Why did Florey shift early penicillin treatment toward children?

Florey shifted early penicillin treatment toward children because they required smaller doses. The Oxford team had too little penicillin to sustain treatment of large adult patients.

Albert Alexander's case made the problem clear. He improved rapidly after receiving penicillin, but the researchers could not manufacture enough to complete the course. They tried recovering penicillin from his urine, yet he relapsed when the supply ran out and later died.

Children generally weighed less than adults, so treating them required substantially smaller total quantities of the scarce drug. This allowed the researchers to test penicillin in additional patients while production methods were still primitive. Several later Oxford cases involved children or teenagers, including a four-year-old boy and patients aged 14 and 15.

The change was not chiefly about easier diagnosis, faster fevers or fewer side effects. It was a practical response to limited supply: smaller patients made the available penicillin stretch further. Industrial fermentation and deep-submergence production later solved the supply problem on a much larger scale.