CDC: Expect delays in flu vaccine distribution
CDC: Expect delays in flu vaccine distribution
While flu experts were hopeful that vaccine delays and shortages would not recur this year, the Centers for Disease Control and Prevention in Atlanta is reporting that preliminary information from manufacturers suggests that more influenza vaccine will be available this year than last year, but delays in the distribution of the vaccine will occur.
Projected distribution of influenza vaccine for 2001, based on aggregate manufacturers’ estimates as of June 15, is 83.7 million doses, which would exceed actual distribution in 1999 and 2000. In addition, 53.5 million doses are projected to be available by the end of October 2001, which is twice the amount, 26.6 million doses, available at the same time last year. However, in comparison to 1999, when there was no delay, 75.8 million or 99% of the total vaccine for the 1999 season was available by the end of October. In November and December of 2001, another 30.2 million doses (36%) of the total 83.7 million are projected to be available.
The CDC and the Food and Drug Administration (FDA) stress that these are early projections from manufacturers and could change as the season progresses. The CDC is recommending that health care facilities and other vaccine providers maintain a contingency plan. Hospitals also should order their vaccine early, preferably in the spring or summer, says Carolyn Buxton Bridges, MD, a medical epidemiologist in the influenza branch of the CDC. "It appeared that providers who ordered late in the season — September, October, or November — may have had a more difficult time getting vaccine in a timely manner."
There are now just three manufacturers of vaccine, as opposed to four in previous years, Bridges notes. With a tight time frame between identifying the strains and producing vaccine, the potential for delays always exists, she says. "Last year really illustrated the fragility of influenza vaccine supply," Bridges says. "For some people this came as a surprise. But in any year, there can be potential problems with influenza vaccine supplies because of the nature of [the development process]. There are a number of steps that have to occur in a timely manner each and every year. If any problem occurs in any step, it can throw off the timing of the vaccine and its availability."
As it turns out, the last flu season was a mild one that peaked from mid-January to early February. It was the first season since 1995-96 that was not predominated by A (H3N2) viruses, the CDC reported.1 "We usually see milder disease when influenza B and A (H1N1) viruses are "predominating," says Bridges.
For the 2001-2002 flu vaccine, the FDA’s Vaccines and Related Biological Products Advisory Committee recommended that a trivalent vaccine containing "A/New Caledonia/20/ 99-like (H1N1), A/Moscow/10/99-like (H3N2), and B/Sichuan/3 79/99-like viruses," the CDC reported.
The CDC has extended its recommendation for the optimal timing of vaccination from October to the end of November. (Previous recommendations were for October to mid-November.) However, the CDC advises hospitals and other providers to vaccinate high-risk persons and health care workers throughout the flu season, says Bridges. "It takes two weeks to develop peak antibody response after getting vaccinated, but people start to develop antibody within two days. There was some success last year to get providers to continue vaccinating."
It is too early to know the impact of last year’s vaccine delay on immunization trends, she says. And she urges providers not to become complacent after a milder season. "We have no way to predict if we’re going to have a mild or severe year [this year]," Bridges says. "We also cannot predict the timing either. The best thing is to always be prepared for a severe season."
[Editor’s note: For more information on influenza vaccination, see the CDC web site, www.cdc.gov.]
Reference
1. Centers for Disease Control and Prevention. Update: Influenza Activity —- United States and Worldwide, 2000 —01 Season, and Composition of the 2001 — 02 Influenza Vaccine. MMWR 2001; 50:466-470.
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