02 Dec 2006

A federal plan to vaccinate hospital healthcare workers against a threat of smallpox fell short on several levels, according to the first metric analysis of the prophylactic health program. Results of the Temple University study raise troubling questions about future preparedness against possible outbreaks of avian flu or SARS.

The study, "Preparedness for a smallpox outbreak: comparing metrics for assessing levels of vaccination among health-care workers by state," has been published online ahead of print in the journal Epidemiology and Infection.

In 2003, the Centers for Disease Control and Prevention asked each state to vaccinate at least 50 to100 healthcare workers per hospital, a number the government considered large enough to respond to a possible smallpox outbreak. These workers could then vaccinate and treat others.

Doses of smallpox vaccine were distributed nationally based on each state's requests, with a goal of vaccinating 500,000 workers in 30 days. Yet by mid-2005, only about 39,000 - or 17 percent of the requested dosages - had been used.

"Some states requested thousands of vaccines, while others only a few hundred," said lead researcher Sarah Bass, Ph.D., MPH, assistant professor of public health in Temple University's College of Health Professions.

To critically examine how well the program worked, researchers analyzed vaccination patterns based on a series of metrics: the absolute numbers of health care workers vaccinated compared to the percentage of doses distributed to each state, the rate of vaccination per capita population, and the percentage of healthcare workers vaccinated compared to the number recommended by the CDC. States were then ranked into four quartiles.

"We had to do a very careful analysis because some states appeared to have a very high vaccination rate if you only looked at the number of absolute vaccinations as a percentage of the number of vaccines requested," Bass said.

Oklahoma, for example, vaccinated 376 people with the 700 doses requested - slightly more than 50 percent. However, the state would have needed an estimated 9,675 doses to meet the CDC's recommendations, which leaves Oklahoma's true vaccination rate only at 3.9 percent of the goal set by the CDC.

Overall, researchers found a generally low compliance rate along with a great variability among states. States most affected by 9/11- New York, Pennsylvania and Virginia - ranked in the bottom quartiles of most metrics, while several states perceived to be at a lower terror risk, such as Nebraska, ranked at the top.

While the lack of an impending smallpox crisis may account for the differences in state response, both the federal and state governments could have done a better job, Bass said.

"Some felt the CDC or state health departments sent ambivalent messages about the importance of the program, and many states did not fully support the effort," Bass said. "The result was a very inconsistent uptake of the vaccination program by states, where some states had very coordinated efforts and others did not."

Adding to the variability were many healthcare workers who didn't believe that the benefits of the vaccine outweighed the personal risks.

"Workers worried that the vaccine, which had not been given to middle-aged or older adults in the past, might have unanticipated dangers. Others wondered if the vaccine might be effective against newer forms of weaponized smallpox," said Bass.

To uncover why healthcare workers did not accept vaccines, Bass, along with colleagues Tom Gordon and Sheryl Ruzek, is working on a new study that employs perceptual mapping to evaluate how healthcare workers balance risks and benefits in deciding whether or not to take part in a vaccination program.

"To be prepared, we need to have health workers protected," Bass said. "But as long as it's a decentralized program without an immediate outbreak, it will be difficult."