Flu vaccine production has been a research topic of some interest over the last several years. Broadly speaking this work has two prongs. One regards the challenges of production planning when yields are highly uncertain. The other deals with how to dole out the vaccine when supplies are limited. Some recent articles show that these are very practical questions. From today’s Wall Street Journal, we have a report that shipments of the H1N1 vaccine have fallen way short of forecasts (Vaccine Output Falls Short, Oct 24, 2009).
By Friday, 16.1 million doses of vaccine for what is also called H1N1 flu had been shipped to warehouses, the CDC said.
The total is far below the government’s most recent estimate that by the end of this month, about 28 million to 30 million doses would be ready.
That estimate itself is a revison, made last week, from a prior expectation of about 40 million doses by the end of the month. However, the number of doses shipped is steadily increasing.
The culprit here is the production process. Flu vaccine production involves growing the vaccine in chicken eggs (yes, eggs) which is time consuming and at some stages manually intensive. Hence, yields are uncertain. In the case of the swine flu vaccine, Novartis is yielding just one fifth of what they expected. But poor yields are not the only issue. MedImmune makes a nasally inhaled version of the vaccine and has had better luck in making the serum. They, however, are limited by the number of sprayers they can get their hands on.
But swine flu is not the only flu in town. My family spent an undue amount of time last weekend trying to find a pharmacy or clinic that both had the seasonal flu vaccine and was willing to inject it into an eight year old. Turns out that the seasonal flu vaccine is also in short supply (You want a regular flu shot? Get in line. Marketplace Morning Report, Oct 22). The swine flu is partly to blame. Firms have limited capacity and many have signed up to produce the H1N1 vaccine. Also, apparently vaccine makers got burned last year:
Last year about 135 million doses were produced, but only about 113 million doses were actually distributed.
That has left them short given a surge in demand this year. Then there is the question of distribution. In Chicago, many physicians offices have run out the vaccine before the local pharmacies (Flu vaccines get scarcer in Chicago-area doctors’ offices, Chicago Tribune, Oct 15). The likes of Wallgreens and CVS claim that they ordered more this year and have been willing to transship vaccine between stores. Physician groups, however, have reported that they have not received their full shipments. It doesn’t seem that the big pharmacies getting rich on giving flu shots. The wholesale price on the seasonal flu vaccine is supposedly around $15 per dose (Flu boosts vaccine business, Chicago Tribune, Oct 19) but the pharmacies have been charging around $25.
Finally, let me note that an article in the current issue of The Atlantic that questions whether the vaccine is worth the effort (Does the Vaccine Matter?, Nov 2009)
UPDATE: Here are two more article following up on the difficulties of making influenza vaccines: A Nation Battling Swine Flu, and Short Vaccine Supplies, New York Times, Oct 26 and Swine Flu Vaccine Shortage: Why?, Morning Edition, Oct 26. The latter gives the following:
Officials at the Centers for Disease Control and Prevention say for months, the companies didn’t realize how far short their vaccine “yields” were falling. That’s because they didn’t have the chemicals — called reagents — that would have told them how much active ingredient they had in their vaccine production vats.
“To really understand how much product you have, you need to do potency tests,” says Dr. Anne Schuchat, chief of the CDC’s National Center for Immunization and Respiratory Diseases. She says reliable tests used to measure potency were delayed.
“When they were run, the manufacturers basically found out that the product they had was actually less than they thought they had,” Schuchat said in an interview with NPR. “That wasn’t something we knew a long time ago. That’s relatively recent.”
According to the Times, some argue that the government has just overly optimistic all along about what they would get from the production process:
To my mind, it was over-promising what there would be based on our historic experience with flu vaccines,” said Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
“When you plant corn in May in Iowa, you have no idea what your harvest is going to be in October,” Dr. Osterholm said. “You have to factor in hailstorms, floods and whatever. They put out a very high yield estimate early on. Every time they had to back off, they lost credibility.”
Federal officials say they factored such difficulties into their projections. They say they were pressed to make the projections by state and local health officials and by the news media.