The Centers for Disease Control and Prevention (CDC) recently announced that influenza vaccine manufacturers expect to produce and distribute more than 100 million doses of influenza vaccine in the United States between now and early January 2007. Manufacturers have already begun to ship this season’s influenza vaccine, with almost all of the vaccine expected to be shipped and distributed in by the end of November. Influenza manufacturers and major distributors are implementing policies designed to supply some influenza vaccine to all providers who have ordered it.
“As we’ve learned in the past few years, there is always some uncertainty regarding influenza vaccine supplies and distribution,” says Julie Gerberding, MD, CDC director. “It’s often very difficult to predict how much vaccine will be distributed and when, or exactly when, influenza vaccine will be available for those who provide it. However, if the manufacturers' estimates hold, more people than ever before can protect themselves and their loved ones from influenza this year.”
—Julie Gerberding, MD
Influenza vaccine manufacturers’ estimate of more than 100 million doses is at least 17 million more doses of influenza vaccine than has ever been distributed in the past—the previous record was 83.1 million doses in 2003. The estimate exceeds the 81.2 million doses that were distributed last year by about 19 million. As of press time, about 75 million doses were expected to be distributed by the end of October; if that happens, it will be about 15 million more doses than were distributed by the end of October 2005.
“As our recommendations highlight, there are many people who can benefit from the protection an influenza vaccine can provide, especially healthcare providers, children between six months and … five years of age, people with chronic diseases such as diabetes, asthma, and heart disease, and people 50 years old and older,” says Dr. Gerberding. “Our goal, and the goal of those who provide influenza vaccine, is to use every available dose so that we protect as many people as possible.”
According to Lance Rodewald, MD, director of CDC’s Immunization Services Division, the CDC has been working with influenza vaccine manufacturers and distributors to monitor this season’s influenza vaccine supply and the timing of its distribution. In addition, the Food and Drug Administration (FDA) has successfully worked with vaccine manufacturers to increase both the supply and its diversity and to facilitate early availability.
“When and how much vaccine each healthcare provider or clinic receives depends on who they ordered from and when they ordered,” says Dr. Rodewald. “There are many manufacturers and distributors, each of which has different distribution plans and schedules. We expect that some healthcare providers and clinics may get or have more influenza vaccine than others in the first month or so, but people will have plenty of opportunities to be vaccinated during October and November, as well as December or later.”
While the best time for vaccination is in October and November (before the influenza season typically begins), vaccination can still provide protection in December and beyond because, during most years, influenza does not peak until February or later. Because influenza is unpredictable, and because different strains of influenza circulate throughout the flu season, the CDC’s Advisory Committee on Immunization Practices (ACIP) recommends that influenza vaccine be offered throughout the influenza season—even after influenza has appeared or has begun appearing in a community.
Each year in the United States, between 5%-20% of the population is infected with influenza; about 36,000 people die, and more than 200,000 people are hospitalized because of influenza complications.
Because influenza viruses are continuously changing, the strains of virus included in the influenza vaccine are reevaluated each year, and a new vaccine must be formulated for each season. The vaccine is typically made up of three viruses, including one influenza type B virus and two influenza type A virus strains, and each must be grown individually before the three are combined late in the production process. The strains are usually chosen in February, and the vaccine production and preparation process takes about six to eight months. Distribution of influenza vaccine begins as early as August and typically continues throughout November and December.
The viruses in the 2006-2007 influenza vaccine are:
- An A/New Caledonia/20/99 (H1N1)-like virus;
- An A/Wisconsin/67/2005 (H3N2)-like virus (A/Wisconsin/67/2005and A/Hiroshima/52/2005 strains); and
- AB/Malaysia/2506/2004-like virus (B/Malaysia/2506/2004 and B/Ohio/1/2005 strains)
For more information about influenza and influenza vaccine, visit www.cdc.gov/flu. TH