Combined vaccination with live oral polio vaccine and the bovine rotavirus RIT 4237 strain

Abstract

A clinical trial was carried out in 3-month-old infants to assess whether concomitant oral administration of live polio and rotavirus RIT 4237 vaccines would reduce their immunogenicities as a result of mutual interference. One hundred and sixty breast-fed male and female infants were randomly allocated to four study groups to receive in a blind fashion the poliovirus vaccine, the RIT 4237 vaccine, a combination of both vaccines or a placebo preparation. Antibody titres were measured in pre- and postvaccination serum samples by the ELISA test and the neutralizing antibody test (NT) for rotavirus and by the NT for polioviruses types 1 and 3. The percentage of subjects with immune responses to rotavirus in the placebo group was low, indicating the absence of wild rotavirus circulation in the population. Antibody responses against polio types 1 and 3 were found in about a quarter of the infants receiving a placebo because the study was performed during a polio vaccination campaign when vaccine viruses are known to circulate. The results showed that 73% of seroconversion was obtained when RIT 4237 was administered alone and that the responses to polioviruses types 1 and 3 were good. However, simultaneous administration of polio and RIT 4237 vaccines caused a significant reduction of the antibody response to rotavirus but not to polioviruses types 1 and 3.