September 10, 2012

Swine Flu Update: H3N2v Now Spreading Among Humans

Tyler Smith

Tyler Smith

Program Officer, Food Production and Public Health

Johns Hopkins Center for a Livable Future

The H3N2v influenza virus continues to spread.  The U.S. Centers for Disease Control and Prevention (CDC) announced on Friday that the strain has infected at least 297 people so far this year (up from 12 in 2011).  At least one person, a 61-year-old woman in Ohio, has died as a result.  The agency has also confirmed that H3N2v is spreading between humans, not just from pigs to fairgoers.

This is cause for concern.  Viruses evolve quickly, and the public health community has feared for many years that an influenza virus circulating in non-human hosts will jump to humans and spread rapidly among us.  This is what happened in 2009 when an H1N1 influenza strain jumped from pigs to humans, infecting at least 1.6 million people and killing at least 19,000 worldwide.  There is no indication yet that H3N2v will do the same, but the CDC and state health departments are monitoring the situation closely.

CLF’s director, Dr. Robert S. Lawrence, recently penned an article for on how industrial food animal production (IFAP) increases the risk of pandemic influenza. To recap: When viruses infect cells and reproduce, their genes can change both through mutations and by the reassortment of genes from other viruses that infect the same cell.  As viruses infect and reproduce more often, genetic changes occur more frequently.  Some changes advantage the reproduction and spread of the viruses in which they occur, and these viruses outcompete others to become the dominant strains in circulation.

The concentration of thousands and sometimes millions of poultry or swine at IFAP sites is a good example of this.  With so many animals, influenza viruses have ample opportunity to infect and reproduce, and some viruses may acquire the ability to infect humans. IFAP workers are in near-constant contact with these animals throughout the workday and human infectivity could advantage such viruses by allowing them to infect these human hosts.  IFAP workers may then serve as “bridge populations” that can spread influenza viruses from IFAP sites to surrounding communities and beyond.

To reduce the probability of an influenza pandemic, we should reconsider the industrial model by which the majority of food animals in this country are produced.  It is often claimed by the food animal industry that this model has resulted in unprecedented efficiency—animal protein appears to be cheaper than ever before.  But the prices of meat, dairy, and eggs in the grocery store do not capture the true cost of how these commodities are generated; they do not include the massive public health and environmental costs externalized by the industry and thus foisted upon the larger society.

Influenza is one example of this.  CDC researchers estimated that another influenza pandemic, more deadly than H1N1 in 2009, could cost $71-166 billion in the U.S alone.  Another example is antimicrobial resistance (AMR), to which IFAP is an important contributor.  It has been estimated that AMR increases U.S. health care spending by as much as $26 billion each year.  Neither influenza nor AMR is solely attributable to IFAP, of course, but IFAP contributes to both and should be remembered when industry groups argue that meat is cheap.


  1. What a sensible idea,Tyler! Address meat production practices where the contamination occurs – Brilliant! And you’ll get a much tastier product, fully nutrient-dense,raised humanely and sustainably. As this concept is implemented more advantages are sure to arise.

    Even though the CDC claims the flu vaccine to be 68% effective – nil effect for Seniors – that figure is misleading according to the Alliance for Natural Health and aren’t good enough odds to convince me.
    Below is a quote from the ANH:

    “. . . There are currently three different “epidemics” hitting the US: “true” influenza (type A, type B, or seasonal H1N1 influenza), norovirus (“stomach flu”), and whooping cough. According to a meta-analysis published in the weekly peer-reviewed medical journal The Lancet, the flu vaccine is only 62% effective in preventing type A or B influenza or seasonal influenza A (H1N1). It doesn’t protect at all against norovirus and whooping cough. In other words, only 2.7% of all adults get type A or B or H1N1 influenza, and of them, the vaccine will fail 38% of the time, which means it really benefits only about 1.8% of the population.”

    It goes on to say that this year, two of three strains were ‘right’ as far as designing a vaccine – to benefit less than 2% of us.

    Let us all work towards the emerging paradigm change in a holistic approach to change and what will surely be a decrease in legitimate disease concerns.

  2. Hi Lynn,

    Thank you for your comment. It really is important to address food production practices that increase public health risks. And yes, the benefits do not stop at reducing the risk of pandemic influenza — other public health, environmental, animal welfare, and rural community concerns are important as well. I agree that sustainable food often tastes better too.

    That said, it is very important that people get a flu shot. The vaccine may not be 100% effective but it is a proven public health intervention that protects millions of Americans each year. It certainly reduces the risk of contracting an infection and transmitting the virus to others. I do not know of anyone in public health, including anyone at the Bloomberg School, who does not think it is important to get a flu shot.


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