H1N1 Update

I know we have been focusing on the vaccine issue extensively, but this is crunch time and the anti-vaccine forces are relentless. We are now facing a regular seasonal flu spiked with the H1N1 pandemic. Our best weapon against morbidity and mortality caused by the flu is information, and yet the public is being barraged with misinformation designed to encourage poor choices and thereby result in maximal morbidity and mortality.

I confess I was never impressed with FDR’s famous quip, “All we have to fear is fear itself,” – I think there is plenty else to fear. But his sentiment is very appropriate to the current situation – fear mongering around the seasonal flu and H1N1 vaccines is what we have most to fear.

And of course, as is almost always the case, accurate information is complex and requires a nuanced understanding. This creates uncertainty, which is easy to exploit to manufacture unreasonable fear.

The anti-vaccine fear mongers are playing every card in the deck. They are arguing (falsely) that H1N1 is not severe enough to warrant getting the vaccine, that the vaccine does not work anyway, and that there are unacceptable or unknown risks to the vaccine. In the most extreme cases, bizarre conspiracy theories are brought to bear, but I will not discuss these here as anyone compelled by such fantasies is likely beyond the reach of any information I could provide.

Mark Crislip has already provided an excellent overview of the evidence for seasonal flu vaccine efficacy in adults. To summarize – the evidence is complex and mixed, but there is compelling evidence that the flu vaccine works as designed, in that it produces protective antibodies against influenza. There is also evidence that it decreases morbidity and complications from the flu, although it is less clear if it decreases the number of flu cases. Further, the efficacy of the vaccine depends highly on how well the strains vaccinated against match the circulating strains.

Efficacy also depends highly on compliance – the percentage of the population (especially those likely to spread the flu to vulnerable populations) who get the vaccine.

The bottom line is that the vaccine works enough to make it worthwhile, and it is extremely safe. At a time when health care costs are crushing our economy, it is also worth pointing out that it is cost effective.

And yet confidence in the H1N1 vaccine is decreasing under the onslaught of scare mongering and misinformation. A recent survey of UK nurses found that 47 percent do not plan on getting the H1N1 vaccine, while only 23 percent said they would. This is concerning because health care workers are perceived as having more authority with the public, and because protecting the sick and elderly likely depends most on their health care providers getting vaccinated.

It is also important to note that the H1N1 vaccine has a big advantage over the seasonal flu vaccine – the match between the vaccine and the circulating virus is high. This is perhaps the biggest predictor of efficacy for the flu vaccine.

How Bad Is It?

The evidence so far indicates that, as predicted, H1N1 is now making its second circuit through Western countries, including the UK, Canada, and US. The CDC reports that flu cases are increasing rapidly, and are exceeding the normal number of cases that would be seen at this time of year from the seasonal flu. By all reports, we are in for a heavy flu season. It does not look like the 1918-1919 pandemic, but a bad flu season is still a concern. The average flu season kills 30,000 Americans and 500,000 worldwide.

Statistics from August 30 to October 3 in the US indicate: Influenza and Pneumonia Syndrome – 12,384 hospitalizations and 1,544 deaths, of those influenza was confirmed in laboratory tests in 3,874 and 240 respectively.

Compared to the seasonal flu H1N1 is about as deadly overall, but kills a higher proportion of those who are otherwise young and healthy, and also is more deadly for pregnant women. About 1% of people infected with H1N1 get a severe form of the flu likely requiring hospitalization and at high risk of death.

Is the vaccine safe?

There is a range of concerns that have been raised about the vaccine. These range from those that are reasonable and should be raised about any new intervention at one end, to outrageous conspiracy mongering at the other. Of course, those who raise appropriate concerns hate to be painted with the same brush as the conspiracy theorists, and so I will make that distinction at the outset. And, as stated above, the conspiracy theories are beyond the scope of this entry.

I would file under appropriate concerns the fact that the previous H1N1 pandemic vaccine from 1976 resulted in an increased risk of Guillain Barre Syndrome (GBS) – about 1 per 100,000 people vaccinated. The seasonal flu vaccine in the last 32 years has resulted in excess cases of GBS of about 1 in 1 million. While we expect that the H1N1 vaccine will likely have the same risk of GBS as the seasonal flu vaccine, the US and UK have instituted monitoring systems (essentially encouraging doctors to report cases of GBS following vaccination) as an early warning if the H1N1 vaccine has a higher risk of GBS.

I discuss the issue of GBS in more detail here, but the bottom line is that the risk of GBS ranges from low to very low, and it will be monitored. Also, early experience with the H1N1 vaccine has not resulted in any cases of GBS, so at the very least the risk is not high.

Most of the concerns brought up about the H1N1 vaccine I consider to be unreasonable fear mongering. For example, anti-vaccinationists have tried to raise fears about adjuvants in the vaccine. They consistently fail to point out that the versions of the vaccine approved by the FDA for use in the US do not contain adjuvants.

Adjuvants are substances added to vaccine to increase the immune response. This allows for the use of less viral material in the vaccine. Vaccine adjuvants are all extensively tested and are generally safe. Any reactions are extremely rares, and certainly much less likely than morbidity from the disease the vaccine is targeting.

Harriet Hall has already addressed the fear mongering surrounding squalene and other adjuvants here, and David Gorski addresses similar concerns here.

Another concern that is brought up is that one can get sick from the vaccine itself. Bill Maher infamously stated recently on his show that the vaccine “injects disease” into the arm. The injectible version of the vaccine does not contain “disease” – it is a killed virus vaccine, and it is impossible to get the flu from the vaccine. The nasal spray vaccine does contain a live virus, but it is an attenuated virus – meaning that it is weakened so as not to cause illness but only to provoke an immune response. There is a small risk that attenuated viruses will spontaneously mutate and revert back to a more virulent form, but the risk is very small.

And, of course, the now classic vaccine scare mongering regarding thimerosal, a mercury-based preservative, is being trotted out. These claims are wrong on multiple levels. We have already dealt extensively with the false claim that thimerosal is unsafe. A thorough review and reference list can be found here. Thimerosal is safe in the doses used in vaccines.

Further, the single-shot version of the seasonal and H1N1 flu vaccines, and the nasal vaccine, all do not contain any thimerosal. Thimerosal is only used in the multi-shot version of the vaccine, to prevent contamination.


While there is uncertainty and reasonable concerns regarding the flu vaccine, and more research is welcome, current evidence is sufficient to recommend that the vaccine is safe and effective. The bottom line with any medical intervention is risk vs benefit. The benefit of the H1N1 vaccine far outweighs the minimal risk.

Further, the more people who get the vaccine the more effective it will be. At this rate, we are unlikely to achieve herd immunity, but everyone who gets vaccinated will not only provide themselves with a level of protection, but will also protect those around them.

It is still too early to tell how severe the H1N1 pandemic will be, but at least it will result in a bad flu season. It is also clear at this point that the pandemic will be significantly worsened by fear-mongering against the most effective defense we have against the flu – the vaccine.

There is a body count attached to this unreasonable fear, justifying FDR’s famous words.

Posted in: Public Health, Vaccines

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