Friday, October 7, 2011

Calculating the risk and benefit of the Pandemrix vaccine program for swine flu

Let's do a back-of-the-envelope risk-benefit calculation on swine flu vaccine:

In 2009-10, 44 Finns of all ages died of swine flu.  [With 5.3 million Finns, this is one death per 120,000 people of all ages.]

About half the population of Finland received Pandemrix.  Had the vaccine been given before the pandemic struck (a near impossibility) and had it been 100% effective (also an impossibility) it would at the very best have saved the lives of 44 people.

Seventy-nine children developed narcolepsy following Pandemrix vaccinations. [This is about one case per 17,000 children.] If the whole population received Pandemrix, probably at least 79 more children would have developed severe cases of narcolepsy (RR 12.7), and likely there would be additional adult cases as well, which were not deemed statistically significant, thus far.  There would also have been a few extra cases of Guillain Barre Syndrome (RR (1.77), and probably additional cases of other autoimmune disorders, which have not been identified because the relative risk has not been sufficiently higher than expected to be noticed.

If the vaccine had been developed and administered before there were any swine flu cases in Finland, and if it had been 100% effective and prevented every death, you would still be trading seven children developing severe narcolepsy for every person whose life was saved by vaccination.

Since Pandemrix was far from 100% effective (its effectiveness depends on the age and health status of the person being inoculated, and whether they were already immune), the health of ten, twenty, thirty or more children was probably exchanged for each life, of any age, that might have been saved by Pandemrix in Finland.  

And some people who developed additional illnesses, such as Guillain Barre Syndrome, also had their health traded for the few lives the vaccine may have saved.  Now add in the costs of purchasing and administering the vaccine, and the lifetime costs of treating and compensating those who became ill.  Do you think this is a valid trade-off?  How should public health systems handle pandemics in future?

The CDC and WHO are carefully watching out for new viruses that might cause future pandemics, so we will be prepared ahead of time, right?  But according to Dr. Steve Salzberg in Forbes, nobody is watching:
...  The 2009 pandemic originated in pig farms in Mexico. We don’t know precisely where it made the first leap into humans, but it appears that two different strains joined together in a pig somewhere to create the new H1N1. The flu has a nasty habit of jumping the species barrier, hopping to humans from both pigs and chickens.
So now that we know all this, next time will be different, right? The world’s influenza scientists are monitoring pigs and chickens closely now, keeping a close eye on any new flu strains. Right? RIGHT???
Er, no. Not exactly. For one thing, surveillance in pigs appears to be nonexistent. I checked to see how many flu sequences from pigs in Mexican have been desposited in the public archive at GenBank since 2009 (using this terrific database). The result? One, in 2009. Nothing from 2010 or 2011. Hello, is anyone awake at the CDC and the WHO?...
Why did Finland and Sweden have many narcolepsy cases, but we are not hearing about them elsewhere?  The most likely reason is that Sweden and Finland vaccinated a much higher percentage of their population than other countries, causing a much greater percentage of adverse reactions.  I have written previously about the difficulty learning how many Americans were vaccinated.  In Israel, 11.6 percent of the population took the shots against swine flu. In Spain, 10 percent were vaccinated, while in Greece, a mere 3 percent got the shots. In Sweden, by comparison, 60 percent of the population were vaccinated, and in Finland, 50 percent.

Meryl Nass, MD

From Finland's National Institute for Health and Welfare:
1 Sep 2011
An association between Pandemrix and narcolepsy among children and adolescents in Finland is confirmed.
In its final report, the National Narcolepsy Task Force confirms the tentative conclusion published in its Interim Report last January that the Pandemrix vaccine used in the winter of 2009–2010 contributed to the increased incidence of narcolepsy observed among 4–19-year-olds in Finland. According to the report, the increased risk associated with vaccination amounted to six cases of narcolepsy per 100 000 persons vaccinated in the 4–19 age group during the eight months following vaccination. This was 12.7 times the risk of a person in the same age group who had not been vaccinated. No increased incidence of narcolepsy was observed among children under the age of four or among adults over the age of 19.
In all the cases examined, narcolepsy associated with Pandemrix vaccination has been identified in persons who carry a genetic risk factor for narcolepsy. Because of this very strong association with the genetic risk factor which regulates immune responses, narcolepsy is considered an immune-mediated disease.
In approximately one quarter of those who developed narcolepsy following Pandemrix vaccination, the THL Immunology laboratory found antibodies binding to the AS03 adjuvant component of the vaccine. Adjuvants containing squalene have not previously been reported to induce the production of antibodies. (Depends what literature you read--Nass)  The significance of this preliminary observation will be the subject of further research.
Tests on viral antibodies indicated that less than 10 per cent of the children and adolescents who developed narcolepsy had been infected with swine flu. Swine flu infection thus does not appear to play a significant role or be in joint effect with the Pandemrix vaccine in the onset of narcolepsy...
By 25 August 2011, the National Vaccine Adverse Event Register maintained by THL had received notifications of 98 cases of narcolepsy subsequent to vaccination with Pandemrix; 79 of the subjects were between 4–19 years old at the time of vaccination. Narcolepsy was associated with cataplexy in 78 of the cases. Most of the persons affected developed symptoms within a couple of months after receiving the vaccination...
The Pandemrix vaccine was used in the winter of 2009–2010 to prevent the swine flu epidemic. About half of the Finnish population chose to be vaccinated.  There were 44 deaths from swine flu confirmed by laboratory tests. A significant number of severe cases were prevented during the 2009–2010 season, even if vaccines were given at about the same time as the epidemic reached Finland.  (Perhaps, but vaccine was given late, and no data are given--Nass)
During the influenza season 2010–2011, 13 succumbed. Most of these were unvaccinated. Combining the data on morbidity and mortality with data on vaccinations in the 2009–2010 pandemic season indicate that a swine flu vaccination taken in the pandemic season had provided 75–88 per cent protection against the swine flu virus in winter 2010–2011. Based on these vaccine effectiveness figures, it has been estimated that during the first wave in 2009-2010, the swine flu vaccine prevented approximately 40 000 cases of swine flu, and during the second wave in 2010-2011, another 40 000 cases of swine flu... (But are these numbers ignoring the fact that most people had already  developed immunity during the previous year of the swine flu pandemic? --estimated at over 60% of the US population by NIH researchers.  The stronger, natural immunity of people who were exposed but later vaccinated, is likely being counted as vaccine-induced protection--Nass)

1 comment:

Anonymous said...

Of those that did die of the flu, just how many of those could have been saved with fever control and replacement of electrolytes. How many died of secondary or opportunistic infections such as pneumonia ?

Often times people can be saved with simple existing measures without vaccines.