EGGS VERSUS CELLS
Despite the perennial risk of contaminated cell cultures, there's a big push underway to switch influenza vaccine production
from eggs to cellular methods. The campaign accelerated after vaccine makers failed to deliver some 100 million doses of the
new H1N1 influenza last summer as expected; industry and government officials lost considerable credibility when only 40 million
doses were available in September, and some 20 million Americans already were hit by the new flu. Health and Human Services
(HHS) Secretary Kathleen Sebelius said she relied on industry predictions that turned out to be wildly overoptimistic, although
manufacturers claimed they kept health officials informed of their technical problems.
Manufacturers have used fertile chicken eggs to grow flu vaccine since the 1930s, because the influenza virus grows well in
eggs, an important feature for fast production of a viral strain that changes every year. But with the H1N1 flu, production
took longer than expected because the yield in each egg was much lower than with seasonal flu viral strains. The resulting
delays have prompted government officials and manufacturers to accelerate the shift to cell-culture flu vaccine production.
Such methods have been used for decades to produce vaccines for mumps, measles, polio, rubella, and other diseases, explained
Jesse Goodman, FDA chief scientist, at a December 2009 seminar on advances in influenza vaccine technologies at the National
Institutes of Health (NIH). But that approach has not been adopted for influenza because it can take a long time to get a
good yield out of cell cultures.
The change will not transform influenza flu vaccine production, said Goodman, but could lead to more reliable products and
faster scale-up. Anthony Fauci, director of NIH's National Institute of Allergy and Infectious Diseases, agreed that shifting
to cell culture doesn't cut off that much production time, but could establish a more flexible surge capacity. Making the
transition from egg- to cell-based production "will take some time," Fauci said, "but eventually we will get there."
Support for this transition comes from HHS' Biomedical Advanced Research & Development Authority (BARDA), which funds efforts
to expand manufacturing capacity for influenza vaccine as part of its mission to expand research and production of public
health countermeasures. BARDA has awarded grants and contracts to construct new facilities and retrofit existing plants with
an eye to creating more robust, flexible, and scalable manufacturing systems, explained BARDA Director Robin Robinson at the
NIH seminar. A big winner is Novartis, which received $487 million (of $1.3 billion in grants to manufacturers) to construct
a cell-based pandemic and seasonal flu vaccine manufacturing facility; the new plant opened a few months ago and is scheduled
to be operational in 2011.
Potency has been another issue with H1N1 vaccine production. Even though clinical trials indicated that the new vaccine was
effective with a single dose in adults, manufacturers found some lots inadequate: Astra-Zeneca's MedImmune had to recall nearly
5 million doses of its nasal spray vaccine in December, and Sanofi Aventis pulled 800,000 doses in prefilled syringes for
young children. But by then, the pandemic was ebbing, and manufacturers faced a new problem: more vaccine than anyone wanted.
Last month, the French government moved to sell off millions of doses to countries in the Middle East and Latin America, and
to cancel sizeable orders from Sanofi, Glaxo, Novartis, and Baxter.
The real "endgame answer" to pandemic and seasonal flu vaccine production problems, according to Fauci, is to develop a universal
influenza vaccine that could be administered in childhood and last a lifetime, as with most vaccines against infectious disease.
Such a discovery could reduce the need to produce 120–150 million doses of a new influenza vaccine each year in the US, at
a cost of $2.8–4 billion. "And it is doable," Fauci said, noting that researchers already are identifying possible vaccine
targets that don't change with every different influenza virus.
Even though the FDA received some of the blame for the pandemic flu vaccine manufacturing woes last fall, Commissioner Margaret
Hamburg prefers to regard the response from the FDA and from the industry as "quite remarkable in terms of how much has been
mobilized in response to a previously unrecognized strain of flu virus." Some of the disappointment may stem from over-optimism
in predicting how much vaccine would be available when. "Sadly, we know that it's the nature of manufacturing vaccines to
have some unexpected delays, and it's the nature of science to have unanticipated problems emerge."
Jill Wechsler is BioPharm International's Washington editor, Chevy Chase, MD, 301.656.4634, email@example.com