Browsing by Author "Adu, F. D."

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    Low level of pre-vaccination measles antibody among infants receiving measles immunization in ilorin, Kwara state, Nigeria
    (Multidisciplinary Digital publishing Institute (MDPI), 2013) Fowotade, A.; Okonko, I. O.; Nwabuisi, C.; Fadeyi, A.; Bakare, R. A.; Adu, F. D.
    This study was designed to assess the low levels of pre-vaccination measles antibody among infants receiving measles immunization in Ilorin, Kwara State, Nigeria. Pre-vaccination blood samples were obtained from 400 infants brought to the EPI Clinic of the University of Ilorin Teaching Hospital, Ilorin, Nigeria. Blood samples were collected by finger puncture onto ROPACO (Rochester, USA) rectangular filter paper measuring 7 cm by 10 cm. Other information like name, age, sex, date of vaccination was also recorded on the filter paper. The filter papers were dried at ambient temperature and stored in plastic bags at -20℃ until ready for serum extraction. Specimens were analyzed for measles antibody using Hemagglutination Inhibition technique. Data generated were subjected to Chi square statistical test to establish association between categorical variables with dichotomous outcomes. Of all the 400 infants screened for pre-vaccination measles antibodies, 29(7.2%) had protective antibody titer while 156 (39.0%) had low titer since ≥40 HI titer is the study threshold of protection against measles while 215(53.8%) had no detectable measles antibody titer (<1:10). Thirty-one (8.0%) of the infants had measles prior to vaccination. Previous history of measles was significant associated (P=0.0005, X2 = 34.507) with the level of pre-vaccination measles virus antibody. There was no significant difference (p=0.723) in the level of measles virus antibody among the exclusively breastfed infants and those that were not exclusively breast fed. Age (p=0.839) and sex (p=0.1999) were not significantly associated with the level of measles virus antibody. The distribution of this antibody levels appeared stable with no significant difference between age groups, sex and breast feeding pattern. Only the previous history of measles showed statistical association with measles virus antibody proportion. In conclusion, a larger proportion (53.8%) of the children had no detectable anti-measles virus antibody while 39.0% had low (non-protective) titer; these put both groups at risk of developing measles given the endemic nature of Nigeria. Therefore, re-evaluation of 9 months as the age for measles vaccination in Nigeria vis-à-vis 92.8% with <40 HI titer is highly recommended.
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    Measles vaccine potency and Sero- conversion rates among infants receiving measles immunization in Ilorin, Kwara state, Nigeria.
    (Taylor & Francis, 2014) Fowotade, A.; Okonko, I. O.; Nwabuisi, C.; Bakare, R. A.; Fadeyi, A.; Adu, F. D.
    This study was designed to assess the seroconversion rate of measles vaccine among infants receiving measles immunization in Ilorin, Nigeria. The pre- and post-measles vaccination sera of the children were tested using the Haemagglutination Inhibition test. The measles vaccines administered at the immunization centre were also tested for their potency using in-vitro titration method. Only 286 (71.5%) of the vacinees returned to give post-vaccination samples. All the infants screened had low pre-vaccination measles antibody titers. Thirty one (8.0%) of the infants had measles prior to vaccination. The seroconversion pattern showed that 196 (68.6%) of the infants developed protective antibody titers. Low seroconversion rate reported in this study was due to low vaccine potency. The titers of vaccines with low potency ranged between log10−1.0–log10−2.25 TCID/per dose. This was beside other non specific antiviral substances exhibited virus neutralizing activity. Only 3 (50%) of the 6 vaccine vials tested had virus titers of log10−3.25 to log10−3.5, which fell above the cut-off point recommended by the World Health Organization for measles vaccines. The sero-conversion rate of 68.6% observed among vaccinees is far lower than the immunity level of 95% required stopping measles transmission in an endemic community. Failure of 31.4% of these infants to sero-convert post vaccination can be attributed partly to administration of sub-potent vaccines. There is need for improvement and maintenance of effective vaccine cold chain system in Nigeria. There is need also for periodic monitoring of post-vaccination antibody titers as well as vaccine potency status in order to ensure development of protective seroconversion rates.