreault said.

If sick, Perreault, DeMaria and the federal Centers for Disease Control urge people to stay home from work, social functions and other gathering places to avoid spreading the flu, common cold and other viral illnesses.

Dick Lindsay can be reached at rlindsay@berkshireeagle.com and 413-496-6233.