"But when I asked my Mum why, she said when I arrived my arms were very sore and they were bandaged. I didn't know anything about vaccination trials. I've since been to a few doctors and they said they'd never seen anything like it - with so many injections."
Sister Sarto, a former social worker at Bessborough House, admitted that the vaccination testing took place at the home, but told Newstalk radio that parental consent was sought for the trials.
"The doctor would come here and say could they carry out this experiment, and the mother would bring the child into the doctor's. You couldn't do it without the mother's permission," she said.
GlaxoSmithKline, which took over the drug firm that ran the trials, Burroughs Welcome, said the activities, if true, were "very distressing" and that it would cooperate with any investigation. There were no laws on medical testing in Ireland until 1987.
Results of trials on 58 children at six homes, including Bessborough, were published in the British Medical Journal in 1962, and in June 2001 an inquiry was ordered into the experiments.
But that inquiry was halted when Prof Patrick Meenan, one of six authors of the original study and by then aged 86, said he should not have to appear on grounds of his age and ill health.
A subsequent inquiry was blocked by Irene Hillary, a former professor of microbiology, in 2004.
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• Hundreds of children's bodies in mass grave
The disclosure followed last week's scandal over the deaths of 800 children whose remains were discovered in a concrete septic tank at at the Tuam home for unwed mothers and their infants in County Galway. Research by Catherine Corless, a historian, uncovered a mortality rate among "illegitimate" infants that academics described as "staggering".
Government records show that throughout the 1930s, 1940s and 1950s, the death rate was often more than five times that of children born to married parents.
On average, more than one in four children born out of wedlock died.
"I have been saying for years that we need answers about what exactly happened at places like Bessborough," said John Barrett, who was born there in 1952.
"There could well be thousands of babies buried there."