Most Flu Shot Plans Do Not Address How To Vaccinate Hard-to-reach Populations

"Hard-to-reach populations are important to vaccinate not only because they're personally vulnerable, but because they could be widely transmitting disease to others," said lead author David Vlahov, PhD, Director of the Academy's Center for Urban Epidemiologic Studies (CUES) and Senior Vice President for Research. "The importance of achieving high flu immunization rates is magnified by concern over pandemic influenza."

Influenza vaccination will begin to be offered by some U.S. healthcare providers as early as next month in preparation for flu season, which usually extends from November through April of each year. Considerable attention will be devoted once again to achieving high levels of vaccination, since the vaccine is the best way to reduce one's chance of getting the flu, according to the U.S. Centers for Disease Control and Prevention. Influenza is a serious disease, causing 36,000 deaths (mostly among those aged 65 years or older) and striking 10 to 20 percent of the American population each year.

Most health departments' flu-shot recommendations address how to reach high-risk groups such as the elderly and those with chronic disease, but give less attention to covering HTR populations. Pandemic flu will spread faster if these large segments of the population are left unvaccinated, said Vlahov, who has been working under a $3 million National Institutes of Health grant to devise a plan for quickly finding and immunizing HTR groups. HTR populations in the United States are substantial, including as many as 12 million undocumented immigrants, 1.5 million injection drug users, and 744,000 homeless people, researchers note.

The health of HTR populations has broad implications for the health of the general public, Vlahov said. Some undocumented immigrants, for example, work in poultry processing, the food service industry, and in the home healthcare field, and homeless individuals often ride on subways and buses, coming in contact with large numbers of people.

The authors suggest several achievable strategies for increasing immunization coverage among HTR populations, including distributing vaccines in unconventional sites, such as needle-exchange programs and on street corners that are familiar locations to HTR people. The Academy's CUES in 2004 developed Project VIVA, or Venue-Intensive Vaccines for Adults, a small-scale rapid-vaccination approach. Project VIVA involved vaccinating people on busy sidewalks in Harlem and by going door-to-door in housing projects in the South Bronx. Bilingual outreach workers from the Academy working with licensed nurses gave the flu vaccine to over 1,000 homeless, homebound elderly, immigrants, minorities, and injection drug users in a 10-day period during the 2005-06 flu season.

Even within conventional sites for immunizations, the authors suggest several achievable strategies for increasing immunization coverage among HTR populations. Patient reminders, in the form of computer-automated mailings and autodial telephone messages, used for elderly patients in upstate New York have resulted in dramatic increases in vaccination rates in high-risk groups. In addition, more healthcare workers should be vaccinated against the flu. Only about one-third to one-half of healthcare workers are currently immunized, researchers note. "Providers who do not believe the vaccine is protective are less likely to recommend it to patients," Vlahov said.

"The current federal recommendations for annual and pandemic vaccine do not prioritize the issue of HTR populations," Vlahov said. "This problem is an epidemiologic, clinical, and ethical issue."

The study, entitled "Strategies for Improving Influenza Immunization Rates among Hard-to-Reach Populations," was based in part on a day-long meeting the Academy hosted in September 2006 on optimizing strategies to vaccinate HTR populations and on the findings of Project VIVA. Academy co-authors of the study are Danielle C. Ompad, PhD, and Sandro Galea, MD, DrPH. The other co-author is Micaela H. Coady, MS, of the city Department of Health and Mental Hygiene.