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Lessons from H1N1 (Swine Flu)

After public health authorities in the United States spent months encouraging, cajoling, and frightening the public into getting vaccinated against the H1N1 influenza virus, they had no vaccine to give. The second wave of the H1N1 pandemic hit North America in early fall 2009. Millions were infected and thousands died before people were immunized. Of the 250 million doses of vaccine ordered by the U.S. government, only five million had been delivered at the height of the outbreak because of problems with vaccine production.

Flu vaccines are manufactured using a half-century-old process in which live virus is injected into 11-day-old embryonated chicken eggs. Once a virus is isolated and identified, it is incubated in eggs, extracted, attenuated, refined into vaccine, and then tested for safety and efficacy. It’s a process that, if all goes well, takes up to six months. Add to this the need to pre-order hundreds of millions of fertilized eggs many months in advance, problems with contamination and infection that can cause entire batches of vaccine to be lost, and the small output (about two doses per egg), and it is evident that egg-based flu vaccine production will never outrun a major, fast-moving pandemic such as H1N1. A paper published last fall in Eurosurveillance predicted as much, showing that the second wave of H1N1 infections would peak in the U.S. before the CDC’s planned vaccination program could have a significant effect.

As the H1N1 flu pandemic demonstrated, delays in vaccine availability are very costly: in productive work days lost, school days missed, and in preventable hospitalizations that strain the health care system. When H1N1 vaccines were finally available – though still in short supply – people spent hours in line waiting for shots, resulting in countless more lost work and school hours. The economic costs, however, pale in comparison to the toll in lost lives. CDC estimatesof H1N1 infections, hospitalizations, and deaths between April and December reveal the real price of vaccine delays: 39 million to 80 million infections, 173,000 to 362,000 hospitalizations, and 7,880 to 16,460 deaths.

It is a foundational truth of public health that vaccines save lives, and that public immunization campaigns are worthwhile expenditures. Governments around the world responded appropriately and rapidly after the initial outbreak of H1N1 last spring: the virus was quickly identified, and huge numbers of vaccines were ordered. A plan was hatched: mass vaccinations to prevent the next outbreak of H1N1 flu.

What happened next, however, revealed the cracks in the system: vaccine manufacturers made delivery promises they couldn’t keep when H1N1 proved to be a slow-growing virus. The government failed in its oversight of the private pharmaceutical companies it had contracted with to manufacture vaccine, and continued to tell the public that vaccines were coming when it was clear they were not. Everybody had egg on their faces.

There are other problems with egg-based vaccines: an estimated one to two percent of the population is allergic to eggs and cannot receive egg-based vaccines; there are concerns about animal welfare related to large-scale egg production; and egg-based vaccine culture requires the use of live virus, which is a danger when working with particularly potent strains of influenza. H5N1 (“Avian”) flu is a likely candidate for a future pandemic, but because the H5N1 virus is lethal to both chickens and eggs, that vaccine cannot be grown in eggs.

The challenge is to find better, faster, egg-free methods of producing vaccines. Researchers have already developed and tested several promising alternatives, using insect cell cultures, bioreactors, and recombinant DNA cell cultures (utilizing immortal cell lines), which have the potential to be faster and more reliable. Some of the resulting vaccines have already undergone clinical trials and demonstrated safety and effectiveness.

Licensed vaccines for hepatitis B and human papillomavirus are produced using recombinant DNA techniques. There are several cell culture-based flu vaccines licensed in Europe and used throughout the E.U., including an approved vaccine against H1N1 flu. (By contrast, a Food and Drug Administration advisory panel narrowly rejected accelerated approval for the U.S.’s first cell-based seasonal flu vaccine in November 2009, citing a lack of safety information for persons over 65. (Documents released by the FDA asserted that the vaccine was as safe and effective as other flu vaccines in four human trials of 3,231 adults. Although one third of trial participants were over 65, the FDA concluded that the number of cases was too small to assess the vaccine’s safety.)

The alternative methods have the benefit of being more flexible than the egg-based method, allowing production to be scaled up rapidly to respond to emergent pandemic threats. It might also be possible to mount “prepandemic vaccination” programs, to prime population immunity to likely diseases (H5N1 flu, for example) years ahead of critical need. Such a plan has already been tested in the U.K.

What’s preventing the adoption of better methods of vaccine production? One factor is cost. Several vaccine manufacturers have ceased producing flu vaccine altogether because it isn’t profitable. The few remaining vaccine manufacturers – major multinational pharmaceutical companies – have little financial incentive to build the expensive facilities needed to produce new vaccines on a mass scale, especially if governments continue to pay for vaccines produced the old fashioned way. To date, only a single large-scale facility has broken ground in the U.S. – the Novartis cell-culture facility in North Carolina, which is years away from mass-producing vaccine.

This is not a problem that will be solved by private industry or the whims of the marketplace. It will require government funding, and government control over vaccine production. Yet this is not a man-on-the-moon effort. The technology to achieve meaningful results is well within our grasp right now. Developing a more responsive and flexible vaccine manufacturing system should be a public health priority for countries in the developed world capable of initiating such a program. It is not something we can afford to put off; it is a necessity that cannot be delayed without endangering many lives.

The influenza pandemic of 1918 killed 40 million people worldwide. Today, virulent flu strains can travel the world faster, along with their human hosts. Advances in critical care medicine make it unlikely that another pandemic would have the same toll in human lives, at least not in parts of the world where there is ready access to critical care hospitals, but the economic and human costs of a major outbreak of flu would still be considerable, especially in the developing world. Prevention is therefore critical. Another pandemic is inevitable, and the lesson of H1N1 is now clear: we are not ready.

L. Syd M. Johnson, Ph.D., research fellow in neuroethics at Novel Tech Ethics, Dalhousie University.

Published on: February 3, 2010
Published in: Health and Health Care

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