Small-scale Trial with Sabin Attenuated Type 1 Poliovirus Vaccine in a Semi-closed Community

The desirable properties of a live poliovirus vaccine are that it should be of attenuated neurovirulence, be genetically stable during growth in the human intestine, and so be safe for the vaccinated individual and the community. It should moreover be able to infect the alimentary tract readily, and elicit an antibody response after such infection (W.H.O., 1960). Although the vaccine viruses developed by Sabin appear to possess most of these qualities, it is known that intestinal passage may give rise to some variation. Nevertheless, no serious consequences have been reported amongst the 100 millions or so that have now received Sabin attenuated vaccine in many parts of the world. A small- scale study with the Sabin type 3 virus has already been reported from Shefflield (Clarke et al., 1958), and the present trial was performed with type 1 vaccine to obtain information about: (1) the spread, within a poliovirus- free semi-closed community, after infection of a number of children with a single dose of living type 1 polio- virus vaccine; (2) the degree and duration of virus excretion; (3) the serological response to vaccination; and (4) the genetic stability of the vaccine virus strain on passage through the human gut. The virus used was the living, attenuated, L Sc, 2ab type 1 vaccine developed by Sabin, and received from him in 1959 in the form of infected monkey-kidney-tissue culture fluid. Since 1959 it had been stored at -70C.