Two decades of regional trends in vaccination completion and coverage among children aged 12-23 months: an analysis of the Uganda Demographic Health Survey data from 1995 to 2016.

BACKGROUND: Childhood vaccination is an important public health intervention but there is limited information on coverage, trends, and determinants of vaccination completion in Uganda at the regional level. We examined trends in regional vaccination coverage and established the determinants of vaccination completion among children aged 12-23 months in Uganda. METHODS: We analyzed data from the women's questionnaire for the 1995-2016 Uganda Demographic Health Survey (UDHS). Vaccine completion was defined as having received a dose of Bacillus-Calmette Guerin (BCG) vaccine; three doses of diphtheria, pertussis, and tetanus (DPT) vaccine; three doses of oral polio vaccine (OPV) (excluding OPV given at birth); and one dose of measles vaccine. We performed Chi-square tests to compare vaccination completion by socio-demographic factors stratified by 10 sub-regions: Eastern, East Central, Central 1, Central 2, Kampala, Karamoja, North, Western, West Nile, and Southwest. We performed logistic regression analysis for each of the regions to identify factors associated with vaccination completion at 5% level of statistical significance. RESULTS: Overall vaccination completion was 48.6% (95%CI, 47.2, 50.1) and ranged from 17.3% in Central 1 to 65.9% in Southwest. Vaccination completion rates declined significantly by 10.4% (95% confidence interval (CI), - 16.1, - 4.6) between 1995 and 2000, and increased significantly by 10.0% (95% CI, 4.6, 15.4) between 2000 and 2006, and by 5.4% (95% CI, 0.2, 10.6) between 2006 and 2011. Maternal education (secondary or higher level), receipt of tetanus toxoid (TT) during pregnancy, and possession of a child health card were associated with vaccination completion across all the sub-regions. Other factors like place of residence, religious affiliation, household wealth, maternal age, childbirth order, size of child at birth, and place of delivery were associated with vaccination completion but differed between the 10 sub-regions. CONCLUSION: Besides considerable regional variations, the vaccination completion rate among children aged 12-23 months in Uganda remains suboptimal despite the availability of vaccines. Maternal education, receipt of TT, and possession of a child health card are associated with a higher likelihood of vaccination completion among children aged 12-23 months in all the regions of Uganda. Interventions to improve the utilization of vaccination services in Uganda should consider these factors.

Profile of immunologic recovery in HIV-infected Ugandan adults after antiretroviral therapy.

HIV infection is characterized by a decrease in total CD4 cell count, rising viral load, as well as an increase in immune activation levels. Increased activation can lead to an increase in apoptosis and contribute to CD4 depletion. We evaluated the clinical and immunologic responses of 23 HIV-positive Ugandan volunteers following initiation of antiretroviral therapy (ART). All volunteers achieved and maintained complete viral suppression within the first 3 months of therapy (p > 0.05). CD4+ and CD8+ T cell activation also decreased significantly, although it never reached the level of HIV negative Ugandan volunteers. Viral suppression and CD4 cell recovery were also associated with an improved profile in CD8+ T cell functional markers, but had no effect on HIV-specific proliferation. We conclude that ART in a cohort of therapy-naive Ugandans with AIDS partially restores but does not fully reverse the immune dysfunction observed in chronic HIV infection.

Presence of distinct subsets of cytolytic CD8+ T cells in chronic HIV infection.

Cytolytic T lymphocytes (CTL) play an important role in the control of HIV infection. The eventual failure to contain HIV-1 infection may arise because of a functional impairment of HIV-specific CTL. We evaluated Gag-specific cytotoxicity in HIV-1-positive Ugandans. Expression of CD107, a marker for cytolytic activity, was present in CD45RA(bright) and CD45RA(dim) CD8(+) T cell populations in HIV-infected individuals. The frequency of Gag-specific CD107(+)CD45RA(bright)CD28(-)CCR7(-) CD8(+) T cells decreased with CD4 cell depletion and correlated with the presence of Gag-specific T helper response. In contrast, the frequency of Gag-specific CD107(+)CD45RA(dim)CD28(-)CCR7(-) CD8(+) T cells within the same individuals has no significant association with viral load or CD4 cell count. The ratio of CD45RA(bright) to CD45RA(dim) CTL correlates significantly with CD4 cell count. This positive association decreases with antiretroviral treatment (ARV), indicating that suppression of viral replication alters the balance of circulating Gag-specific CD8(+) effector T cells. Subsets of cytolytic T cells may have distinct antiviral functions and further characterization of these effector CD8(+) T cells may yield important information on T cell regulation and dysfunction in HIV infection.

Pattern of malaria-specific T-cell responses in a cohort of Ugandan children.

Malaria is the leading cause of morbidity and mortality in children in Uganda. The mechanisms whereby malaria parasites are eliminated, or how they may avoid the immune response remain poorly understood. We examined malaria-specific T-cell responses in a well-characterized cohort of African children in an endemic area where malaria transmission occurs throughout the year. In studies of asymptomatic children, we found a low frequency of malaria-specific T-cell responses (15/117), and these appeared to be clustered in older children (> or =4 years old). Both CD4- and CD8-mediated T-cell responses were detected against circumsporozoite surface protein (CSP) and merozoite surface protein-1 (MSP-1). The presence of these T cells did not correlate with the frequency of prior episodes of parasitemia and 5 out of the 15 responders had no documented parasitemia within 8-12 months prior to immunologic evaluation. Our data supports focusing on high-risk children in future preventive vaccination efforts to ensure the generation and maintenance of effective anti-malarial cellular immune responses.