(Edit: For those interested in the toxic components of the vaccine please look here.)

Recently I  read a letter in a New Zealand paper decrying the widespread acceptance of the new HPV vaccine Gardasil. The letter contained references to suitably scary statistics from a impressive sounding report, in it it was claimed that Gardasil had contributed to the deaths of 18 people and had over 8000 reports of harm due to the administering of the vaccine. The letter ended with the sentence “This vaccine is essentially a large-scale, public health experiment. With doubt about its safety and efficacy, my daughters will not be getting it.”  I thought it might be useful to provide some information that casts a little more light on the situation, the statistics used in the letter and information on efficacy.

Background
If you are unaware Gardasil is the commercial name for a vaccine developed in the US that immunizes against 4 strains of human papillomavirus (HPV) that has be linked to both genital warts and cervical cancer. It has been marketed around the world as a preventative measure aimed at girls ideally before onset of sexual activity. Religious opposition to the vaccine has formed under the somewhat simplistic idea that as HPV is transmitted sexually then giving the vaccine somehow promotes promiscuity in girls. In a send-up of this line of thinking Stephen Colbert quipped “Curing a disease caused by a certain activity always makes you want to do more of that activity. I mean, once I got my tetanus shot I couldn’t stop chewing on rusty nails.”. Around 80% of the population are infected with one of the HPV strains, and while transmission is primarily by sexual means both vertical transmission from mother to child and from skin contact is possible.

Approximately 70% of cervical cancers and 90% of genital warts are caused* by the strains represented in the vaccine. It is estimated that in New Zealand there are 200 cases of cervical cancer a year, 70 of which end in death. Using these statistics we can easily show that a possible 50 deaths a year could be prevented in NZ alone. Now, any medical intervention has risks and vaccines are no exception. That said the risks of vaccines are vastly outweighed by the benefits, if this was not the case then the vaccine industry would very soon dry up and disappear as the effectiveness of vaccines is tracked long term by following the prevalence of the diseases they protect against in the population at large. In this way we can even see how reduction in vaccine adherence in particular locations correlates with outbreaks of the disease in those areas, for example the increase in measles outbreaks in the UK following the MMR vaccine controversy.

Harm
With the above in mind we can look at the reported adverse reactions, as of June 30 2007 there were 2531 adverse reports, including 9 deaths, out of 7 million doses dispensed, if we assume both that these reports are verifiably true and that were all caused by Gardasil then for the New Zealand population this equates to about 3 deaths. Now any preventable death should be held up as a failure of our society but shall we compare this to the current toll racked up by the target of the Gardasil vaccine? As stated above 50 lives could be saved each year by using the vaccine, this I think is a benefit that out weighs the risk.

For those of you interested in the US stats for 2008:
Estimated new cases of cervical (uterine cervix) cancer: 11,070; deaths: 3,870.

Adverse Events
The figures used to cast doubt on the safety of the Gardasil vaccine were taken from the Juducial Watch Special Report on Gardasil which in turn obtained the figures from the US Food and Drug Administration’s Vaccine Adverse Event Reporting System (VAERS). To quote from an article released on this subject focusing on the Canadian implementation of the vaccine:

“According to the Centers for Disease Control and Prevention in Atlanta, as of June 30 [2007], there were 2531 adverse reports, including 9 deaths, out of 7 million doses dispensed. The figures, however, can include multiple reports of the same event, since physicians, manufacturers and patients report to the same system.”

Also this register only meant to records events that happen in proximity in time to the vaccination and is not screened to prevent instances that are unrelated, in fact even obviously bogus entries will be accepted and dutifully recorded. For example one doctor reported that an influenza vaccine turned him into the Hulk, he eventually gave permission for the entry to be deleted but had he not it would still be there. Thus this data should be looked at as a source of possible adverse reactions but each report should be looked at closely to determine if it represents a real reaction. As the only requirement is that events follow closely after the administering of the vaccine then any coincidence can be recorded, given the extremely large numbers of vaccine doses dispensed (three per person, giving multiple chances for coincidences for each girl) then it is the lack of coincidences that would be truly remarkable.

VAERS is able to be used by anyone to report any symptom related to vaccines this subjects the database to biasing influences such as publicity increasing the amount of scrutiny that recipients of vaccines are placed under. In addition this makes it susceptible to the same event being multiply reported by both different health authorities as well as the general public.

The 9 deaths that were reported to the VAERS system up until June 2008 were looked at closely to determine the cause of each death. Of the nine there were four actual deaths confirmed, several were duplicate reports and one girl turned out to still be alive. The four remaining death reports consisted of 2 women who died after suffering pulmonary embolisms and two girls who had influenza of which one died from myocarditis. The two women who suffered pulmonary embolisms were also taking birth control pills which is a known risk factor. In the end none of the deaths could be shown to be caused or even influenced by the Gardasil vaccine.

Adverse events continue to be recorded and according to the CDC website as of June 30, 2008, 20 deaths had been reported to VAERS. The vaccine safety statement on the website concluded that: “There was not a common pattern to the deaths that would suggest they were caused by the vaccine. In cases where autopsy, death certificate and medical records were available, the cause of death was explained by factors other than the vaccine.”

Long-term Safety and Efficacy
The safety and efficacy of vaccines is not a single one off issue that is studied once and dismissed, the argument that there are still factors that may influence the associated risks of vaccines that will only be apparent after years of exposure is serious and is also being investigated. To this end long-term studies are being conducted in Scandinavia that will go on for at least 10 years.

However while these long-term studies will provide useful information there was not a paucity of data before the vaccine was introduced for commercial distribution. The efficacy of Gardasil was demonstrated in 4 large, randomized, phase II and III studies that enrolled a total of 20,541 women aged 16 to 26. The end point measured by the studies was the development of pre-cancerous lesions and the vaccine provided efficacy approaching 99% protection in girls who had not previously been exposed to the HPV strains covered by the vaccine and a modest protection factor (close to 45%) in those that were already exposed.

Conclusion
In the final analysis there seem to me to be considerable benefits to the vaccine and that there seem to be no significant drawbacks. Scaremongering aside there seems to be no reason to withhold the vaccine from girls who have yet to be exposed to the HPV strains most likely to cause cancer. While I mentioned above that religious opposition had been raised against the vaccine even this looks to be fringe and the mainstream religious organisations appear to be in favour of the vaccine as evidenced by this position paper by the Catholic Medical Association, showing that even while opinions on sexual morality may differ the benefits of using the vaccine can still be promoted.

That being said, the fact remains that the cancer being protected against is relatively rare and the risk to any one individual quite small. This issue not comparible to withholding vaccines for childhood diseases that would otherwise run rampant. Ultimately I still believe that the decision to administer the vaccine be up to individuals but they should also have all of the relevant information on which to base that decision. Those with paranoid conspiracy theories over “Big Pharma” need not apply.

*Proving causation is a tricky issue and I don’t really want to get into that discussion but I will admit that differences of opinion may exist.