HCWs got flu vaccine — but not for H1N1

Interest waned by time pandemic shot available

Hospital employees stepped up for influenza vaccinations at an unprecedented rate this year, but there was just one catch: Many of them received the seasonal flu vaccine but not the H1N1 vaccine. That left them protected against strains that did not circulate this year, but unprotected against the novel H1N1 transmission that continued in some states through the winter and spring. The problem lies in a mismatch between motivation and vaccine supply.

At the height of concern about pandemic influenza, only the seasonal vaccine was available. By the time the H1N1 vaccine was readily available, it was perceived as a mild to moderate illness and concern had abated, says Gary Euler, DrPH, senior epidemiologist with the Immunization Services Division of the National Center for Immunization and Respiratory Diseases of the Centers for Disease Control and Prevention in Atlanta.

It proved more difficult to get health care workers to return for a second vaccination. While 71.7% of hospital-based health care workers reported receiving the seasonal flu vaccine, just 50.6% of them received the H1N1 vaccine, according to a survey conducted by the RAND Corp. for the CDC.1 Not surprisingly, hospitals with mandatory vaccine programs had higher rates of vaccination than those with voluntary compliance. About 21% of hospital-based health care workers reported that their facility required influenza vaccination, the survey found. CDC stopped short of recommending mandatory vaccination, but noted the impact of the trend.

"We don't discourage mandatory policies," says Euler. "We have experience with how well that works with children in schools. [Such programs] will be very effective as more and more hospitals adopt it."

In a press briefing, Anne Schuchat, MD, director of the National Center for Immunization and Respiratory Diseases, noted that well-organized voluntary programs also produce results.

"We would love to see health care institutions report the coverage that they achieve and really start competing with each other...so that patients can know, 'That's a hospital that really received a higher rate of protection among their health care workers,'" she said. "There are a lot of strategies to be explored in the future."

Demand for flu shots started strong

As flu immunizations began last fall, employee health and infection control practitioners were initially pleased with the surge of interest from health care workers. "The interest in seasonal influenza immunization was the highest we've ever had," says William Schaffner, MD, an infectious disease expert who is chairman of the Department of Preventive Medicine at Vanderbilt University in Nashville. By the time the H1N1 vaccine arrived, later in October and November, the interest had waned, he says.

"Unfortunately, it took somewhat longer than expected for us to receive the H1N1 vaccine and it came out in successive shipments," says Schaffner. "The vaccine became readily available when the outbreak was abating."

Meanwhile, H1N1 transmission stubbornly persisted through the winter and early spring. In fact, in late March, the CDC reported local and regional activity in the Southeast, including a spike in influenza-related hospitalizations in Georgia that was higher than at any time since October. Schuchat urged those who remained unvaccinated to seek out the vaccine.

Yet the influenza vaccine seemed to have a short window of acceptance. The CDC collaborated with the RAND Corp. to monitor vaccine coverage on a monthly basis from December 1, 2009 to June 30, 2010. An online survey of a nationally representative sample of 1,417 health care workers asked about vaccinations that occurred beginning in August 2009.

Most health care workers received their vaccines in October and November, the survey showed. "The data we have does not show a lengthening of the vaccination period," says Euler. "That's an area we have to work on. I was surprised vaccination did not extend into December."

By January, few additional health care workers received the H1N1 vaccine.

Reasons for decline are familiar

Why did health care workers fail to receive the vaccine in the first declared influenza pandemic since 1968? Supply constraints played a role, at least initially. Although CDC has emphasized that health care workers caring for vulnerable patients are among the highest priority for vaccination in a pandemic, health care workers often worry during a vaccine shortage that they will take vaccine from patients who need it.

About one in five (21%) unvaccinated health care workers cited concerns that "others need the vaccine more than I do" as one of their top three reasons for not receiving the vaccine, says Katherine M. Harris, PhD, senior economist at RAND.

"They don't want to be seen as the ones taking all the vaccine available, even though they probably should be vaccinated first," says Euler.

Fortunately, the message that health care workers need to be vaccinated to protect their patients did resonate with some. Health care workers who reported that they worked in intensive-care, burn, or obstetric units or with "seriously ill" patients were more likely to receive either vaccine. Physicians were slightly more likely to receive the seasonal flu vaccine than nurses, but both physicians and nurses received the H1N1 vaccine at similar rates (44.7% and 44.5%). Other reasons for failing to get the H1N1 vaccine mirror the explanations that health care workers give when they decline the seasonal vaccine. Although health care workers were more likely to state that they believed the seasonal flu vaccine was safe (80.6% compared to 66.6% for the H1N1 vaccine), fear of side effects was cited at the same rate by those unvaccinated for either vaccine (22% for the seasonal flu vaccine vs. 23% for H1N1). Schaffner says he knew of health care workers who expressed concern about the H1N1 vaccine because it was "new" – although the manufacturing process was identical as for the seasonal flu vaccine and the vaccine uses an inactivated virus.

"There was no basis then [for concerns] and subsequent intense surveillance has confirmed there were no safety issues with the vaccine," he says. The other most frequently cited reason for not receiving the vaccine: "I don't need it." That indicates the continuing need to educate health care workers, says Euler. After all, although the survey indicates that 64.3% of health care workers received either the seasonal or H1N1 vaccine (or both), meeting the "Healthy People 2010" goal of 60%, there is still much work to do. The proposed goal for "Healthy People 2020" is influenza vaccination of 90% of health care workers.

"I think we need to promote safety and effectiveness, and the protection of the patients and family members," says Euler. "We are seeing that message resonate more and more as time goes on."


1. Centers for Disease Control and Prevention. Interim results: Influenza A (H1N1) 2009 monovalent and seasonal influenza vaccination coverage among health-care personnel – United States, August 2009-January 2010. MMWR 2010; 59:357-