Live-Virus Vaccine

While U.S. health officials still rely exclusively on Salk killed-virus vaccine in the fight against poliomyelitis, a dozen countries around the world are testing live-virus preparations—all developed, ironically, in the U.S. Early results are highly promising, and so far no ill effects have been reported despite the seemingly greater danger with live virus.

All live vaccines must be made with viruses that have no power to cause disease. A few occur that way in nature. Most are formerly virulent strains that have been "attenuated" by growing them in animals (or eggs) that are not their natural prey. These must then be tested to make sure that after being allowed to grow in the human digestive system they do not revert to virulent form. No such reversion to type has been detected in tests that have now covered more than a million subjects.

Leaders in perfecting live vaccines against polio have been the University of Cincinnati's Dr. Albert B. Sabin (TIME, May 23, 1955), and Dr. Hilary Koprowski. who began the work at Lederle Laboratories, then switched to Philadelphia's Wistar Institute. Dr. Sabin revisited his native Russia in 1956 to report on his early tests, so impressed Soviet medical men that they went to his Cincinnati labs for vaccine samples.

Economy Model. Moscow's Professor Mikhail Petrovich Chumakov tried this material on 30,000 children. He was delighted with its simplicity. His staff had to put only one droplet in a teaspoonful of syrup, and the kids swallowed it—thus cutting out the need for hypodermic needles, which are expensive and can be dangerous. Then there was the economy: one-hundredth of the injection dose. Perhaps most important: live virus taken by mouth multiplies in the digestive tract, quickly triggers development of antibodies and protects the whole system. The Russians argue that the killed form, injected into the bloodstream, safeguards only the nervous system (against paralysis).

Chumakov began brewing Sabin-type vaccine at the Institute for the Study of Poliomyelitis, a rambling frame building among the railroad yards on Moscow's outskirts. Last week he was readying the world's biggest test of live polio vaccine, had 300 liters on ice—enough for 10 million people. No small operators, Chumakov and colleagues dreamed of immunizing all the Soviet Union's 200 million people regardless of age (600 million doses, since vaccine for one strain of each of polio's three main virus types is given in separate swigs, a month apart). Satellite Czechoslovakia has used all three types, immunized 143,000.

Sabin-type vaccine got a different type of test in Singapore when it was hit by a polio epidemic last August. British-trained Professor James Hale decided to work with Sabin's Type II vaccine. All the polio occurring was of Type I. If any Type II disease showed up, it would be almost certainly due to faulty vaccine. But while Type II vaccine is supposed to give 100% protection only against Type II disease, it is claimed to give about 60% protection against Type I also. As hoped, Type I disease began to decline sharply as 205,000 children under eleven took their medicine (it took the riot squad to control the crowds), and there was not a single case of Type II disease.