Open Mike: H1N1’s Warning

I called my wife and said, This could be it.

A new flu virus had surfaced in Mexico. The first reports were ominous. People were dying. Its antigens—proteins on the viral surface that spark an immune response in people—weren’t familiar, meaning this was a new strain of the influenza virus. So perhaps no one would have immunity to it. It was April 28. Like most everyone else, I was terribly worried.

Stock up on food and water, I told her.

What concerned me the most was that this new H1N1 virus appeared to have a very high case-fatality rate. However, it later became clear that in the early days Mexico was just counting severe cases, not all cases. Thus, the proportion of reported cases who died seemed very high. The denominator (the number of everyone infected) is important too, as Epi 101 students can tell you. Data from the outbreak in New York City revealed H1N1 didn’t cause high numbers of secondary cases, nor were there any deaths initially.

Though any loss of life is tragic, we were fortunate this spring. However, this is no cause for complacency. Our immune system can protect us when it has previous experience with the proteins on the surface of a virus. But influenza viruses are notorious for changing their proteins. They are sloppy gene copiers when they replicate, so they mutate prodigiously. This results in antigenic drift (small changes in surface proteins that occur over time). Antigenic shift, usually from swapping genes between different viruses to create a new combination, causes a major change in the virus. These changes can sometimes make a mild virus more lethal and more transmissible. Will this happen this fall? We don’t think so, but we don’t know for sure. We do know that this is a virus with surface proteins that humans haven’t seen before, so more individuals will be susceptible to infection from it.

As John M. Barry chronicles in his terrific book, The Great Influenza, the 1918 flu epidemic began with a spring outbreak that returned in the fall with horrific lethality. That virus circled the world, claiming tens of millions of lives.

As our School first opened its doors to students in October 1918, our first dean, William Henry Welch, was helping lead the nation’s response to the flu—until he too fell ill. He fortunately survived after weeks of recuperation.

We have to view the latest H1N1 pandemic as a warning. Our greatest fear of a pandemic with high case fatality and high transmissibility did not happen but we have to be ready in case this virus does become more transmissible and more deadly. And we have to be ready against other pathogenic threats in the future. This means we must have strong surveillance methods in place that serve as disease early warning systems. We must have shoe-leather epidemiologists who are trained to quickly ascertain viral attack rates and case-fatality rates. We must have educated public health leaders who can marshal good data and interpret it for policymakers and the public. We must have a robust preparedness infrastructure that can respond quickly to epidemics with timely and accurate guidance on infection control, social distancing and other preventive measures.

In the long term, we must also hasten our ability to create vaccines using methods that are not dependent on the decades-old, cumbersome process of replicating the virus in chicken eggs. This kind of a quantum leap is achieved only through strong basic science programs, which deliver an ever-improving armamentarium of new tools and strategies to be wielded against pathogenic foes like viruses. Andrew Pekosz, a virologist here at the Bloomberg School, and his quest for a universal flu vaccine provide an excellent example. Influenza is too crafty, too quick to mutate for us to accurately predict every spring what deadly strain will challenge humanity the following autumn. We need a vaccine that will be effective against all strains of influenza. This requires a different approach than we have taken with seasonal flu vaccine. Only painstaking basic science can give us the kind of intimate knowledge of the virus that will show us its critical weakness.

We know that, when the world faces a new and unpredictable threat such as the emergence of H1N1, a robust public health infrastructure is essential for an effective response. In the early 21st century, the cost of inadequate support for public health is all too evident in many places of the world (including parts of the U.S.). Public health is not a light switch to be turned on only after a grave threat emerges.

The greatest lesson of H1N1 is a reminder of the centrality of public health to maintain the health of the population and the necessity to invest continually in our ability to meet societal threats head-on.