Thinking Beyond Science

For centuries, humanity has fought contagion, working hard to catch, treat or prevent disease, but success has been limited, short-term, and any progress met with an onslaught of new arrivals – or the same enemy in new armor. The war continues today, as only one battle has truly been won to date, against smallpox, an ancient virus once feared throughout the world and thought to date back at least 3,000 years to the Egyptian era. The virus killed 300 million people in the twentieth century alone and its end is considered to be the biggest achievement in international public health.

But most experts know another victory of this sort will be challenging, most likely impossible, as smallpox was a comparatively straightforward target. Multiple efforts beforehand had failed: first against hookworm, then yaws, then malaria, and current efforts to end two other diseases – polio and Guinea worm – are lagging decades behind.

An intensified program to eradicate smallpox began in 1967, when there were still more than 10 million cases occurring across 43 countries. By this point, the disease had already been eliminated – meaning it had stopped spreading in a particular geographical region – in North America and Europe, following an initial effort to end the disease, launched by the World Health Organization (WHO), in 1959. The program had focused on vaccinating the masses and the target had been to get at least 80 per cent vaccine coverage in every country in order to reach the herd immunity threshold, a level of coverage where the chances of unvaccinated people getting the disease is extremely low.

Epidemiologist Dr William Foege soon implemented a surveillance and containment strategy under Henderson’s leadership and significant reductions were quickly accomplished. For example, Foege’s team used limited resources to focus solely on outbreak-affected areas when working in eastern Nigeria in 1967, identifying cases and vaccinating everyone within a defined radius of an outbreak, known as ring vaccination. This curtailed the outbreak within five months, despite just 750,000 people of the 12 million people living in the region receiving the vaccine.

This event instigated a program of consolidation or destruction of remaining specimens of the virus, explains Heymann. This took place during the Cold War, and countries were offered the choice of giving their smallpox stocks to the United States, to the USSR, or destroying their stocks under a set protocol. Both the US and Russia continue to hold on to the stocks given to them, monitored and handled by the World Health Organization under a WHO agreement set in 1979. The US stock is held at the Centers for Disease Control and Prevention (CDC) in Atlanta and the Russian stock at a research laboratory in Siberia. The two facilities are inspected by the WHO every two years.

Officially, though, smallpox has been eradicated, with Ali Maow Maalin being the last face of the smallpox pandemic that plagued the world for millennia. The eradication laid the groundwork for the routine vaccination programs now implemented globally, in the WHO’s Expanded Program on Immunization, protecting children from multiple childhood diseases including measles, polio and tetanus.

Smallpox had many factors on its side: the vaccine was heat stable and did not require refrigeration for storage, an invaluable property in the remote, tropical settings in which the vaccine was used; immunization required just a single vaccine dose; and everyone who had the disease could be identified by its distinctive rash and therefore easily isolated and their contacts vaccinated. Other diseases do not have this combination of winning elements; some have just a few, and most only one or two.

Source – Outbreaks and Epidemics: Battling Infection in the Modern World by Meera Senthilingam, Brian Clegg (Series Editor)

Goodreads – https://www.goodreads.com/book/show/44784435-outbreaks-and-epidemics