Abruptly, a surplus of shots for H1N1

As a result, Massachusetts health authorities may decide as early as today to offer vaccine to anyone who wants it, lifting restrictions that limited vaccine to children and adults at greatest risk of complications.

The public’s interest in being vaccinated, health authorities report, is waning even as factories churn out shots and nasal spray at a breakneck pace, creating the prospect of millions of unused doses. With the pandemic’s second wave in retreat and the holidays imminent, health authorities surmise, patients in Massachusetts and nationwide may no longer possess a sense of urgency about being vaccinated, nor go out of their way to get a dose of protection.

“We are interested in making it easy for people to get vaccinated,’’ said Dr. Beth P. Bell, a vaccine specialist at the US Centers for Disease Control and Prevention. “There are lots of different strategies and ideas out there that can be customized for local conditions, but all of them begin with the idea of putting the vaccine in people’s paths.’’

In Massachusetts, that could translate into flu-shot depots outside the local Macy’s or inside the neighborhood grocery store, said John Auerbach, the state’s commissioner of public health. This morning, a telephone conference call conducted by Auerbach’s agency is expected to end with a date set to make vaccine more broadly available.

“The time has come to consider opening up vaccine to the general population,’’ Auerbach said. “We are very concerned about the waning interest.’’

The diminishing desire to be immunized was evident two weekends ago when Boston held its first large-scale public vaccine clinics, restricted to people at risk of serious complications from the flu. Nurses from the Boston Public Health Commission arrived in Hyde Park and West Roxbury armed with 10,000 doses. When other local health departments - such as Wellesley’s - dispensed vaccine in October as swine flu cases were increasing, lines formed early and snaked hundreds of people long.

But on that first weekend in December, the Boston authorities gave out barely 2,000 doses.

“With the holiday season upon us, it’s a hard time to get people to focus on something that doesn’t have a real sense of urgency around it any longer,’’ said Barbara Ferrer, executive director of the Boston Public Health Commission. “Our messaging for three months has had to be, ‘Just hold on - you’re going to get it.’ Now people say, ‘I’m really busy now, and what’s the difference anyway?’ ’’

When six local health departments in the Merrimack Valley banded together this past Saturday to provide vaccine against the H1N1 virus to high-risk patients and people who take care of them, authorities steeled themselves for an onslaught, expecting to administer 1,400 doses.

“We had all sorts of stations set up, expecting pretty heavy demand,’’ said Frank Singleton, Lowell’s health director. “There was some demand, but we only got 797 by the end.’’

And when Tyngsborough provided vaccine earlier in the month, health officials resorted to pleading with patients to call their families and friends to urge them to come down for a shot.

“The whole strategy is going to have to change at the Department of Public Health,’’ Singleton said. “They’re going to have to beg people to be vaccinated. I think we’re going to have a whole lot of vaccine unused at the end of this process.’’

The federal government has contracts to purchase 250 million doses of swine flu vaccine, and by Monday, nearly 93 million doses had been manufactured. The pace of production has hastened dramatically: The number of available doses increased by 20 million in just the past week. Massachusetts has received more than 2 million doses but expects an additional 1.5 million.

So what began as a trickle in early October has turned into a river of vaccine, a reflection of the antiquated, unpredictable science of flu vaccine production, which relies on a decades-old process of growing doses in eggs.

An announcement by the CDC yesterday that 800,000 pediatric doses of vaccine were somewhat less potent than originally believed may further dampen people’s interest in being immunized, public health specialists fear. Some of that vaccine was sent to Massachusetts, although state authorities said they were still waiting to find out how much.

The CDC is asking pediatricians to return unused doses of the weakened vaccine but said children who received the shots do not need to repeat the process.

There continues to be strong demand for vaccine in some locales. Brookline, for example, had a robust response to a vaccination campaign the first Sunday in December. And at Massachusetts General West Medical Group in Waltham last night, there were “wall-to-wall kids’’ waiting for vaccine, said Dr. Victoria McEvoy, chief of pediatrics there.

“Parents have worked so hard to get it, by calling every day, several times a day, and feeling the frustration with not having it,’’ McEvoy said. “Many of them signed up weeks ago to get into our clinics, and now that we have vaccine, they’re going to get it.’’

Globe correspondent Elizabeth Cooney contributed to this report. Stephen Smith can be reached at stsmith@globe.com.