ANDOVER — Swine flu appears to have hit the Merrimack Valley, sickening a growing number of children and adults throughout the region last week just as a small number of doses of the vaccine began trickling into public health agencies.

Holy Family Hospital in Methuen has confirmed eight cases since last Tuesday. Merrimack College in North Andover said 20 students have been sent home with a flu-like illness, at least some of them believed to be the H1N1 virus. And the head nurse for the Andover schools said a number of students, staff and relatives of children have all recently been affected by symptoms resembling the swine flu.

"Toward the end of last week, we started seeing more cases," said Rita Casper, director of nurses for Andover public schools. "But it's not just students."

A spokesman for Pentucket Medical Associates, which has pediatric offices in Haverhill and Lawrence, said a spike in flu cases started last week.

"Reports are coming in from everywhere," said Bill Plante. "It's clearly on us now."

While the New England region saw a relatively benign 9 percent increase in flu-like cases reported the week of Oct. 11, that number is likely to rise significantly once new statistics come in for last week.

But the vaccine isn't coming as quickly. Lawrence and North Andover health boards each received 100 doses from the state, far too few to offer a clinic. Andover received a small allotment too, while Haverhill and Methuen have yet to receive a single dose.

Andover Health Director Tom Carbone said he was trying to determine exactly what to do with the few doses he has received. He stressed that while it was not enough vaccine for a clinic, "I don't want it to go to waste just sitting in my refrigerator."

Thomas Trowbridge, chairman of the North Andover Board of Health said the vaccine came from the state without any information as to who should receive it. The state told North Andover yesterday to start distributing it through obstetricians' offices. Lawrence gave its doses to local pediatricians who hadn't received the vaccine.

"They've realized we can't hold onto this," Trowbridge said. "So we are working to get it out to high-risk patients. We are trying to get it sorted out."

Sorting out who gets the limited number of vaccines has been an issue at hospitals, clinics and doctors' offices as well.

The Women's Health Center on Water Street in Haverhill recently received about 100 doses of the vaccine and is going through its patient list to see which pregnant women are at highest risk and most in need of the vaccine.

"Unfortunately, it's going to be very difficult for us to dispense the vaccine," said Ann Marie Tinkham, practice administrator. "We are looking through our patient load to see who's at highest risk. It's a very hard decision. We want to give shots to all of our OB patients, but right now, the highest risk population is the only population we can take care of."

Pentucket Medical Associates must make a similar decision about who is going to get the vaccine. Plante, the spokesman for the group, said small amounts of the vaccine have been trickling in, and that some has already gone to health care workers.

"We needed to do more than 300 employees," he said. "Only a third have been vaccinated."

Meanwhile, the practice also has been trying to accommodate the needs of children who are high-risk patients.

"We have to allocate to high-risk kids," he said. "It's a very fluid situation."

At Holy Family Hospital in Methuen and Lawrence General Hospital in Lawrence, the focus has been on vaccinating staff as well as preventive measures. Both hospitals posted signs yesterday that no visitors under the age of 18 are allowed inside either hospital.

Danielle Perry, spokeswoman for Holy Family, said hospitals are not supposed to be administering the vaccine to the general public.

"Our goal is to vaccinate anyone doing patient care," she said, adding that nearly 90 percent of the 1,500 employees at the hospital have received the seasonal flu vaccine, much higher than normal. A much smaller number of staff have received the H1N1 vaccine.

Andrea Eobstel, spokeswoman for Lawrence General, said 300 staff members have been vaccinated to date, and another 300 doses are available for staff.

"The hospital expects further shipments, but we don't know when," she said. "In the meantime, we are focusing on the highest-risk employees."

Marianne Bitner, director of clinical services at Trinity EMS Inc., an ambulance company that services Haverhill and Southern New Hampshire, said none of the EMTs who work at Trinity have been vaccinated, even though they are high on the list of people who were supposed to receive it.

"We are seeing an increase in flu-like symptoms in patients being transported in all the towns and cities where we have contracts," she said. "It really concerns me we don't have vaccine for first responders, EMTs and firefighters."

Her company, once it receives the vaccine, will also vaccinate Haverhill EMTs.