When the Legislature approved the creation of a statewide immunization registry in 2016, the consensus among health care providers was that it was about time.

New Hampshire was the last state in the country without a database that allowed doctors to access their patients’ complete vaccination history, but lawmakers appeared to have finally worked out the kinks and privacy concerns that led previous attempts to fail.

Nearly three years later, however, New Hampshire still doesn’t have a working immunization registry due to a series of technical glitches and concerns about the vendor, Arizona-based Scientific Technologies Corporation, which received a $1.4 million contract in 2014 to build the system.

“As we began to work with them to implement it for New Hampshire, they began to start releasing new versions of their product and planning a complete overhaul,” said Beth Daly, chief of the state’s Bureau of Infectious Disease Control. “We were concerned about whether the product was still right for New Hampshire. We want it to be successful so that people will want to voluntarily join it.”

The previous vendor’s contract expired on Jan. 31 and the Department of Health and Human Services plans to go back out to bid.

It will likely be years before everybody who wants to use the registry to store and access their immunization history is able to do so, Daly said.

When it does come online, residents will have the option to opt out.

The registries have a number of uses.

If you are looking to enroll your children in school, travel abroad, or apply for a job that requires documentation of your vaccinations, the only way to get a complete history is to go to every doctor and pharmacist who has administered a shot and ask for the records in their office.

Over the course of a lifetime, that could be a significant number of different providers.

But the registries also help cut down on wasteful spending on redundant shots and reduce the risk of rare side effects, said Dr. Tessa Lafortune Greenberg, chair of the pediatrics department at Dartmouth-Hitchcock and the newly elected president of the New Hampshire Medical Society.

“Being able to have a good, consistent record of vaccines for patients is huge,” she said. “You can’t assume they had things they didn’t … (but) you don’t want to give anyone something they don’t need. It puts them at risk — you’re sticking a needle in their arm so there’s risk of infection, there’s risk of reaction.”

When Lafortune Greenberg took over as president of the New Hampshire Medical Society she decided to make increasing immunization rates one of her priorities.

New Hampshire has one of the best vaccination coverage rates in the country. As of 2017, nearly 88 percent of Granite State children had received the three-vaccine series that the U.S. Centers for Disease Control and Prevention uses as one metric to measure coverage. Only Massachusetts, Virginia and Maine had higher rates.

But Lafortune Greenberg said that it is becoming more common to see parents refuse to vaccinate their children due to junk science and warnings issued by misinformed celebrities.

“Back around 2000 there were reports that we had gotten rid of some of these diseases in the United States and now we’re seeing them come back and it’s hard to see that,” she said.

Immunization registries are also valuable tools in cases of outbreaks.

The push to create the databases began in the 1990s, spurred by a series of measles outbreaks, said Rebecca Coyle, executive director of the American Immunization Registry Association.

Minnesota used its registry during a measles outbreak in 2017 — the largest the state had seen in nearly 30 years — to efficiently direct education and outreach efforts into the affected communities and prevent the disease from spreading further.

“They were able to look at a class roster very quickly and identify which children were at risk, which allows you to target your response very quickly,” Coyle said.

Those are the kinds of big-picture, cost- and life-saving uses New Hampshire officials envision for their registry once it gets running.

Dr. David Itkin, an infecious disease specialist at Portsmouth Regional Hospital, said that in a community like Somersworth, which has a large immigrant population, there is likely to be an immunization gap because vaccination is not part of a child’s regular series of shots in many countries.

If medical professionals knew there was an exposure and could reach out to that unvaccinated group of people, they could stop the spread of measles because a vaccination can be administered up to 72 hours after exposure, he said.

Correspondent Kimberley Haas contributed to this report.