The first major documented polio outbreak in the United States occurs in Vermont; 18 deaths and 132 cases of permanent paralysis are reported.

Swedish physician Ivar Wickman suggests that polio is a contagious disease that can spread from person to person, and also recognizes that polio could be present in people who show no symptoms.

Two physicians in Vienna, Karl Landsteiner and Erwin Popper, announce that polio is caused by a virus.

A major polio outbreak in New York City kills more than 2,000 people. Across the United States, polio takes the lives of about 6,000 people, and paralyzes thousands more.

Philip Drinker and Harvard University’s Louis Agassiz Shaw Jr. invent an artificial respirator for patients suffering from paralytic polio — the iron lung.

A vaccine developed by Dr. Jonas Salk is declared “safe and effective.”

The U.S. government licenses the oral polio vaccine developed by Dr. Albert Sabin.

Rotary clubs take on a project to buy and help deliver polio vaccine to more than six million children in the Philippines.

Rotary International launches PolioPlus, the first and largest internationally coordinated private-sector support of a public health initiative, with an initial fundraising target of US$120 million.

The International Commission for the Certification of Poliomyelitis Eradication announces that polio has been eliminated from the Americas.

Health workers and volunteers immunize 165 million children in China and India in a single week. Rotary launches the PolioPlus Partners program, enabling Rotary members in polio-free countries to provide support to fellow members in polio-affected countries for polio eradication activities.

A record 550 million children – almost one-tenth of the world’s population – receive the oral polio vaccine. The Western Pacific region, spanning from Australia to China, is declared polio-free.

The Rotary Foundation raises $119 million in a 12-month campaign. Rotary’s total contribution to polio eradication exceeds $500 million. Six countries remain polio-endemic – Afghanistan, Egypt, India, Niger, Nigeria, Pakistan.

In Africa, synchronized National Immunization Days in 23 countries target 80 million children, the largest coordinated polio immunization effort on the continent.

The number of polio-endemic countries drops to four – Afghanistan, India, Nigeria, Pakistan.

Rotary’s overall contribution to the eradication effort nears $800 million. In January the Bill & Melinda Gates Foundation pledges $355 million and issues Rotary a challenge grant of $200 million. This announcement will result in a combined $555 million in support of the Global Polio Eradication Initiative.

Rotary welcomes celebrities and other major public figures into a new public awareness campaign and ambassador program called “This Close” to ending polio. Program ambassadors include Nobel Peace Prize Laureate Desmond Tutu, violinist Itzhak Perlman, cofounder of the Bill & Melinda Gates Foundation Bill Gates, Grammy Award-winning singers Angelique Kidjo and Ziggy Marley, and environmentalist Dr. Jane Goodall. Rotary’s funding for polio eradication exceeds $1 billion.

India surpasses an entire year without a recorded case of polio, and is taken off the polio-endemic list. Only three countries remain polio endemic. Rotary surpasses its $200 Million Challenge fundraising goal more than five months earlier than planned.

India goes three full years without a new case caused by the wild poliovirus, and the World Health Organization certifies the South-East Asia region polio-free. Polio cases are down over 99% since 1988.