Pandemic smallpox was responsible for 300–500 million deaths. As recently as the early 1950s, an estimated 50 million cases of smallpox occurred in the world each year. After successful vaccination campaigns throughout the 19th and 20th centuries, the WHO certified the eradication of smallpox in December 1979. To this day, smallpox is the only human infectious disease to have been completely eradicated, and one of two infectious viruses ever to be eradicated. Historically, measles was prevalent throughout the world, as it is highly contagious. According to the U.S. National Immunization Program, 90% of people were infected with measles by age 15.
Countdown to Extinction heights of popularity and critical acclaim" with this particular record. Two years after its original release, "Countdown to Extinction" was certified triple platinum and became the band's most commercially successful album, confirming that they had retained their audience in the wake of grunge. The record was nominated for Best Metal Performance at the 1993 Grammy Awards, while the album's title track won the Humane Society's Genesis Award for raising awareness for animal rights issues. The record enjoyed similar chart success outside of the United States. It managed to peak within the top 5 on the charts in the United Kingdom