Tetanus antibody levels among adolescent girls in developing countries

Immunity status against tetanus in young migrants: a seroprevalence study

BACKGROUND AND AIM OF THE WORK

Thanks to the highly effective vaccine, tetanus became sporadic in high-income countries with well-established primary childhood immunization programs, but it is common in low-income countries. The migrants, leaving countries with poor immunization programs or where vaccinations have been interrupted, may represent a new risk group for tetanus in host countries. A seroprevalence study was conducted to estimate the immunological status against tetanus in young migrants without vaccination documentation.

METHODS

After a careful assessment by vaccination services of the Local Health Authority, all migrants recently arrived in Italy were included in the serosurvey. Titers of anti-tetanus toxoid were measured using a commercial ELISA kit. Subjects were stratified by age and by WHO region. Antibody titers <0.10 IU/ml were considered to be seronegative, between 0.10 and 1.00 IU/ml as intermediate protection, and >1.00 IU/ml high protection.

RESULTS

From January 2004 to December 2019, 2,326 blood samples were collected. Mean age was 13.9 years with no differences between WHO regions. The percentage of the subjects without protective antibodies was 22.3%, with an intermediate level was 45.2%, with high titer was 32.5%. Among migrant coming from African and Eastern Mediterranean WHO regions, the highest percentages of seronegative titers and, at the same time, the low percentages of high protective levels were found. Titers decreased with age.

CONCLUSIONS

The significant proportion of seronegative migrants and the decrease of protective titers increasing age, confirm the importance of the evaluation of the immunological status to employ the appropriate vaccination strategy.

The state of adolescent immunization in Nigeria: a wake up call for all stakeholders

The number of children who survive to adolescence is increasing in Nigeria, significantly due to the success of child survival programs, with immunization as a major theme. However, the national immunization schedule in Nigeria is presently restricted to early childhood with no attention paid to immunization in adolescence. Presently, the vaccines that are readily available for adolescents include tetanus toxoid which is normally administered to pregnant women, so necessarily includes adolescent mothers; and a few research programs which offers hepatitis B vaccines. Also, there are few Nigerian adolescents who access immunization as a requirement for travelling outside the country or as a result of parental effort. Knowledge and awareness about adolescent immunization is generally poor. Nigerian adolescents have been shown to be poorly protected from tetanus, rubella and hepatitis B which are vaccine preventable. Neonatal, childhood and adult tetanus, congenital rubella syndrome, cervical cancer and hepatocellular carcinoma are just few of the diseases whose incidence can be reduced with an effective adolescent immunization program. This will also ensure that the gains of childhood immunization is concretized and socio-economic losses as a result of vaccine preventable diseases are eliminated to create a healthy and vibrant workforce. There is an urgent need to build a viable adolescent immunization program in Nigeria as adolescents represent a window of opportunity to prevent diseases which affect both the younger and older age group. This can be extended to other developing countries as well.

Maternal and neonatal tetanus

Maternal and neonatal tetanus is still a substantial but preventable cause of mortality in many developing countries. Case fatality from these diseases remains high and treatment is limited by scarcity of resources and effective drug treatments. The Maternal and Neonatal Tetanus Elimination Initiative, launched by WHO and its partners, has made substantial progress in eliminating maternal and neonatal tetanus. Sustained emphasis on improvement of vaccination coverage, birth hygiene, and surveillance, with specific approaches in high-risk areas, has meant that the incidence of the disease continues to fall. Despite this progress, an estimated 58,000 neonates and an unknown number of mothers die every year from tetanus. As of June, 2014, 24 countries are still to eliminate the disease. Maintenance of elimination needs ongoing vaccination programmes and improved public health infrastructure.

Prevalence and socio-demographic factors associated with non-protective immunity against tetanus among high school adolescents girls in Nigeria

BACKGROUND

The low uptake of tetanus vaccine and its resultant high burden of tetanus in Nigeria suggest the need to improve routine and booster vaccination in children and adolescents. However, epidemiological evidence for vaccination in the adolescent age group needed for effective strategy and policy formulation is lacking. This study was carried out to determine the prevalence of protective immunity against tetanus and to identify risk factors for non-protective immunity among schooling adolescents.

METHODS

Using a three-stage sampling technique, 851 female adolescents were randomly selected from secondary schools in Ibadan, Nigeria. A pre-tested questionnaire was used to obtain data on demographic and socio-economic characteristics and history of tetanus vaccination. An immuno-chromatographic rapid test kit, "Tetanos Quick Stick" was used to test specific anti-tetanus antibody protective level in venous blood samples. Descriptive statistics, Chi-square and logistic regression analyses were done with level of significance set at p = 0.05.

RESULTS

Mean age of participants was 14.3 ± 1.9 years. Seroprevalence of protective immunity against tetanus was 38.1% and it significantly decreased with increasing age. More adolescents in public (65.4%) than private (44.7%) schools had non-protective level of immunity. A significantly increasing trend in the risk of non-protective immunity was observed with decreasing level of mothers' education. Also, the Odds of non-protective level of immunity was significantly higher in public than private schools (OR = 2.14; 95% CI =1.39, 3.20) but lower among adolescents who had history of recent tetanus toxoid injection than those who did not (OR = 0.11 95% CI = 0.09, 0.22). However, no significant association was found between protective immunity against tetanus and parents' marital status as well as family size.

CONCLUSION

Protective immunity against tetanus among female adolescents was poor, more so in public schools and those who had not received vaccination a year prior to the study. Policy-makers need to consider the inclusion of immunization against tetanus in the school health programme.

Immunity Against Tetanus Infection, Risk Factors for Non-Protection, and Validation of a Rapid Immunotest Kit among Hospitalized Children in Nigeria

Seroepidemiological studies of tetanus in Africans have focused mainly on adults especially pregnant women and data on children are scarcely reported. We investigated the seroprevalence of protective immunity level, determined risk factors for non-protection against tetanus, and evaluated the performance of Tetanos Quick Stick^® (TQS) among hospitalized children aged 1–9 years in Nigeria. Blood IgG antibody levels to tetanus was determined using enzyme-linked immunosorbent assay (ELISA) in the laboratory and TQS (an immunochromatographic test) at the bedside for 304 children admitted into emergency unit of a tertiary hospital in Ibadan, Nigeria. Demographic information and vaccination history were also collected. TQS results were compared with anti-tetanus antibody measured by ELISA using seroprotection cut-off of 0.1 IU/ml. Seroprevalence of protective level of immunity against tetanus using ELISA and TQS methods was 44.7 and 45.4% respectively. Protective level of immunity increased as age increases. Of the seven potential factors assessed, male gender and being second or more position among mother’s children were independent predictors of non-protective level of immunity. Absence of history of recent tetanus toxoid injection was significantly associated with non-protective level of immunity in univariate analysis but not logistic regression model. The agreement between the ELISA and the TQS results was good with a k coefficient of 0.931. TQS sensitivity was 95.7%, specificity 97.6%, positive predictive value 98.0%, and negative predictive values 96.0%. This study showed that lack of protective immunity against tetanus is common; few demographic characteristics correctly predict non-protection and IgG antibody levels to tetanus was accurately detected by TQS.

Frequent failure of adolescent booster responses to tetanus toxoid despite infant immunization: waning of infancy-induced immune memory?

To define the capacity of a tetanus toxoid booster to reactivate infant-triggered immunity, anti-tetanus antibodies were assessed before and after boosting 162 adolescents and 219 children from Mfou (Cameroon). Among 63 adolescents with 3 recorded dose of infant DTP, 29/63 (46%) responded with a > or =4-fold increase of antibody titers, 35/63 (55%) reaching the 0.10UI/ml threshold. Response rates were slightly higher (62%) in children aged 10-11 years. Responders and non-responders only differed significantly in their baseline anti-tetanus antibodies. Thus, early life immune immaturity may limit the persistence of infant-induced immunity and subsequent boosters may be required for sustained protection.

Determination of tetanus antibodies by a double-antigen enzyme-linked immunosorbent assay in individuals of various age groups

In this study, tetanus immunity was determined in 549 randomly chosen individuals of various age groups in Ankara, Turkey. Antibody levels in sera of the individuals were measured using a double-antigen enzyme-linked immunosorbent assay. Overall, 66.5% (95%CI, 62.4-70.4) of the population studied was found to have basic protection (>or=0.01 IU/ml) against tetanus. Protective levels of tetanus antibodies declined progressively with age. The rate of protection in children and adolescents (aged<20 years) exceeded 90%, while only 16.3% (95%CI, 8.9-26.2) of those over 60 years of age were protected. Females over 60 years of age were less immune than males of the same age group (p=0.034). Although the rates of protection in children and adolescents are regarded as satisfactory, the rates among adults are low. Preventive measures against tetanus should therefore focus on scheduled booster immunization for adults as well as children.

EPI vaccines-induced antibody prevalence in 8-9 year-olds in The Gambia

OBJECTIVES

We evaluated antibody prevalence to measles, polio 1 and 3, and tetanus toxoid antibodies in 8-9 year-old children in The Gambia within the framework of the Gambia Hepatitis Intervention Study (GHIS), a large vaccine trial aimed at evaluating vaccine efficacy against hepatitis B virus (HBV) infection, chronic carriage and primary liver cancer in a high risk population. The results of the present survey were compared with a previous survey performed with the same objectives and same methodology but in different children at 3-4 years of age.

METHODS

Four clusters of 200 children each were sampled as representative of the whole country. Children would have received BCG, diphtheria-pertussis-tetanus vaccine (DPT), poliovirus vaccine (OPV), measles and yellow fever immunization. The measles haemoagglutination inhibition test (HAI) was used to detect measles antibody. Antibodies to polioviruses 1 and 3 were tested using the standard polio neutralization assay described in the EPI manual (WHO 1990). An enzyme-linked immuno-sorbent assay (ELISA) was used to measure tetanus toxoid antibodies.

RESULTS

A high proportion of children were fully vaccinated in both age groups. Measles antibody concentrations were < or =1 : 8 in 8.2% of 8-9 year-old vaccinated children. In the previous survey of 3-4 year-old children this was 11.3%. In the present survey, GMC was lower than in the 3-4 year-old children; 88% of 3-4 year-olds and 89% of 8-9 year-olds had detectable antibody levels against poliovirus type 1. Fewer children at 8-9 years of age had antibodies against poliovirus type 3 than 3-4 year-olds (78%vs. 89% P < 0.001). A significant overall lower proportion of 8-9 year-old children had detectable tetanus toxoid antibodies compared to 3-4 year-old children (87%vs. 95% P < 0.001), as well as those who received four doses of DPT (90%vs. 97% P < 0.001). Conclusions High vaccine coverage is achieved in The Gambia with EPI. With time the number of vaccinated children who are not protected against measles, poliovirus 3 and tetanus increases. Besides the maintenance of high vaccine coverage in infants and young children, booster doses of some of the EPI vaccines in adolescents should be considered.

Adolescent vaccination in the developing world: time for serious consideration?

The number of vaccinations and vaccine boosters that are becoming relevant to delivery among adolescents is growing. For sexually transmitted infections (STIs) in particular, such as HIV, vaccine delivery in this (pre-sexually active) age group is going to be an integral component of the strategy to control these diseases in the future. Currently, however, adolescent vaccination does not routinely occur because the traditional method of delivery is through secondary schools, and in developing countries school attendance has historically been low. But with school attendance growing rapidly throughout the developing world, the cost of vaccines falling over time, and an increasing number of current and future vaccines targeted at adolescents, it is an ideal opportunity to place this route of delivery on the national and international health agenda. Therefore, this paper examines the rationale for adolescent vaccination, looks at the success of other adolescent-targeted health care interventions, and finally, considers the challenges associated with future adolescent vaccination programmes in developing countries.