H1N1 Vaccine Shortage: Blame Chickens

A major rate-limiting step in the production of the 2009 H1N1 vaccine is limited chicken eggs—at least according to the AP. So far, federally contracted companies have only been able to churn out about 10% of the promised 120 million doses for US residents, mostly because of a shortage of fertilized hens' eggs, which are required for viral cultivation. As a result, the vaccine is being restricted to the highest priority candidates.

In addition, the 2009 H1N1 strain appears to be more fastidious than typical seasonal influenza viruses, requiring 2 eggs instead of the usual one to produce a single vaccine dose. Therefore 240 million eggs are needed to make 120 million vaccine doses. According to Commercial Chicken Meat and Egg Production (only $279.20 at Amazon), 1 chicken can pound out about 300 eggs annually.* If so, 800,000 chickens can produce the required number of eggs for the US supply of the 2009 H1N1 vaccine in 1 year. The AP reports that more than 30 US farms, representing 9-12 million chickens, are under long-term contract to provide eggs for vaccine production.

Alternative methods for viral cultivation, including growth in mammalian or insect cells, are evidently being explored by industry through multimillion-dollar federal contracts.

* Dunno if the rate applies equally to unfertilized and fertilized eggs.