The vaccination rate against COVID-19 remains low in developing countries due to vaccine hesitancy. Vaccine hesitancy is a public health threat in curbing COVID-19 pandemic globally. Healthcare professionals have been found to play a critical role in vaccine advocacy and promotion campaigns in the general population. A cross sectional study was conducted in the initial months of the COVID-19 vaccination roll out program in Tanzania to determine the acceptance rate, perceived barriers, and cues for actions. A total of 811 healthcare professionals participated from 26 health facilities in western Tanzania. The World Health Organization (WHO) vaccine acceptance questionnaire was adopted with minor modifications to capture the local contexts and used in data collection. Only (18.5%) healthcare professionals had received a COVID-19 vaccine and acceptance rate was 29%. The majority (62%) of participants were in the hesitancy stage due to issues related to lack of effective communication and reliable information regarding efficacy and safety. In this era of COVID-19 pandemic, there is a need to engage and involve public health figures and opinion leaders through transparent dialogue to clarify vaccine-related safety, quality, and efficacy. These strategies will reduce misconception, mistrust, and improve uptake among healthcare professionals and eventually in the general population.

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.

Leptospirosis is a zoonotic neglected tropical disease with a worldwide distribution caused by the pathogenic spirochetes of the genus Leptospira. Despite being a widespread disease in tropical regions, it has never been considered in the routine diagnostic panel for febrile patients. This study determined seropositivity and factors associated with Leptospira antibodies among febrile adult patients in Mwanza, Tanzania. The cross-sectional study involving 296 febrile patients attending different outpatient clinics in Mwanza region was conducted between May and July 2019. Detection of Leptospira serovars antibodies was done using a microscopic agglutination test (MAT). Descriptive analysis was done using STATA version 13. The median age of the febrile patients was 32 (IQR: 24–45 years). Out of 296 patients, 36 (12.16%, 95%CI: 8–15) were seropositive for Leptospira antibodies. Common circulating serovars were Sokoine 28 (9.45%), followed by Lora 12 (4.05%) and Grippotyphosa 2 (0.67%). In the multivariable logistic regression analysis, the odds of being Leptospira seropositive were significantly higher with increased age (aOR: 1.03, 95%CI 1.00–1.07, p = 0.03). About one tenth of febrile patients in Mwanza were seropositive for Leptospira antibodies and this was significantly associated with age. With the decline of malaria fever in endemic areas, other causes of febrile illness like Leptospiral spp. should be considered in the routine diagnostic panel for febrile patients.

COVID-19 vaccination remains to be the most important intervention in the fight against the pandemic. The immunity among the vaccinated population and its durability can significantly vary due to various factors. This study investigated the humoral immune responses among individuals who received any of the COVID-19 vaccines approved for use in Tanzania. A total of 1048 randomly selected adults who received COVID-19 vaccines at different time points were enrolled and humoral immune responses (IR) were tested at baseline and three months later (960, 91.6%). The level of SARS-CoV-2 anti-spike/receptor binding domain (RBD) IgG, anti-nucleocapsid IgG, and IgM antibodies were determined using a commercially available chemiluminescent microparticle immunoassay. Descriptive data analysis was performed using STATA version 18 and R. At baseline, serum IgG against anti-spike/RBD was detected in 1010/1048 (96.4%) participants (95%CI: 94.9–97.5) and 98.3% (95%CI: 97.3–99) three months later. The IgG against the SARS-CoV-2 nucleocapsid proteins were detected in 40.8% and 45.3% of participants at baseline and follow-up, respectively. The proportion of seroconverters following vaccination and mean titers of anti-spike/RBD antibodies were significantly more among those who had past SARS-CoV-2 infection than in those with no evidence of past infection, (p < 0.001). Only 0.5% of those who had detectable anti-spike/RBD antibodies at baseline were negative after three months of follow-up and 1.5% had breakthrough infections. The majority of participants (99.5%) had detectable anti-spike/RBD antibodies beyond 6 months post-vaccination. The proportion of Tanzanians who mounted humoral IR following COVID-19 vaccination was very high. Seroconversions, as well as the mean titers and durability of humoral IR, were significantly enhanced by exposure to natural SARS-CoV-2 infection. In view of the limited availability of COVID-19 vaccines as well as challenges to completing subsequent doses, booster doses could only be suggested to high-risk groups.