This image was created in October, 2014, by Centers for Disease Control and Prevention (CDC), Epidemiologist, Mary Alleman, M.P.H., Ph.D., and captured during an outbreak of wild poliovirus in the Central African nation of Cameroon, specifically, at a bus station in Bafoussam, the regional capital of West Region, Cameroon. The photograph depicts two vaccination team members on the right, one wearing a yellow apron, and one a yellow hat, as they were in the process of vaccinating a child, who had just exited an arriving bus. This child would have been missed by the primary vaccination strategy implemented by these campaigns, which involves vaccination teams going to door-to-door to vaccinate children at their homes. This was one of the entries in the 2015 CDC Connects, Public Health in Action Photo Contest.
In 2013 and 2014, Cameroon had an outbreak of wild poliovirus. One epidemiologic aspect of a poliovirus outbreak response, is to conduct polio vaccination campaigns with high coverage of the target population. One strategy for ensuring the highest possible vaccination coverage, is to have vaccination teams posted at places where the population congregates, for example bus stations, so that children in transit during the days of the campaign will have an opportunity to be vaccinated.
To read more about efforts being made to eradicate polio, see the link below.