Sterility problems cited in flu vaccine delay

Supplies expected to be fine if problem resolved 

Word that a portion of the 2004-2005 influenza vaccine will be not available until later in the season poses no immediate health crisis, but underscores the vulnerable nature of vaccine production and distribution in the shadow of a pandemic.

Citing sterility problems during the production process, Chiron Corp. in the United Kingdom announced that it would delay delivery of its doses to the United States.

"The information we have from Chiron is that only a small proportion of the lots of vaccine that they have produced so far have been affected by the sterility problem," Julie Gerberding, MD, MPH, director of the Centers for Disease Control and Prevention (CDC) said at a press conference.

"They’re holding all of the lots until they get to the bottom of the problem. . . .They’re fixing it, and they’re just taking extra steps to be absolutely sure they’ve got a safe product before they deliver it for use in humans," she said.

Chiron has about half of the market share for flu vaccine; and the other manufacturer, Aventis Inc., is predicting on-time delivery of its doses of vaccine, Gerberding explained.

"So we will certainly have a significant supply ready at the beginning of the season to get started," she said. "This is not a crisis. This is just important information; and we wanted to give people the best information we could about what to expect so that we didn’t have a panic or we didn’t have people deferring vaccination who really need to get it."

Aventis is planning to fulfill its commitment to the people who had already ordered vaccine and then offer supplies to those places that still are waiting for Chiron, Gerberding added.

"Both manufacturers of the flu vaccine, as well as the people who make FluMist, which is the nasal vaccine, are working very closely with CDC and FDA [Food and Drug Administration] to try to assure a continuous supply of vaccine in places where it’s needed the most," she said.

With the possibility of pandemic influenza being widely discussed, the production glitch was viewed by some as the kind of problem that could crop up in the future when the stakes are higher. "The flu vaccine that we’re talking about this fall will target the flu strains that we know from our [surveillance] are circulating in the world right now," Gerberding added.

"None of these strains at this moment indicate a potential for pandemic development. But of course, anything can happen. And we remain very vigilant for the early identification of a pandemic strain," she explained.

About 100 million doses of flu vaccine are projected for distribution this year in the United States, which would be an insufficient supply to deal with a pandemic strain that by definition would face no natural immunity in the human population. However, the annual flu vaccine typically contains three killed influenza viruses.

"The [current] vaccine actually is three vaccines," she said. "If we were dealing with a pandemic and we were focusing on one product, we might be able to have more absolute doses because we wouldn’t be doing the same thing three times. Nevertheless, in the context of a global outbreak of influenza, right now, we don’t have enough capacity to reliably create all the vaccine that we could need in that situation."

Delay may hurt vaccination rates

Given the cited sterility problems at Chiron, there is some concern that the vaccine — already somewhat undermined by myths and misconceptions — might be viewed with suspicion and underutilized this year.

"I would emphasize that flu is a serious disease; 36,000 people, on average, die even in a year that is not a pandemic in this country. Last year, 152 children under the age of 18 died from influenza," Gerberding continued.

"I think that is a very ominous statistic and a very heart-wrenching situation for the families who were affected by that loss. Flu is something that is preventable and certainly the complications of flu, even among children, can be reduced by immunization. So nothing about the announcement from Chiron or the status of our current vaccination program should discourage parents, especially those parents of children between the ages of 6 months and 23 months, from receiving the flu vaccine. It’s lifesaving, and we strongly encourage people to get the facts they need to make an informed decision and get the kids vaccinated," she said.

Also indicated for routine flu vaccination are people older than 50, those with chronic medical conditions that weaken their immune system, women who expect to be pregnant during flu season, and health care workers.

"It’s very important that health care workers plan on getting the flu vaccine for their sake as well as their patients’ and their family’s sake," added Gerberding. "In addition, household contacts or other close contacts [of] those people who are at high risk for flu complications should receive the vaccine. Now [all] those people will be able to get their vaccine if the manufacturer’s projections are correct."