H7N9 an early test for revised U.S. pandemic preparations
When scientists advising President Obama came to analyze the U.S. response to the outbreak of H1N1, they identified several major bottlenecks that needed clearing. Poor yields from seed viruses were near the top of the list, and the scientists set a two year target for improving.
Now, two and a half years after publication of the analysis, methods adopted in the wake of the report are being put to the test. In response to the spread of H7N9 in China--which at the time has killed 6--the Centers for Disease Control and Prevention (CDC) has begun vaccine preparation. This time, instead of waiting for a virus sample to ship from China, the CDC is using synthetic DNA.
Elimination of the shipping step is one time-saving element of the method, but the bigger gains are expected when the vaccine goes into production. In 2009, H1N1 seed strains reached manufacturers ahead of schedule, only for vaccine production to falter as optimization took weeks longer than expected. For the H7N9 seed strain the CDC is working with viral backbones that have delivered good yields in the past. Genetic information shared by China is being used to add the outer spikes to the backbone, customizing the pre-existing framework to H7N9. Novartis, the J. Craig Venter Institute and other organizations are collaborating with the government on the creation of the seed virus. Vaccine manufacturers should see the benefits of this work when seed virus optimization begins.
The method was proposed in the aforementioned Presidential report into the H1N1 outbreak and could knock weeks off vaccine production timelines. "If everything works smoothly the first time, we could theoretically have it ready to send to manufacturers within four weeks," CDC associate lab director Michael Shaw told The New York Times. The need to test the seed vaccine in ferrets limits how quickly the CDC can get materials to manufacturers.
With H7N9 causing increasing concern among health experts, CDC is keen to get preparations underway. One-third of all confirmed cases of H7N9 have resulted in death. And the genetics of the virus suggest it can mutate readily, which could lead to human-to-human transmission. To limit its spread Chinese authorities are culling birds at markets, but with poultry and pigeons seemingly carrying the virus without falling ill, keeping track of the disease is tough. A vaccine is on the way, but for now the antivirals Tamiflu and Relenza--both of which appear effective--are the only pharmaceutical lines of defense.
Special Report: Top 10 selling flu vaccines of 2012
Roche's Tamiflu, GSK's Relenza work against new bird flu strain
Adimmune, other vax makers alert to stealthy bird flu
Scientists demonstrate how bird flu could trigger a pandemic
Controversial bird flu study details revealed