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A study led by a pediatric research team at the University of Maryland School of Medicine shows the value of vaccinating school-age children with FluMist, a nasal spray influenza vaccine that delivers a live but weakened vaccine to the nose. The study found that families of school children who received FluMist during an in-school immunization program experienced a significant drop in several common medical and economic consequences from the flu.
For example, the study found a 72 percent reduction in lost workdays for parents. In addition, the use of prescription drugs, herbal medicines and over-the-counter flu remedies dropped by more than 50 percent. The results of this study were presented during the Annual Conference on Vaccine Research of the National Foundation for Infectious Disease on May 25, 2004, in Arlington, Va.
"I never expected such a tremendous impact on the families," says lead investigator James C. King, Jr., MD, a pediatrician at the University of Maryland Medical Center and professor of pediatrics at the University of Maryland School of Medicine. "But it all makes biologic sense. Children are most susceptible to influenza, carry and spread the influenza virus over a longer period of time than adults, and are often the first to get the infection in the community. So if you stop flu in school kids, you might reduce its impact in the community. And that's what we saw."
Thirty-nine percent of the students at Elmer A. Wolfe Elementary School in Union Bridge, Md., were vaccinated in school from Nov. 4, 2003, to Jan. 14, 2004. A total of 185 students from age 5 to 12 received FluMist.
At the same time, researchers conducted community surveillance to detect the influenza outbreak period, which was defined as the point at which 90 percent of tests for influenza were detected as positive. The outbreak occurred between Dec. 1, 2003, and Jan. 5, 2004, peaking at about December 15.
To gauge the effect of FluMist, investigators distributed questionnaires to parents at Elmer Wolfe Elementary and compared their responses to questionnaires distributed in two demographically similar schools nearby without an in-school vaccination program. The questionnaires were distributed during the week of peak outbreak and asked parents to record medical and economic outcomes related to flu-like illness over the previous seven days.
Compared to the two schools where children were not vaccinated with FluMist, Elmer Wolfe families indicated a 72 percent drop in adult workdays lost, and a 46 percent drop in school days lost by all children in the family. There was also a 67 percent reduction in medical visits for adults, and a 60 percent decline for children. The use of medications went down in these families as well, with 56 percent less use of non-prescription drugs, a 59 percent drop in herbal/natural remedies and a 59 percent decrease in prescription drugs.
School absenteeism among FluMist recipients trended 4.4 percent lower than non-FluMist recipients, but overall, the researchers noted no statistical difference in absenteeism among the three study schools. While the researchers had hoped absenteeism would be lower at Elmer Wolfe Elementary, King points out that 61 percent of the students at the school were susceptible to flu because they had not been vaccinated with FluMist. "We don't think that 39 percent vaccination is enough protection to provide what we call `herd immunity' to affect absenteeism," says King.
The study will be expanded in the fall. Students will receive FluMist during in-school vaccination programs in cities in four geographically diverse areas: St. Cloud, Minn.; Seattle, Washington; Houston, Texas; and three schools in Carroll County, Maryland. King says the idea is to get a broad representation of how the nasal vaccine works in schools and to account for the possibility that influenza may not be prominent in all parts of the country every year. "If flu doesn't hit hard in Maryland, maybe we'll see it in Minnesota," says King
Another aspect of the study has important offshoots for vaccine research, according to King. "Even more striking than the benefits of the nasal spray vaccine in families is the fact that the immunization program essentially coincided with the outbreak of flu in the community and was still effective," he says. It usually takes about two weeks following flu vaccination to build immunity to the virus.
King says FluMist's effectiveness may be related to the fact that the nasal vaccine is a live form of the same virus used in the flu shot, and may offer broader protection. He notes that FluMist worked well in a year when the flu shot was not as effective. He says both are very important vaccines. "We obviously need the shot for people with weakened immune systems and patients who have chronic conditions, such as lung disease," says King. But he says there is some evidence from another FluMist study that in the week or two after vaccination, respiratory infections of all kinds were reduced in children. "Perhaps this nasal spray vaccine is just sort of revving up their immune system in a non-specific way," says King. "That may have happened in this study, but it would not happen with a shot."
The performance of FluMist may have implications for health officials who are keeping tabs on influenza outbreaks around the world, accord to King. In the event of an unanticipated viral outbreak, vaccinating with a nasal spray may offer rapid protection. "It seems to me that even if we get a late start on developing a vaccine and we can't manufacture the vaccine quickly, or well in advance of its arrival, you would still have a chance to have an impact right in the midst of the outbreak. That, to me, is a very exciting finding," says King.
This school-based FluMist study relied on a research methodology that the same team developed during a two-year study of schools in Carroll and Howard counties in Maryland, beginning in 2000. That study demonstrated a way to calculate the impact of a flu outbreak on absenteeism and predict the effect of universal vaccination in school-age children. The results of that study were presented May 4, 2004, at the Pediatric Academic Societies' Annual Meeting in San Francisco.
MedImmune Inc., the maker of FluMist, funded both studies.