The calendar says mid-April, everything is turning green, the birds are singing, and yet in many parts of New Jersey there are reports of increased influenza-like illness.

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"There seems to be a spike in what we call type B influenza," said Dr. Sal Bernardo, chairman of the New Jersey Academy of Family Physicians. "We usually see what occurs in late January, and that's typically what they call type A."

Bernardo said even if you already had the flu this past winter, it's entirely possible you'll get it again.

"Although many people see getting the influenza vaccine as protecting them from all types of flu, it's really not true," he said, "because there are many, many different strains of virus -- type A, type B and whatnot."

In preparing the influenza vaccine, according to Bernardo, the Centers for Disease Control and Prevention does surveillance and ultimately picks three or four virus strains. Those decisions guide the organization in making vaccines for the upcoming year.

Bernardo said while treating his own patients in Freehold, "we vaccinated them and they actually wound up in the emergency department at the local hospital with flu-like symptoms, and they did the nasal swab and it was positive."

He said CDC data shows only 40 percent of people have been vaccinated for the flu, so coming down with a form of the virus isn't really that unusual.

"One of the things we all see is basically just a spike of viral-type illnesses in the spring," Bernardo said. "Whenever it's warm and cold like this, we'll typically see spikes of these flu-like illnesses in the spring like this; and in the early fall, it's just a breeding ground for viruses."