In the years 1938-1944, with Paul Giroud he studied the adaptation of Rickettsia prowazekii, the agent responsible for typhus, by the inoculation of a rabbit by the respiratory route.

[3][4] In 1964, he isolated with Claude Hannoun, Jean Mouchet and Jean-Pierre Eouzan the first strains of the West Nile virus in the Rhône delta of the Camargue in the south of France.

He defended his Medical Degree in September 1939,[12] a few days after Britain and France declared war on Germany following Poland invasion.

[14] At that time, the Pasteur Institute faced a sensitive issue : the German authorities requisitioned serums and vaccines while typhus raged in French prison camps in Germany.

[15] Upon his return to occupied Paris in May 1943, he participated in the subversive activities of the Wizard (Jean Millet/William Savy) network of the Special Operation Executive, and became an underground agent (P2) from March to September 1944.

[16] Wizard network tasks led to the identification of a secret ammunition dump containing 2,000 V1 rockets ready to fire in the stone quarries at St-Leu-d'Esserent, near Paris.

[17] He was entrusted in November 1944 the establishment of a medical service responsible for the reception of prisoners, deportees and refugees in Lille at the northern tip of France.

Recalled at his request in the Far East Expeditionary Force, he volunteered to participate in the reduction of one of the last pockets of Third Reich resistance along the Atlantic coast of France, in Royan.

He embarked as a lieutenant doctor on 5 November 1945 aboard the victory ship Kings Point Victory for Indochina where he was appointed chief medical officer of the Indochina-South military laboratory and head of the bacteriology laboratory of the Pasteur Institute in Saigon (currently Ho Chi Minh City).

He set up research laboratories and the production of yellow fever vaccine according to the method of Max Theiler, Nobel Prize in medicine in 1951.

A study commission for the reform of the Pasteur Institute, made of Elie Wollman, René Panthier and Bernard Virat was established.