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What were the pros and cons of the killed and live vaccines of polio?

Answers:1   |   LastAnswerAt:2011.04  

Asked at 2011.04.21 21:03:47

answer greydoc6  Answered at 2011.04.21 21:03:47
It helps to look at the question from a historical point of view.

The first Salk vaccine around 1954 was a killed virus vaccine. Immunity was not permanent, and a booster was recommended about every 5 years. Except for a lab error in a batch prepared by Cutter Labs, it was very safe. The vaccine produced immunity from the disease, but it did not prevent the virus from multiplying in the intestine, so it was less successful in stopping acute epidemics of polio.

The live oral polio vaccine developed by Albert Sabin produced a much longer immunity, making the need for boosters less important. It also produced an intestinal immunity that blocked viral replication in the gut, making it more effective in epidemic situations. The downside was that the attenuated (weakened) virus could revert to the wild (disease producing) type, causing paralytic polio (VAPP). The statistics reporting the frequency of this happening are somewhat confusing. The overall risk was one case in 2.4 million doses of vaccine distributed. But when looked at another way, the rate of Vaccine Associated Paralytic Polio after the first dose of vaccine was one in 750,000, including the recipient and contacts of the recipient.

Around 1987, Pasteur-Merieux developed an enhanced potency killed virus vaccine made from the Salk model which enhanced intestinal immunity and eliminated the need for boosters after the age of five or six. Except for rare allergic reactions, it is extremely safe. It remains the preferred vaccine in the United States and inmost other countries.
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