| Abstract: | In an attempt to improve the serological response of infants in warm climates to oral poliovirus vaccine (OPV), the authors administered to 79 children between 6 and 41 weeks of age trivalent and monovalent OPV containing a virus dose 10 times as high as that found in the standard vaccine. The seroconversion rates following one dose of this trivalent OPV were 42% to type 1 poliovirus, 85% to type 2, and 31% to type 3. These rates are only slightly better than those previously reported after one dose of standard trivalent OPV and much lower than those achieved after 3 doses. The seroconversion rates following one dose of the monovalent OPV of enhanced potency were 89%, 93%, and 76%, respectively. These rates are comparable to those achieved after 5 doses of the standard trivalent OPV. Thus the refractoriness of host response was only partly overcome by enhancing the virus inoculum 10-fold. |
