Trends of measles in Tanzania: A 5-year review of case-based surveillance data, 2018-2022.

OBJECTIVES: Tanzania observed a gradual increase in the number of measles cases since 2019 with a large outbreak recorded during 2022. This study describes the trend of measles in Tanzania over a 5-year period from 2018-2022. METHODS: This was a descriptive study conducted using routine measles case-based surveillance system including 195 councils of the United Republic of Tanzania. RESULTS: Between 2018 and 2022 there were 12,253 measles cases reported. Out of 10,691 (87.25%) samples tested by enzyme-linked immunosorbent assay, 903 (8.4%) were measles immunoglobulin M positive. The highest number of laboratory-confirmed measles cases was in 2022 (64.8%), followed by 2020 (13.8%), and 2019 (13.5%). Out of 1279 unvaccinated cases, 213 (16.7%) were laboratory-confirmed measles cases compared to 77/723 (10.6%) who were partially vaccinated and 71/1121 (6.3%) who were fully vaccinated (P < 0.001). Children aged between 1-4 years constituted the most confirmed measles cases after laboratory testing, followed by those aged 5-9 years. There was a notable increase in the number of laboratory-confirmed measles cases in children <1 year and 10-14 years during 2022 compared to previous years. The vaccination coverage of the first dose of measles-containing vaccine (MCV1) was maintained >90% since 2013 while MCV2 increased gradually reaching 88% in 2022. CONCLUSIONS: Accumulation of susceptible children to measles due to suboptimal measles vaccination coverage over the years has resulted in an increase in the number of laboratory-confirmed measles cases in Tanzania with more cases recorded during the COVID-19 pandemic. Strengthening surveillance, routine immunization, and targeted strategies are key to achieving the immunity levels required to interrupt measles outbreaks.

Rotavirus genotype diversity in Tanzania during Rotavirus vaccine implementation between 2013 and 2018.

The study aims to determine Rotavirus genotypes between 2013 and 2018 during implementation of ROTARIX vaccine in Tanzania. The analysis of surveillance data obtained between 2013 and 2018 was done to determine circulating genotypes after introduction of Rotarix vaccine. From 2013 to 2018, a total of 10,557 samples were collected and screened for Rotavirus using an enzyme immunoassay. A significant decrease in Rotavirus positivity (29.3% to 17.8%) from 2013 to 2018 (OR 0.830, 95% CI 0.803-0.857, P < 0.001) was observed. A total of 766 randomly selected Rotavirus positive samples were genotyped. Between 2013 and 2018, a total of 18 Rotavirus genotypes were detected with G1P [8] being the most prevalent. The G1P [8] strain was found to decrease from 72.3% in 2015 to 13.5% in 2018 while the G9P [4] strain increased from 1 to 67.7% in the same years. G2P [4] was found to decrease from 59.7% in 2013 to 6.8% in 2018 while G3P [6] decreased from 11.2% in 2014 to 4.1% in 2018. The data has clearly demonstrated that ROTARIX vaccine has provided protection to varieties of the wild-type Rotavirus strains. Continuous surveillance is needed to monitor the circulation of Rotavirus strains during this era of vaccine implementation.

Reduction in Rubella Virus Active Cases among Children and Adolescents after Rubella Vaccine Implementation in Tanzania: A Call for Sustained High Vaccination Coverage.

Rubella virus (RV) infection in susceptible women during the first trimester of pregnancy is associated with congenital Rubella syndrome (CRS). In countries where a vaccination program is implemented, active case surveillance is emphasized. This report documents the magnitude of active cases before and after vaccine implementation in Tanzania. A total of 8750 children and adolescents with signs and symptoms of RV infection were tested for Rubella IgM antibodies between 2013 and 2019 using enzyme immunoassay followed by descriptive analysis. The median age of participants was 3.8 (IQR: 2−6.4) years. About half (4867; 55.6%) of the participants were aged 1−5 years. The prevalence of RV active cases was 534 (32.6%, 95% CI: 30.2−34.9) and 219 (3.2%, 95% CI: 2.7−3.6) before and after vaccine implementation, respectively. Before vaccination, the highest prevalence was recorded in Pemba (78.6%) and the lowest was reported in Geita (15.6%), whereas, after vaccination, the prevalence ranged between 0.5% in Iringa and 6.5% in Pemba. Overall, >50% of the regions had a >90% reduction in active cases. The significant reduction in active cases after vaccine implementation in Tanzania underscores the need to sustain high vaccination coverage to prevent active infections and eventually eliminate CRS, which is the main goal of Rubella vaccine implementation.

Domestic funding opportunities for Tanzania as five new Middle-Income countries brace for reduced Gavi support for immunization.

Vaccines have produced remarkable impact in reducing the global burden of disease. Thanks to Gavi-the Vaccine Alliance, which supports eligible countries to increase access to the new and underused vaccines. Gavi support depends on economic growth, whereby low-income countries contribute 0.2 USD per dose of supported vaccines, while middle-income countries contribute by price fraction that increases gradually by 15% annually. A country must become fully self-financing within five years when its economy reaches 1,630 USD GNI per capita. Recently, Tanzania, Benin, Haiti, Nepal, and Tajikistan became middle-income countries triggering gradual reduction in Gavi support. This paper first compares the socio-demographic characteristics, immunization program performance, and health financing strategies of these countries and second, explores domestic financing strategies that Tanzania can use to close the funding gap. Although the five countries are similar economically, they vary in demography, health financing strategies, extent of donor dependency, and strength of immunization programs. Some health indicators are not any better than those in low-income countries. Tanzania receives the largest financial support from Gavi and is projected to be fully self-financing by 2043. The potential domestic funding opportunities include to increase Government budget, use of innovative financing strategies, and health insurance, complemented with enhanced program efficiency.

Factors associated with non-uptake of measles-rubella vaccine second dose among children under five years in Mtwara district council, Tanzania, 2017.

INTRODUCTION: in 2014, Tanzania introduced the combined measles-rubella vaccine in the routine immunization schedule. Two doses of measles-rubella vaccine (MR1 and MR2) are recommended at 9 and 18 months, respectively. In 2015, MR2 coverage among eligible 18-month-old children in Tanzania was only 57%, lower than the WHO-recommended coverage (95%). During the same period Mtwara District Council (MDC) reported a coverage of 52% which is lower than the nation average. We determined factors associated with non-uptake of MR2 among children in MDC Tanzania. METHODS: we conducted a community-based cross-sectional survey using cluster sampling during January - April 2017 in MDC. Caretakers of children born during January 2014 - January 2015 and residing in MDC for the past three years were recruited. We interviewed participants and reviewed vaccination cards. Logistic regression modeling was employed to identify independent factors associated with uptake of MR2. RESULTS: of 1,000 children assessed, 558 (55.8%) were unvaccinated with MR2. Factors independently associated with non-uptake of MR2 included the caretaker being unaware of the ages for MR1 and MR2 administration [aOR=3.50; 95%CI 1.98-6.21; p<0.001], having MR2 vaccination services offered at the local vaccination station fewer than three days per week [aOR=1.50; 95%CI 1.42-5.59; p<0.001], not having the vaccine available during vaccination days [aOR=3.38; 95%CI 1.08-10.61; p<0.01], unwillingness of health workers to open multi-dose vaccine vials for a single child [aOR=3.80; 95% CI 2.12-6.79; p<0.001], and long waiting times for vaccination services [aOR=1.80; 95% CI 1.08-3.00; p<0.01]. CONCLUSION: more than half the children under five years in MDC were not vaccinated with MR2. Lack of caretaker knowledge about appropriate vaccination age, unavailability of vaccine, having insufficient numbers of children waiting to warrant multidose vial use, and long clinic waiting times were associated with MR2 non-uptake. The community should receive education about MR vaccine; we recommend thorough screening of children?s vaccination status at each clinic visit and provision of vaccine whenever possible. Vaccine distribution should be improved in MDC.