There is some hope that a massive pandemic like 1918 might be avoided in the future with well-conceived counter-measures, prevention, and some good fortune.

In the most recent pandemic, three levels of prevention were used: first, an international surveillance system at the global level; second, a system of pre-emptive vaccination; and finally, an emphasis on personal prevention. But each of these tools has benefits and drawbacks, which are exacerbated by human error or misunderstandings. In 2009, humans around the planet made mistakes in judgment that are eerily familiar to problems in past anti-influenza campaigns and helped to spread the virus.

Global Influenza Monitoring

The worldwide system for determining and monitoring pandemics is a relatively recent invention. In 1918 there was no planet-wide health organization like the WHO, and, while there were radios and telegraphs to spread information, there was no CNN to report its findings to a waiting world or obviously no internet. The only international system for coordinating disease, the Paris-based International Public Health Office, was all but shut down as a result of World War I.

To make matters worse, the war slowed down the spread of crucial information about the disease in other ways. Anxious to avoid giving away potential military advantage, states involved in World War I refused to release flu data. This is why the 1918 pandemic was referred to as the Spanish Flu. Spain didn't participate in World War I, so it published its disease statistics internationally while other nations did not.

In the 1950s, the WHO adopted the pandemic influenza warning system that had been developed informally in the 1940s amongst doctors who had lived through the 1918 pandemic. The WHO early warning system effectively picked up on the 1957 and 1968 pandemics before they spread, which helped to prevent a devastating flu pandemic.

Today, the WHO and national epidemiological intelligence centers such as the Centers for Disease Control and Prevention (CDC) in Atlanta, as well as a network including more than 100 laboratories worldwide, coordinate the epidemiological data that makes declaring a pandemic possible.

They also centrally determine what strands of vaccine should be prepared, manufactured, and shipped around the world in a complicated web of international, national, not-for-profit, and commercial organizations. Although the WHO determines the strains that should be included in the vaccine, production and approval is left to the appropriate national or regional drug-approval body.

This early warning system has become vital to influenza control efforts even if it has sometimes led to false-positives, such as in 1976 and the recent attention to H5N1 Avian flu. The overlap between national and international bodies, however, has complicated a number of key steps in anti-influenza campaigns, most notably vaccine production.

Vaccines

Vaccines have become another standard first line of defense against seasonal flu.

In 1933, a ferret in a British medical lab sneezed on a researcher infecting him with flu. While the scientist was likely not pleased to be infected, it was a great moment in medicine because it established that viruses were responsible for human influenza.

Until then, the world had assumed that flu was caused by a bacterium discovered by German scientist Richard Friedrich Johannes Pfeiffer at the end of the 1890 pandemic. Flu vaccines targeted this bacterium in the early twentieth century. However, faith in Pfeiffer's bacillus did not survive the 1918 pandemic. His vaccines simply did not stop the disease.

After 1918, many scientists came to believe that the flu was caused by a so-called "filter passing virus." Their belief was backed up by the fact that when examined, the secretions of influenza patients did not contain a common organism that seemed to be causing the disease. Thus, they reasoned, the disease must be caused by something smaller that they could not catch. An influenza virus was identified in pigs in 1931, but not in humans until that fateful, snotty-nosed-ferret day in 1933.

With the virus found, a vaccine was in reach. Soldiers in World War II were among the first to receive the new vaccine, as military planners feared that the Second World War might bring with it an influenza pandemic like the previous world war. In fact, the egg technology used today to produce influenza vaccines dates to the 1950s.

In the 1957 and 1968 pandemics, public vaccine programs were in their infancy. Just 15-20 million doses of vaccine were made annually in the United States. Only 8-12 million American civilians were annually vaccinated, which meant that there was no capacity to easily and quickly vaccinate large numbers of people, either in the United States or around the world.

With the early warning provided by the WHO in 1957, however, the American government decided to gear up to vaccinate more widely. Negotiations with vaccine producers immediately proved difficult. They were hesitant to produce an expensive product when there was no proof the pandemic would reach the U.S. When they at last agreed to make the vaccines—because evidence could no longer be ignored that the pandemic had indeed grown—it was essentially too late.

Although the U.S. managed to vaccinate a larger percentage of the population than ever before, it was only after a period of panic that there would not be enough available. With vaccine production starting late in the game, the American vaccination program also came at the cost of many unused vials of vaccine that came off the production lines after the pandemic had essentially passed. Not much was learned from these experiences and a similar pattern of events occurred in 1968.

Then came the 1976 swine flu scare. With the makings of another swine flu pandemic, the American government authorized the National Influenza Inoculation Program. The program seemed cursed from the beginning. The country lacked the ability to produce the vaccine in the requisite quantities, and what it did produce appeared to cause serious neurological problems in a small number of patients. Panic ensued.

Today, it is unclear whether there was in fact any link between the symptoms and vaccine, but the incident prompted tremendous concern at the time. Only 30% of the population was vaccinated despite hopes that upwards of 90% would be. Even after more than a quarter century of safe vaccine, mass vaccination rates still hover at about where they were in 1976, at around 30% of the population.

This year, a similar series of events unfolded. The strain of influenza that turned pandemic was not mixed into the seasonal flu vaccine because it was not seen as a threat at the time vaccines were being produced. Few people had been sickened by H1N1 when the decision was made over what would go into the seasonal flu vaccine cocktail, and experts still focused their attention on the Avian strains. Once it became clear that the 2009 H1N1 virus was likely to spread, there was a scramble for vaccine. Alarm broke out in many regions as the vaccine remained scarce, and calls of queue jumping were common when hockey players, Wall Street moguls, and politicians seemed to get the limited vaccine before the rest of us.

By early 2010, there was excess vaccine in many places where there had been a shortage earlier. France and Canada are looking to sell theirs to a world that may no longer need it, repeating the mistakes of the past. The current version will offer limited protection next year, given that many have already had the disease and other flu viruses will evolve for the next season, making the single strain vaccine developed on the fly this year too little, too late.

Local Measures

Despite the advances (and institutional difficulties) of monitoring systems and vaccines, one of the best preventive steps against the spread of flu was and still is to change human 's weave was actually too loose to trap the virus. Modern paper and cloth masks are much more effective. A study reported on in the Annals of Internal Medicine found that family members of influenza patients drastically cut their risk of infection if they wore masks and washed their hands regularly.

Finally, public education campaigns have focused on having people change their day-to-day habits to limit the spread of the disease. Health campaigns to have people stop shaking hands or hugging when greeting met with limited success. Yet, many more people responded to suggestions to sneeze or cough into a sleeve rather than the hand, to prevent transferring viruses to other people.

Lessons Learned and Future Pandemics?

The twentieth century was largely one of triumph for medical science. Antibiotics were discovered, and innumerable life-saving therapies developed. In the west, we have the privilege to think that we are, for the most part, immune from contagious diseases.

The influenza outbreak challenges this hard-won privilege. The flu virus remains, despite the best efforts of medical and public health professionals, a difficult foe. At the beginning of the twenty-first century, we are almost as susceptible to it as we were 90 years ago, thanks to the convergence of biology, politics, technology, and individual action.

In late March, the CDC held its first press conference on swine flu in months. A recent outbreak in Georgia had left 40 people hospitalized and the CDC believed it was a result of vaccination problems. Unlike in the past, however, in this instance, vaccine was readily available. Many of those hospitalized, along with the majority of American adults, had simply chosen not to take the vaccine offered, despite the fact the CDC estimated that there were 140 million excess doses available by early 2010.

It is too early to say why many adults have not received the vaccine. Was it poor publicity of the availability of the vaccine following the early shortages? Were the vaccines not covered by insurance plans or otherwise unaffordable? Did they have underlying health problems that made taking the vaccine ill-advised? Or were they part of a growing movement of vaccine refusal?

In the European Union, some accused the WHO of declaring a pandemic to line the pockets of vaccine manufacturers. Others maintained, despite all evidence to the contrary, that the vaccine was unsafe, tapping into older anti-vaccine feelings. In the United States, a growing number of adults are regularly refusing vaccines, resulting in an estimated extra 50,000 deaths annually from pneumonia, influenza and other diseases.

As with influenza vaccines, there are few controls or mechanisms for vaccinating adults. Most successful vaccination campaigns—such as the MMR vaccine or polio in years gone by—are conducted on infants or school children. How to distribute vaccine is a complicated technological, administrative, political, medical, and social problem.

This latest influenza outbreak highlights the unpredictability of flu epidemics, and the complexity of the problem to be solved. While medicine and science traditionally look forward, the messy social and political problems inherent in defending ourselves against epidemics suggest that looking back to appreciate that epidemics are not just medical but administrative problems would help us plan better.

Because one thing is certain: there will always be another flu season.