Background Substance use among school-going adolescents increases the risk of developing mental disorders, addiction, and substance use disorders. These may lead to poor academic performance and reduced productivity, which affects adolescent lives. The study aimed to determine the prevalence of substance use and associated factors among secondary school adolescents in the Kilimanjaro region, northern Tanzania. Methodology The study used secondary data from a cross-sectional survey of adolescents aged 10–19 years from public secondary schools in the Kilimanjaro Region, northern Tanzania. Substance use was measured using the Global School Health Survey (GSHS) questionnaire. Categorical variables were summarized using frequencies and percentages, while numerical variables used mean and standard deviation. Multivariable logistic regression models were used to obtain odds ratios (OR) and 95% confidence intervals (CI) to determine risk factors associated with lifetime and current (within the past 30 days preceding the survey) substance use. Results The lifetime and current prevalence of substance use among 3224 adolescents was 19.7% and 12.8%, respectively, while alcohol and cigarettes were commonly used. Female adolescents had lower odds of current substance use (OR = 0.63, 95%CI 0.50–0.80). Higher odds of current substance use were among adolescents who have ever had sex (OR = 4.31, 95%CI 3.25–5.71), ever engaged in a physical fight (OR = 2.19, 95%CI 1.73–2.78), ever been bullied (OR = 1.55, 95%CI 1.16–2.05), always seen alcohol advertisements (OR = 1.87, 95%CI 1.37–2.53), and adolescents whose parent/guardians rarely understood their problems (OR = 1.38, 95% CI = 1.03–1.85). Adolescents whose classmates always showed social support had lower odds of current substance use (AOR = 0.71, 95%CI 0.53–0.97). Similar factors were associated with lifetime substance users. Conclusion The study reflects a high prevalence of substance use among adolescents in the Kilimanjaro region. Alcohol and cigarette are the most prevalent substances used. Regulatory measures are essential to limit alcohol advertisements that are media portrayed. Efforts are needed to reduce risk behaviors, such as physical violence and bullying, through peer support groups/clubs in school environments.

The use of vaccines is one of the key tools in reversing the COVID-19 pandemic; however, various reports reported the low uptake of the vaccines. This study explored the barriers to the COVID-19 vaccine uptake among community members in Tanzania. A qualitative explorative study was conducted in December 2021 and April 2022 in eight regions of Tanzania. Focus group discussions (FGDs) and in-depth interviews (IDIs) were the methods of data collection. A total of 48 FGDs and 32 IDIs were conducted. Participants were aware of the COVID-19 disease and vaccines. The barriers to the COVID-19 vaccine non-uptake included receiving contradicting statements from top government leaders, vaccine preceded the education, myths towards vaccines, the presence of different types of vaccines, the process of getting the vaccine, the influence of social media and random people from the community, and vaccine conflicting religious beliefs. Despite being aware of the vaccine, the uptake of the COVID-19 vaccine is still low. Interventions that focus on increasing community knowledge about COVID-19 vaccines and addressing myths about the vaccines are needed.