Rosenfeld, a Jew born in Lemberg, the Austro-Hungarian Empire (today Lviv, Ukraine), was raised in Wöllersdorf near Wiener Neustadt. He graduated in medicine with specialization in urology from Vienna University. After the Anschluss, Rosenfeld was deported to Dachau concentration camp and later to Buchenwald. In 1939 he was released and had to leave the country within two weeks. Since China did not require Jews to apply for a visa, he fled to Shanghai.
Since 1941 he served the Chinese Communist force as a field doctor for the New Fourth Army, the Eighth Route Army and the Northeast People's Liberation Army during the outbreak of Second Sino-Japanese war and Chinese civil war. He chose to remain in China after the fall of the Nazi regime and participated in the People's Liberation Army's march on Beijing before returning to Europe to search for relatives in 1949, the year the People's Republic of China was founded.