Race for the vaccine
Vaccines for illnesses such as smallpox, polio, yellow fever, tetanus and measles are credited with saving millions of lives a year worldwide. Here's a look at the history of vaccine development, including the work of pioneers such as Edward Jenner and Jo
SMALLPOX
WHAT IT IS: Scientists theorize that smallpox most likely evolved from an African rodent tens of thousands of years ago. The disease is estimated to have killed up to 300 million people in the 20th century alone. Early symptoms include high fever and fatigue. The virus then produces a characteristic rash. The resulting spots become filled with clear fluid and, later, pus, then form a crust that eventually dries up and falls off.
VACCINE: The smallpox vaccine, introduced by English physician Edward Jenner in 1796, was the first successful vaccine to be developed. He observed that milkmaids who previously had caught cowpox were not infected by smallpox. The smallpox vaccine was made from a virus similar to smallpox but less harmful.
CURRENT STATUS: A vaccination program led by the World Health Organization in 1967 helped eradicate the disease. The last known natural case of smallpox was in
Somalia in 1977.
POLIO
WHAT IT IS: A disabling and life-threatening disease caused by the poliovirus. While about 1 out of 4 people with poliovirus will have flu-like symptoms, the virus spreads from person to person and can infect a person's spinal cord, causing paralysis.
VACCINE: The first successful demonstration of a polio vaccine was by Polish scientist
Hilary Koprowski in 1950, with a live attenuated virus that people drank.
American virologist
Jonas Salk developed the more commonly used polio vaccine in 1955. CURRENT STATUS: Since 1979, no cases of polio have originated in the United States.
MUMPS
WHAT IT IS: A mild disease that typically peaks in late winter or early spring, its symptoms include low-grade fever, respiratory problems and most notably swelling of the salivary glands below the ear.
VACCINE: The virus was isolated from the throat washings of a child named Jeryl Lynn in
1963 and weakened in a lab by her father, Maurice Hilleman, a scientist. Human trials were carried out over the next two years, and the vaccine was licensed by Merck in December 1967.
CURRENT STATUS: In the United States, cases of mumps have dropped by 99 percent since the introduction of a vaccine in 1967. Unlike measles and rubella, however, mumps has not yet been eliminated in the United States, and outbreaks still occasionally occur.
HUMAN PAPILLOMAVIRUS (HPV)
WHAT IT IS: A sexually transmitted virus that infects cells of the skin and mucus membranes. Most people who contract HPV have no symptoms and quickly clear the virus from their bodies. In other people, certain types of low-risk HPVs cause genital warts and other types of the virus are the main cause of cervical cancer.
VACCINE: The U.S. Food and Drug Administration approved a Merck vaccine for four types of HPV in 2006. The FDA approved another vaccine from GlaxoSmithKline, which protects against two high-risk types of HPV, in 2009. Another HPV vaccine was approved in 2014.
CURRENT STATUS: The HPV vaccines have proved effective in preventing precancerous cervical changes and precancerous anal changes in women and men caused by high-risk cancer-causing HPV strains. Scientists are hopeful the vaccines will lead to eventual eradication of HPV.
CHICKENPOX
WHAT IT IS: Chickenpox is a highly infectious airborne disease that typically spreads through the coughs and sneezes of an infected person. The disease results in a characteristic skin rash that forms small, itchy blisters that eventually scab over. Symptoms usually last five to seven days, and the disease is typically more severe in adults than children.
VACCINE: A live, attenuated chickenpox vaccine was developed in Japan in 1979 and licensed for use in the United States in 1995. The vaccine is typically part of a child’s immunization schedule, and one dose of the vaccine prevents 95 percent of moderate disease and
100 percent of severe disease.
Two doses are now recommended. CURRENT STATUS: Prior to the vaccine, it was estimated that roughly 4 million U.S. children were infected each year. Studies of the two-dose vaccination have found that the incidence rate has dropped 90 percent from the pre-vaccine era.
MEASLES
WHAT IT IS: Measles is caused by a virus that’s spread primarily through coughing and sneezing. It causes a rash that covers most of the body and is extremely contagious: on average, 90 percent of those exposed to someone with measles will get the disease unless they’ve been vaccinated. In the decade before the vaccine became available in 1963, nearly all children got measles by the time they were 15, infecting an estimated 3-4 million people and killing 400-500 people every year.
VACCINE: American scientists John Enders and Thomas Peebles developed a measles vaccine from several students who caught the disease during an outbreak in Boston in 1954. In 1963, Enders transformed the strain of the measles virus from one of these students into a vaccine and licensed it. The measles vaccine is usually combined with mumps and rubella
(MMR) vaccines as part of the childhood immunization schedule.
CURRENT STATUS: Measles was declared eliminated from the United States in 2000, in part thanks to a recommended second dose of the MMR vaccine for children after a 1989 measles outbreak.
RUBELLA (GERMAN MEASLES)
WHAT IT IS: A virus spread by airborne respiratory droplets, rubella has symptoms that include low-grade fever, respiratory problems and a rash of pink and light red spots. The chief danger of the disease is Congenital Rubella Syndrome, which occurs if a pregnant woman contracts the virus and passes it to her fetus, sometimes resulting in birth defects.
VACCINE: Maurice Hilleman licensed the first live, attenuated rubella vaccine in 1969. Hilleman’s vaccine was used in the combination measles-mumps-rubella (MMR) vaccine, licensed in 1971. In 1979, an improved live rubella vaccine was developed that offered superior protection against the disease.
CURRENT STATUS: During the last major rubella epidemic in the U.S. in 1964-65, an estimated 12.5 million people got rubella and 11,000 pregnant women lost their babies. Rubella has been eliminated from the U.S. since 2004.
TETANUS
WHAT IT IS: A nervous system disease caused by bacterial infection. Early symptoms of tetanus include lockjaw, stiffness and problems swallowing.
Later symptoms include severe muscle spasms, seizure-like activity and severe nervous system disorders. Generally, between 10 and 20 percent of tetanus cases result in death.
VACCINE: A group of German scientists in 1890 discovered the first tetanus vaccine. A more effective version of the vaccine was created in 1938 by American scientists and used to prevent tetanus in the military during World War II. DTP, a combination vaccine for diphtheria, tetanus and pertussis, was first used in 1948 and continued until 1991 when it was replaced with a different form of the pertussis vaccine due to safety concerns.
CURRENT STATUS: Because tetanus spores are present in the environment worldwide, it cannot be eradicated. It is estimated that tetanus causes 213,000-293,000 deaths worldwide each year.