RSS
Home
Why is it taking so long to get the flu vaccine?
Print
Email
RSS
Subscribe
AP Photo/Tony Dejak
Local media nationwide have been reporting the cancellation of seasonal flu vaccine clinics as well as the limited availability of vaccine for the Swine Flu. The limited number of doses of vaccine for both types of influenza is due to several factors.
Dr. Ann Schuchat, the director of the National Center for Immunization and Respiratory Diseases, spoke to reporters on October 13. Several of the questions related to the short supply of seasonal influenza vaccine and the distribution of the Swine Flu vaccine. 77 million doses of seasonal vaccine have been distributed and nearly 10 million doses of Swine Flu vaccine were available for order.
The first pandemic H1N1 vaccine to ship were doses of live attenuated intranasal vaccine (LAIV). This vaccine is designed for patients between the ages of 2 and 49 who are in good health and not pregnant. The injected vaccine for Swine Flu is now shipping and is intended for all patients over the age of 6 months.
The production cycle for an influenza vaccine begins with the public health authorities such as the Centers for Disease Control (CDC) or the World Health Organization (WHO) identifying the viral strains that will be included in the vaccine. Season flu strains are identified about six months before production of a vaccine begins.
Production of season flu vaccine was well underway when the Swine Flu outbreak began in April 2009. When the various authorities requested the development of a vaccine in May, the manufacturers were faced with some issues.
Nearly all flu vaccines begin with supplies of the virus grown in chicken eggs. There are only so many chicken eggs, and egg production is not subject to a rapid increase in production. Vaccine manufacturers diverted some of their egg supplies to the Swine Flu vaccine, slowing but not stopping production of the seasonal flu vaccine.
UPDATE on 10-28-2009: According to Discover and Scientific American, the chicken eggs must be fertilized. Commercial egg producers do not normally sell fertilized eggs so the eggs in the supermarket are no good for vaccine production.
A number of manufacturers then discovered that their processes did not produce the viral materials as effectively as necessary. Changes in those processes added time to the production cycle.
In mid-summer of 2009, the LAIV became available in limited quantities. At this point in time, the CDC is receiving about equal numbers of doses for both types of Swine Flu vaccine. Schuchat expects that all orders for both the seasonal flu vaccine and the pandemic flu vaccine will be filled, though not as fast as anticipated.
The CDC has published a table showing the current doses supplied and shipped to the states and territories. Both flu vaccines take about two weeks to create an immunity. It is possible to contract the flu within that time window.
Concerns have been raised by some about two types of additives to vaccines.
Adjuvants are chemicals that are used to dilute the vaccine slightly to increase the supply without damaging its effectiveness. In Europe, some of the vaccines will contain squalene. None of the influenza vaccines used in the United States will contain any adjuvant.
Thimerosal is a chemical used in multi-dose vials of vaccine to prevent the growth of microorganisms, which would contaminate the vaccine. LAIV does not use this chemical. Single dose vials of the Swine Flu vaccine are being produced that will not use thimerosal, either.
The CDC expects that all orders for the seasonal flu vaccine and the Swine Flu vaccine will be filled by the manufacturers. The government requested that these companies send out the Swine Flu vaccine as it was packaged, resulting in smaller lots being shipped over a longer time period.
Any vaccine carries both risks and benefits. A physician will be able to supply information allowing patients to evaluate their need for a vaccine, or their children's needs.
- More articles about Pandemic Swine Flu
- CDC: Key Facts About 2009 H1N1 Flu Vaccine
Related Articles:
Comments
