RALEIGH — A one-day flu vaccination blitz for health care workers that began at Duke University Heath System last year is now an annual event, spreading to more than a dozen clinics and hospitals across the Triangle.

The 24-hour mass vaccination for the coming flu season begins Wednesday morning with two goals: To inoculate as many of the more than 15,000 health care workers as possible, and to practice the regional response to a pandemic. Emergency response teams simulated deliveries of vaccine Tuesday from the state’s strategic stockpile.

Having high rates of vaccination among doctors, nurses and other hospital workers is critical, because they can easily transmit flu to patients who are among the most vulnerable to serious complications from illness. That includes those with asthma, diabetes and chronic lung disease, pregnant women, children younger than 5 years old and adults 65 and older.

One reason that flu is particularly tricky to fight is that those who contract it can be contagious well before they show symptoms.

“Even if you’re not a doctor or nurse, but, say, at the front desk, you can still be exposing the patient across from you,” said Dr. Linda Butler, the chief medical officer at Rex Healthcare.

The blitz gives the various hospitals and clinics a chance to practice the logistics involved in obtaining the vaccine, smoothly distributing it to various sites and then getting workers injected, Butler said.

It’s crucial in an emergency to be able to quickly inoculate front-line health care workers so they can remain healthy to help the rest of the region’s population.

At Rex, the shots are mandatory. Only a handful of workers will be exempt, mainly for medical reasons, Butler said.

Rex, which didn’t participate in the blitz last year, has long tracked its vaccination rate, which was about 75 percent of its workers in 2011. The hospital hopes to reach at least 90 percent this year, said Butler.

Last year, Duke was able to get more than 80 percent of its workers vaccinated and aims to increase its rate to more than 90 percent.

The timing, about eight days earlier than Duke’s blitz last year, was aimed at making sure health care workers were vaccinated before they begin dealing with many flu patients.

In the United States, the flu season usually starts in October or November and winds down in March or April.

Vaccine ads get earlier

In recent years, more pharmacies, supermarkets and “big box” stores with pharmacies have begun offering the vaccinations, and the advertisements they run well before the end of summer raise the question of when is too soon for a flu shot.

Steve Adkins, owner of Health Park Pharmacy in North Raleigh, felt compelled to put out a news release at the end of August urging people to ignore the ads, that it was too early. Adkins said he became troubled when a competitor began advertising at the beginning of August.

“I thought it was just getting ridiculous,” he said.

Now, though, is a reasonable time to get vaccinated, since it takes two weeks for the effects of the vaccine to reach full strength, he said.

Tom Skinner, a spokesman for the Centers for Disease Control and Prevention, said it’s true that the vaccine’s strength wanes over time. Still, it lasts long enough that someone vaccinated in late August should have plenty of protection through the end of flu season.

Part of the reason that the focus on flu shots may seem to have begun earlier is that greater quantities of vaccine are being made, more places are offering it and more people are getting vaccinated, Skinner said.

“And that’s a good thing,” he said. “The bottom line is, you need to be protected, and the vaccination is the best protection there is.”

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