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.

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.

Mumps is an acute contagious viral disease caused by paramyxovirus characterized by complications that include orchitis, oophoritis, aseptic meningitis, and spontaneous abortion among many others. This study reports high mumps IgG seropositivity among school-aged children in rural areas of the Mbeya region, information that might be useful in understanding the epidemiology of mumps and instituting appropriate control measures including vaccination. Between May and July 2023, a cross-sectional study involving 196 enrolled children aged 5–13 years was conducted. Sociodemographic information and other relevant information were collected using a structured data collection tool. Blood samples were collected and used to detect mumps immunoglobulin G antibodies using indirect enzyme-linked immunosorbent assay (ELISA). A descriptive analysis was performed using STATA version 15. The median age of the enrolled children was 13 (interquartile range (IQR): 8–13) years. The seropositivity of mumps IgG antibodies was 88.8% (174/196, 95% CI: 83.5–92.5). By multivariable logistic regression analysis, history of fever (OR: 5.36, 95% CI: 1.02–28.22, p = 0.047) and sharing utensils (OR: 8.05, 95% CI: 1.99–32.65, p = 0.003) independently predicted mumps IgG seropositivity. More than three-quarters of school-aged children in rural areas of the Mbeya region are mumps IgG-seropositive, which is significantly associated with the sharing of utensils and history of fever. This suggests that the virus is endemic in this region, which calls for further studies across the country so as to institute evidence-based, appropriate control measures including a vaccination program.

Globally, 24 measles virus genotypes have been detected, and these genotypes have been classified into eight clades based on 450 nucleotides of the C-terminal region of the nucleoprotein gene. Genotype B3 is predominant in Africa, but there are limited data from Tanzania since the introduction of the second dose of measles-containing vaccine in 2014. A total of 129 nasopharyngeal samples and corresponding sera were collected during measles outbreaks between 2022 and 2024. Viral RNA was extracted from nasopharyngeal swabs prior to RT-qPCR and sequencing of a 450-nucleotide segment of the nucleoprotein (N) gene. Out of 129 nasopharyngeal samples, 73 (56%) were successfully amplified and identified as endemic measles virus genotype B3. Nine distinct sequence identifiers were detected, with seven reported for the first time in the MeaNS database. All the Tanzanian B3 sequences were closely related and clustered with genotype B3, similar to those reported from Kenya, Ethiopia, Rwanda, Uganda, Burundi, and South Africa. On multivariate analysis, only inpatient admission status (p = 0.014) and positive measles IgM (p = 0.003) were found to be associated with positive measles RT-qPCR. Our results indicate that genotype B3 remains endemic in Tanzania and is closely related to other genotype B3 reported globally, indicating its high stability and transmissibility.