Beginning in the 1940s Chumakov organized multiple medical expeditions to Siberia and other regions of the Soviet Union to investigate outbreaks caused by new viruses.

In 1952 as a part of the anti-Semitic campaign in the Soviet Union known as Doctors' plot he was removed from the Ivanovsky Institute for refusal to fire Jewish associates.

[3] In 1958-1959 he and his wife Marina Voroshilova organized the first mass production and clinical trials of Oral Poliovirus Vaccine (OPV)[4] made from live attenuated strains developed by Albert Sabin.

The vaccine produced by Chumakov's Institute was exported into more than 60 countries, and was instrumental in stopping large outbreaks of poliomyelitis in Eastern Europe and Japan.

The success of the Russian clinical trials was critical to OPV licensing in the United States in 1962, and the vaccine becoming the main tool used in global poliomyelitis eradication campaign.