Vaccine breakthrough of 1962 saved about 10 mln lives: study

Vaccines saved more than 10 million lives globally, by preventing an estimated 4.5 billion cases of diseases such as polio, measles, rabies and hepatitis A, a new study has found.
Among these nearly 200 million cases and about 450,000 deaths were prevented in the US over the past five decades, researches said.
Scientists developed the normal human cell strain in 1962 and it has been used ever since to safely grow the viruses needed to produce vaccines against more than 10 diseases.
The recent emergence of some diseases that were previously considered dormant in the US, such as measles, demonstrates that the anti-vaccination movement is having a direct, negative effect on public health and vaccination rates for measles, mumps and rubella (MMR) in the US are now as low as 50 to 86 per cent, said Leonard Hayflick of the University of California in the US.

Researchers wanted to study how many lives had been saved by the development of cell strain WI-38.
Previously-published data on cases and deaths for each disease in the US was studied to determine the number of cases of disease and deaths prevented by vaccines developed using WI-38 from 1962-2015.

Researchers assumed that the prevalence rates would have held constant through the years without vaccines.
Since vaccines for individual disease were introduced over time, to determine how many cases were prevented and lives saved for each disease, they multiplied the number of years the vaccine has been out by the prevalence of cases and deaths caused by that disease in 1960.

"Vaccination is a particularly important issue to think about now, given the rise of an anti-vaccine movement that has the potential to reverse the health gains achieved through one of the most powerful interventions in medical history," Hayflick said.
When almost everyone in a community is immunised against a disease, if an immunised person becomes infected, the disease has little opportunity to spread because there are so few unprotected hosts. This is known as 'herd immunity.'
However, if enough people forego vaccination, outbreaks can occur as the disease spreads among unprotected individuals, researchers said.
The study was published in the journal AIMS Public Health.