"I was less successful in my attempts to effect preventive vaccination against typhus by using the virus and in trying to produce large quantities of serum using large animals"

In this quote, Charles Jules Henry Nicolle is discussing his efforts to prevent the spread of typhus through vaccination and serum production. He admits that he was not as effective as he had hoped in these undertakings. He particularly points out using the infection itself for vaccination and utilizing big animals to produce serum, however it appears that these techniques did not yield the wanted results. This quote highlights the challenges and limitations of medical research study and the value of determination and continued efforts in finding efficient solutions for avoiding and treating illness.