Perspectives in Health Magazine
The Magazine of the Pan American Health Organization
Special Centennial Edition
Volume 7, Number 2, 2002

Vaccines have helped us conquer some of humanity's worst scourges in the past century. In the future they will help us control and even eliminate many more.

It took 181 years from Edward Jenner's introduction of a smallpox vaccine for public health efforts to succeed in eradicating that disease from the globe. Even today, the gap between the introduction of a vaccine in the industrialized countries and its use in the poorer nations remains dauntingly long. Yet vaccines have proven themselves to be the most cost-effective public health tools in history.

How will progress in vaccines affect public health in the next 100 years? What lingering diseases will they help us conquer? How will their global use be financed? What lessons from experience can be applied to future vaccination campaigns?

If one had a crystal ball to look at the future of vaccines, it would no doubt reveal some important and heartening milestones, possibly including the following:

• By 2005, significant progress toward if not achievement of the global eradication of polio
• By 2010, vaccines against meningitis, pneumonia, rotavirus-caused diarrhea and human papilloma virus (the cause of cervical cancer)
• By 2015, vaccines against AIDS, malaria and pulmonary tuberculosis, and the global control of measles
• By 2025, the ability to protect infants against at least 20 pathogens throughout their lives

In reality, we can only speculate meaningfully on the future by thoroughly analyzing the past and present. Yet even in that real-life context, the prospects look bright indeed for a major impact of vaccines on global human health.

Smallpox is an important and encouraging case study. Though the vaccine has been around for more than two centuries, it took a mere 11 years for a disciplined campaign that was adequately financed and brilliantly led to achieve eradication. What came as an encore?

Just as smallpox was nearing eradication in the late 1970s, the World Health Organization (WHO) launched the Expanded Programme on Immunization (EPI), which included six infant vaccines: against diphtheria, pertussis, tetanus, poliomyelitis, measles and tuberculosis. Although EPI got off to a slow start, the concept of universal childhood immunization was embraced seriously from 1984 on.

As a result, global immunization of infants rose progressively to just under 80 percent coverage by 1990. This overall statistic, however, hides the fact that coverage was quite uneven. In countries with per capita GDP of less than $1,000, coverage reached a mean of just over 50 percent. In the Americas, coverage was much better (often spectacularly) than the global average.

Unfortunately, since 1990 no real further progress has occurred, and indeed coverage has slipped in a number of countries, with coverage in the poorest countries now at just over 40 percent. EPI has saved many millions of lives and must be counted as a success. Yet globally there are still at least 2 million vaccine-preventable deaths every year in children under 5.

Polio eradication
With the Americas once again in the lead, global polio eradication efforts began in earnest in 1988. It was soon realized that routine infant immunization, although essential, could not do the job alone. It was buttressed by three additional strategies: national immunization days (NID), a global system for surveillance, and "mop-up" operations, that is, intense vaccination efforts around the last few index cases.

National Immunization Days represented a huge effort in social mobilization, receiving extraordinary help from Rotary International, the news media, the government sector and, particularly, highly involved health ministries. On a single day, all of a country's children under 5 were lined up and given the oral Sabin vaccine. This succeeded in finding many hard-to-reach children who, for one reason or another, had not been caught in the routine immunization net.

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