Despite Demonstrated Safety, Efficacy of H1N1 Vaccine, Uptake Levels Still Uncertain

Encouraging news about adult clinical trials involving the novel influenza A (H1N1) vaccine could boost uptake levels, but by how much remains to be seen. "It's still going to be an uphill battle," said family physician Doug Campos-Outcalt, M.D., M.P.A., the Academy's liaison to the CDC's Advisory Committee on Immunization Practices.

Campos-Outcalt, associate head of the department of family and community medicine at the University of Arizona College of Medicine, Phoenix, said he thinks uptake for the new vaccine will be similar to that of seasonal flu vaccine.

In other words, relatively low.

Seasonal influenza vaccine is recommended for more than 80 percent of the U.S. population, but less than 40 percent of Americans receive the vaccine each year, according to the CDC. Moreover, health care workers are urged to get immunized against seasonal flu each year, but CDC statistics show that less than half of health care workers heed the agency's recommendation.

Anthony Fauci, M.D., director of the NIH's National Institute of Allergy and Infectious Diseases, sought to drive home that latter point when he said in an Aug. 21 media briefing that as a health care provider himself, he would encourage his fellow health care workers to be vaccinated, because "it's an important part of providing good quality of care and protecting your patients."

And, in fact, preliminary data from the clinical trials indicate that health care workers who are immunized with the new H1N1 vaccine will be taking a big step toward protecting themselves, their patients and their co-workers. The FDA said in a Sept. 15 news release that the newly licensed H1N1 vaccines induce a robust immune response in most healthy adults just eight to 10 days after a single dose of unadjuvanted vaccine containing 15 micrograms of antigen.

That's good news, said Campos-Outcalt, when one considers that those trials were constructed to determine, among other things, whether an adjuvant would be needed, whether one or two doses would be indicated, and whether 15 micrograms or 30 micrograms of antigen would be required to produce adequate immunity.

"It will mean the vaccine supply will go much further," he said. "The prioritization list will probably be needed for less time, and the fact that you need only one shot instead of two will help uptake."

Multiple studies published before release of the preliminary data from the adult clinical trials had indicated there likely would be resistance to the new vaccine among both patients and health care workers.

For example, Emergency Health Threats Journal reported in August that a study of 11 focus groups conducted in Canada prior to the H1N1 outbreak found that parents and health care workers might refuse to immunize their children and themselves if they think the risks of a new vaccine outweigh the benefits.

A study published online Aug. 25 in BMJ found that less than 50 percent of Hong Kong health care workers reported that they intended to accept a prepandemic H1N1 influenza vaccine, even when the World Health Organization was at pandemic alert phase five. The threat was increased to its highest level -- phase six -- in June.

Moreover, a poll of British nurses by the Nursing Times found that at least one-third of the journal's readers said they don't plan to be immunized with the new vaccine.

Although all three of those studies were conducted in other countries, Campos-Outcalt said he would expect similar responses from American health care workers.

"Maybe we've been too lenient," he said of health care workers' attitudes toward immunization. "Whoever is in charge, whether it is in a physician's office or a hospital administrator, needs to get tough. They should not let health care workers decline without a legitimate reason."

The state of New York is doing just that, mandating that health care workers be immunized against both seasonal flu and the novel H1N1 virus.

Education about basic immunization issues also can help improve uptake, according to a study presented during the CDC's 2009 National Immunization Conference. The study from the immunization branch of the County of San Diego's Health and Human Services Agency and Public Health Services found that health care workers reported several unfounded reasons for not receiving the seasonal flu vaccine, including that they

Preliminary data from H1N1 vaccine trials involving children and pregnant women, which started after trials in healthy adults, are expected within the next week or two, said Campos-Outcalt, and should help bolster confidence in the vaccine's safety and efficacy.