Bordetella pertussis: Vaccine Coverage and Immune Status among Children Under Five Years Old in Sana’a City, Yemen

Abstract

Aims:This study was made to evaluate the immune response to pertussis among children under five years old by measuring the level of circulating Immunoglobulin G (IgG) antibodies against pertussis toxin (IgG-PT) after immunization with the primary series of DPT (DPT1-3) and then determining the coverage rates of universal childhood vaccines. Study Design: Cross-sectional laboratory study. Place and Duration of Study: Methodology: A total of 345 children were randomly selected and investigated for universal childhood vaccination coverage rates; of these, 273 children who had received 3 full doses of DPT were studied for their pertussis immunological status. Blood samples were collected from the latter group and then tested for levels of IgG-PT by ELISA method. For assessment IgG-PT levels more than 24 units/ml were considered protected against pertussis. Data were analyzed according to Al-Shamahy and Al-Wafi; IJTDH, 35(3): 1-7, 2019; Article no.IJTDH.8143 2 gender and age groups. Results: The coverage rate of pertussis vaccine was 79.1%; only 71.4% of vaccinated children responded to the vaccine with mean level of 33 U/ml. A statistically significant difference was observed with respect to sero-protective IgG-PT between males and females (63.8% and 84.8% respectively, with χ 2 =15, p=0.0001). Also, a statistically significant difference was observed with respect to sero-protective IgG-PT in different age groups, with older children (>48 months) having a higher rate of antibodies than younger (13-24 months) (90% and 59.1% respectively, with χ 2 =3.87, p=.04). Original Research Article Conclusion:We conclude that a considerable proportion of vaccinated children with a normal immune status were not serologically immune to pertussis. They remain to be reconsidered for either revaccination or booster doses due to lack of or inadequate response. Also, the rates of vaccine coverage for the main universal childhood vaccines are low.

Evaluation of response to hepatitis B vaccine in iranian 6–18-year-old students

“…Reports of the Center for Diseases Control and Prevention[ 23 ] and American Academy of Pediatrics Infectious Diseases[ 24 ] showed that three times infusion of HBV vaccine caused the occurrence of protective antibody in 85%–100% of people which was higher than our report. The levels of immunity against vaccination with recombinant hepatitis B vaccine in a study which was conducted in Yemen[ 25 ] and those of Iran[ 26 27 28 ] had ranges of 50%–80% which was higher than our findings. Several studies have been reported that immune response to hepatitis B vaccine is depended on host factors such as sex, age, weight, genetics, and immunocompetent of individuals.…”

Assessment of Immunization to Hepatitis B Vaccine among Children under Five Years in Rural Areas of Taiz, Yemen

“…The low correlation value was due to the weaker protective response of the one to <2 years old group compared to the older age group. This finding was supported by previous reports of declined HBV vaccine protective level with age in Yemen [13, 19]. Similar association between older age and lower level of HBV vaccine protection rate has been reported by studies conducted in Saudi Arabia [36], Europe [37], and China [38, 39].…”

“…This HBV vaccine seroprotective rate was higher than the rate reported in children <1–10 years old by Al Shamahy and coworkers in Sana'a 5 years ago [13]. However, it was lower than that reported by Sallam and coworkers from Sana'a in 2005 [20].…”

“…Natural immunity to HBV infection was first excluded by screening for total anti-HB core antibodies as previously described [13]. One child who had anti-HB core antibodies was excluded from study.…”

“…With the availability of HBV vaccine since 1982, the decline in the incidence of HBV infection and associated morbidity and mortality has been reported in Taiwan and the United States [ 11 , 12 ]. In 1998, the World Health Organization (WHO) recommended the inclusion of HBV vaccine in the national immunization program of Yemen particularly among neonates, where vertical transmission is common, regardless of the prevalence of circulating HBsAg [ 13 ]. Despite a remarkable success in immunization coverage in Yemen, there are still areas of low coverage and a gap still exists between urban and rural areas.…”