Wednesday, August 27, 2008

Is FDA Interested in the Safety of Anthrax Vaccine?

FDA answered a Freedom of Information Act request for me today. I asked how many adverse event reports had been filed for anthrax vaccine (5,931 reports through July 22, 2008) and how many FDA had designated as SERIOUS (618 reports). Serious reports are those indicating an event requiring hospitalization, a life-threatening event, permanent disability, or loss of life.

I further asked whether FDA has performed any studies to assess causality (i.e., were adverse outcomes a result of the vaccination?) or if FDA has required the manufacturer to do so. The answer was 'No' to both questions.

FDA referred me to CDC. CDC began a clinical trial of anthrax vaccine in 1,564 people in 2002. Subjects were enrolled for 43 months, which theoretically should yield excellent long-term data. But no report from the study has been made public, despite early promises that a preliminary report would be released in 2004, and a final report in 2007.

The CDC's Advisory Committee on Immunization Practices met February 27-28, 2008 and discussed anthrax vaccine and this trial. Slides from every talk except the anthrax vaccine talks were posted by the CDC here. But the slides from each of the 4 talks on anthrax vaccine are listed as "coming soon."

However, I did manage to find this tidbit (see page 155 of the report): in CDC's clinical trial of 1,564 subjects, there were 229 reports of serious adverse events! That means, if you entered the anthrax vaccine trial, you had a greater than 1 in 7 chance of suffering a serious adverse event within the next 43 months. Yet despite failing to cite quantitative data, CDC thought the vast majority of serious events were not related to the vaccine. (But something bad was happening to this cohort of subjects, about 85% of whom received anthrax vaccine.)

Over 2 million people have received more than 7.5 million doses of the Bioport (now Emergent BioSolutions/EBS) anthrax vaccine since 1998, and all deploying soldiers and most contractors must be vaccinated as a condition of employment. Yet no federal public health agency is anxious to release definitive safety/injury data. Wonder why?

4 comments:

spoonful said...

These statistics are quite informative. I wonder, however, what would be the breakdown of the 2MM people receiving 7.5mm vaccine doses for the pre and post 9/11 periods.

Meryl Nass, M.D. said...

Over the past ten years, the rate of adverse events reports to FDA has ranged from one in 250 to one in 350 vaccine recipients. It was the same before and after the rebuilt vaccine facility came online in January 2002.

The rate of vaccinations per person has held steady at 3.9 vaccines per person, suggesting that the average person receives 3 initial doses in 4 weeks and the 6-month booster, then stops.

What has varied widely over time are the number and percentage of reports FDA designated as SERIOUS, compared to the total number of reports.

For example, last year FDA informed me that the total number of SERIOUS adverse event reports as of June 6, 2007 was 670. Thirteen months later, with total reports about 10% higher, the number designated serious has FALLEN to 617.

These numbers have jumped around, with the percentage of serious reports ranging from 5% to 15% or more at different times. The only explanation is that FDA has gone through the list and reclassified reports from time to time.

When the vaccine was under greater scrutiny, a favored DOD response to the high overall reporting rate (highest for any licensed vaccine both per dose and per person vaccinated) was to claim that the reports were of mainly minor illnesses.

The CDC trial, however, yielded a disproportionately high rate of serious adverse event reports. A review of the trial's raw data will be illuminating.

Meryl Nass

Meryl Nass, M.D. said...

Oh, I forgot. The number of reported deaths has also dropped. It was 44 in June 2007. But at an ACIP meeting in February, Col. Cieslak claimed that as of November 2007, only 25 deaths had been reported.

An FDA IG report may be needed to sort out this statistical goulash.

Meryl Nass, MD

Fda Pharmaceutical said...

Good post......