Eradication of smallpox a global first Polio is

Eradication of smallpox —a global first (Polio is next—if we don’t abandon the plan!)

Global eradication of smallpox: a victory of the Cold War § 1958, Minneapolis: Russia challenged World Health Assembly to begin global eradication § 1966, LBJ: International Cooperation Year, support global eradication § 1979: eradication achieved § Cost: $300 million, 21 year campaign (19581979), plus contributions of national and local health authorities.

Why smallpox was an ideal candidate for eradication (as Jenner recognized) § Humans were the only repository § Immunity easily acquired through vaccination —and persisted longer than thought § Heat-stable vaccine suitable for any climate § Highly efficient, low cost mass vaccination device § Surveillance was effective: the disease was easily recognized § Rings of containment prevented spread

Case of New York City, 1947 § 1 index case led to 12 additional ill, 2 deaths § Disease not recognized until 2 patients in the hospital contracted the disease § 24 -hour vaccination service; 2 million vaccinated in first two weeks; § 6. 3 million vaccinated in a month; 8 deaths from the vaccine § Had the vaccination program been delayed by 1 week, >4, 000 cases, with perhaps 900 deaths

Why rings of containment accompanied by mass vaccination work: Smallpox is slow to develop (12 th day) vaccination ‘takes’ quickly (by 9 th day)

Rings of containment, encircle every outbreak: vaccinate and quarantine

Eradication certified: Dec. 9, 1979

Global eradication of smallpox: a victory of the Cold War § Smallpox vaccination “has averted more human suffering and saved more lives than any other single medical intervention. ” § “Had smallpox not been eradicated, in the past twenty years, 350 million new victims, and an estimated 40 million deaths” § Eradication required the mobilization of existing health structures in countries around the world

New candidates for eradication (World Health Organization) § Polio, victory when? § begun 1988 (Rotary International raised ¼ billion$ in two years) § incidence has shrunk 99% to fewer than 500 cases worldwide in 2003 § In 2003, wild polio-virus remains in only 6 countries: Afghanistan, Egypt, India, Nigeria and Pakistan. § 2004 spread from Nigeria to Mecca and beyond § Leprosy: Using multi-drug therapy reduced number of cases from 12 million in the 1980 s to less than 1 million in 2000

Smallpox and Bioterrorism

Use of smallpox as a weapon, 1763 -1775 § Used by British against Indians in the French. Indian war (1763): “…we gave them two blankets and a handkerchief out of the Smallpox Hospital” § Battle of Quebec, 1775: Smallpox defeated the rebel American army. § British against American rebels (1778): “Dip arrows in matter of smallpox and twang them at the American rebels…”

Smallpox: bioterrorist threat is real, but is it exaggerated? § Smallpox is highly contagious—but § Some residual immunity may remain § Vaccination stocks are substantial, sufficient for entire US population § What is the risk of an outbreak? Not a medical question. § Mortality (30%) is exaggerated—high figures are for small populations (Boston, 1721, 14%) § Risk of vaccination complications may out-weigh benefits—until an outbreak is confirmed

Dangers of smallpox as a weapon § Virus can be manufactured, stored and made into an aerosol. § Once released, contagion would spread through nonimmune population. However § Extremely difficult to obtain stocks and to manufacture. § Not as contagious as measles or flu—and substantial residual immunity remains among older adults. § Virus spread is “slow moving” (Rand Study, 2002)

Why vaccinating lots of people is not a good idea: risk are high and rings of containment effective § Vaccinating every American 400 deaths. § Particularly risky for those with immunodeficiency and infants (<2 years) § New vaccine may have lower risk § Residual immunity among older adults, vaccinated 30 or more years ago § Recently vaccinated “can transmit the vaccinia virus to patients in the hospital setting, where it is fatal in as many as 11 percent of cases”

From the New England Journal of Medicine, Jan 30, 2003, a contrarian view: Thomas Mack § Vaccinate 15, 000 essential epidemiological personnel (not 10. 5 million as proposed by the President 30 deaths) § In the unlikely event of an introduction, number of cases could be contained and deaths limited to “ 10”. § Even then, mass vaccination is not justified because the number of deaths from vaccine will be greater than from smallpox § Be prepared, but wait until the first case is identified

Should remaining stocks be destroyed?

Destruction of remaining stocks of smallpox: principal opponent: US Defense Department § § Pro destruction An unnecessary risk: little benefit from maintaining stocks Take the moral high-ground Con Stocks may be used to develop a “cure” May be useful in developing new vaccines