13 October 2006
Study Looks at Ways To Stretch Pandemic Flu Vaccine Supplies
Vaccine research advances, and social strategies to control pandemic explored
Washington – Research funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the U.S. National Institutes of Health, provides promising new evidence on a way to stretch limited supplies of vaccine in the onset of pandemic influenza, according to findings reported at the Infectious Diseases Society of America October 13.
Pandemic influenza begins with a viral strain to which humans have little immunity. That is why a pandemic spreads rapidly and causes broad waves of illness.
In that event, scientists will work furiously to develop a vaccine specifically targeted to the previously unknown strain. But even after they develop the new vaccine, production capacity will be inadequate to meet widespread need.
Adequate protection likely would require at least two inoculations per person, a further strain on supplies and on a health care system that might be overwhelmed in the effort to care for the sick.
Research conducted by a scientific team at the University of Rochester in New York explores the idea that patients might be protected better by a small dose of the vaccine for the newly emerged strain of influenza if they had previously been vaccinated against a related strain.
Would the response to a related strain that is not causing pandemic “be beneficial for people if you ‘primed’ them ahead of time? We didn’t know the answer to that,” said NIAID Director Anthony S. Fauci.
“Yes” is the tentative answer delivered by the University of Rochester study. Half of the subjects participating in the research produced substantial antibody levels after just one dose of the H5N1 vaccine if they previously had been inoculated with a vaccine developed to counter a similar strain.
The 37 subjects in this study had participated in an earlier NIAID vaccine trial conducted in response to a 1997-1998 outbreak in Hong Kong, the first occasion that avian influenza was known to infect humans.
When these subjects were vaccinated against a strain that occurred in Vietnam in 2004, they produced a stronger immune response than subjects who received only a vaccination against the more recent strain.
“The boosting, even seven or eight years earlier, provided a benefit in the response,” Fauci said in a Washington File interview. “So … that provides some scientific credence, or scientific basis, for the concept that priming people ahead of time may be beneficial.”
This finding will be pursued aggressively with further study, Fauci said, noting that a very small number of subjects participated in the Rochester work. He said future trials will involve larger numbers of people and the use of vaccines derived from other strains.
The H5N1 virus that has killed 149 people in 10 countries since late 2003 has taken several forms. The Vietnam strain used to develop the vaccine in the Rochester trial is different from the strain that has killed some of the Indonesian victims of the disease.
Ultimately, the research will better inform policy decisions, such as whether first responders – medical, emergency and law enforcement – should be given a primer vaccine even before a pandemic emerges. Such a decision could be controversial because similar policy decisions in the past have led to resistance and apprehension among the targeted groups.
Limited vaccine production capacity is another problem that could impede a wide-scale preventive vaccination campaign.
The pandemic preparedness strategy announced by the Bush administration in 2005 acknowledged a diminished capacity for rapid production of vaccines in the United States and proposed various remedial steps that are still unfolding. (See related article.)
OTHER PREVENTION STRATEGIES
Vaccine development and emergency inoculation procedures are but two of many strategies under consideration in the national pandemic preparedness plan. The U.S. Centers for Disease Control and Prevention (CDC) is pursuing “community strategies” that might help curtail the spread of a pandemic, and reduce the rate of illness and death.
In fact, strategies that do not involve drugs or vaccines may be the first line of defense to slow the spread of disease, according to the October 10 news release from CDC.
“While we can't predict the severity of an influenza pandemic before it begins, our ability to effectively respond will depend on how well communities and states can take steps to reduce spread of disease," said CDC Director Dr. Julie Gerberding. "Our challenge now is to determine which community-level measures will work best to limit the spread of infection."
CDC is investing more than $5 million in research projects designed to see which community strategies are most effective. It is an international effort with two of the eight projects awarded to research teams at the University of Hong Kong and the University of Otago in New Zealand.
Community prevention strategies rely on influencing public behaviors in ways that will protect people from getting sick, or reduce contact between them so there are fewer opportunities for infected people to spread illness to others.
Public health information campaigns might remind people about proper hand washing and cough etiquette to prevent the spread of viruses.
“Social distancing” strategies involve reducing contact with other people including closing schools, workplaces or other gathering places such as theaters and shopping malls.
For ongoing coverage, see Bird Flu (Avian Influenza).
The NIAID press release is available on the institute’s Web site. The CDC press release is available on its Web site.
(The Washington File is a product of the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)
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