Coronavirus disease 2019 (COVID-19) has been extensively researched, particularly with regard to COVID-19 vaccines. However, issues with logistics and availability might cause delays in vaccination programs. Thus, the efficacy and safety of half-dose heterologous mRNA should be explored. This was an open-label observational study to evaluate the immunogenicity and safety of half-dose mRNA-1273 as a booster vaccine among adults aged >18 years who underwent a complete primary SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) vaccination regimen with CoronaVac^® and ChAdOx1-S. Adverse events (AEs), seropositivity rate, seroconversion, geometric mean titer (GMT) of SARS-CoV-2 antibodies, neutralizing antibodies, and T cells (CD4+ and CD8+) specific for SARS-CoV-2 were analyzed. Two hundred subjects were included in the final analysis, with 100 subjects in each priming vaccine group. Most of the AEs were mild, with systemic manifestations occurring between 1 and 7 days following vaccination. A significant difference was observed in the GMT and seropositivity rate following booster dose administration between the two groups. CD8+/CD3+, IFN (interferon)-producing CD8+, and TNF (tumor necrosis factor)-producing CD8+ cells showed significant increases in both groups. The administration of the half-dose mRNA-1273 booster is safe and effective in increasing protection against SARS-CoV-2 infection.

Background: New adult tuberculosis (TB) vaccines are in clinical trials and may be licensed as soon as 2028. However, vaccine rollout requires addressing multiple contextual factors beyond clinical trial findings. This study explored stakeholders’ perspectives on the introduction a new TB vaccine in Indonesia. Methods: We used a mixed-methods approach combining a stakeholder consultation in Jakarta (13/03/2025) among 28 participants with diverse expertise and follow-up interviews with two of those participants. Participants completed a structured questionnaire (via Slido®) consisting of closed- and open-ended questions, adapted into Bahasa. Questions covered factors influencing vaccine introduction, target populations, delivery strategies, regulatory considerations, and lessons from other vaccine programs. Quantitative data were analysed descriptively, and qualitative responses underwent thematic analysis. Results: All participants agreed on the importance of TB vaccine introduction. Key concerns were minimum efficacy of 50% and comparative effectiveness against other interventions, such as TB preventive treatment. Most agreed that vaccine introduction should not depend on local manufacturing capacity, administration route, or dosage. Critical enablers identified were adequate funding, strong political commitment, and demand generation through public acceptance. Priority target populations included people living with HIV/AIDS, individuals with diabetes, household contacts of TB patients, adolescents, and healthcare workers. Major challenges highlighted were vaccine hesitancy, halal issues, misinformation, and limited healthcare worker knowledge. Opinions diverged on feasibility of rollout without IGRA testing. Regulatory and budgeting processes were cited as additional barriers. Conclusions: Introducing new TB vaccines in Indonesia will be complex and concerns extends beyond efficacy. Its success will depend on coordinated strategies to define target populations, design tailored delivery approaches, address vaccine hesitancy, and navigate regulatory and financing challenges.

New adult tuberculosis (TB) vaccines are in clinical trials and may be licensed as soon as 2028. However, vaccine rollout requires addressing multiple contextual factors beyond clinical trial findings. This study explored stakeholders’ perspectives on the introduction of a new TB vaccine in Indonesia. We used a mixed-methods approach combining a stakeholder consultation in Jakarta (13/03/2025) among 28 participants with diverse expertise and follow-up interviews with two of those participants. Participants completed a structured questionnaire (via Slido) consisting of closed- and open-ended questions, adapted into Bahasa. Questions explored factors to be considered regarding vaccine introduction, target populations, delivery strategies, regulatory considerations, and lessons from other vaccine programs. Quantitative data were analysed descriptively, and qualitative responses underwent thematic analysis. All participants agreed on the importance of TB vaccine introduction. Key concerns were minimum efficacy of 50% and comparative effectiveness against other interventions, such as TB preventive treatment. Most agreed that vaccine introduction should not depend on local manufacturing capacity, administration route, or dosage. Critical enablers identified were adequate funding, strong political commitment, and demand generation through public acceptance. Priority target populations included people living with HIV/AIDS, individuals with diabetes, household contacts of TB patients, adolescents, and healthcare workers. Major challenges highlighted were vaccine hesitancy, halal issues, misinformation, and limited healthcare worker knowledge. Opinions diverged regarding the feasibility of vaccine rollout without Interferon-Gamma Release Assay (IGRA) testing: nine opposed vaccinating those with IGRA-negative status, six abstained, and three argued that IGRA-testing was unnecessary and cost-inefficient due to its high price. Regulatory and budgeting processes were cited as additional barriers. Introducing new TB vaccines in Indonesia will be complex and concerns extend beyond efficacy. Its success will depend on coordinated strategies to define target populations, design tailored delivery approaches, address vaccine hesitancy, and navigate regulatory and financing challenges.

Background: Numerous studies have proved the efficacy of vaccination in reducing Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission and the coronavirus disease (COVID-19) burden. However, even though the COVID-19 vaccination coverage is high for primary doses, a booster dose is needed to sustain protection. Continuing our previous research, this study evaluates the immunogenicity and safety of full and half doses of two COVID-19 booster vaccines, ChAdOx1-S (AstraZeneca) and BNT162b2 (Pfizer-BioNTech), in individuals primed with ChAdOx1-S. Methods: This study was an observer-blind randomized controlled trial to evaluate the immunogenicity and safety of half and full doses of two COVID-19 booster vaccine types, BNT162b2 and ChAdOx1-S, among fully vaccinated, ChAdOx1-S-primed individuals in Jakarta, Indonesia. A total of 329 participants were randomized to receive either full or half doses of the booster vaccines, namely the ChAdOx1-S and BNT162b2 COVID-19 vaccines. Immunogenicity was assessed through SARS-CoV-2 antibody titers and neutralizing antibodies (NAbs) at 28 days post-booster, while safety was monitored via adverse event reporting. Results: The results showed that both vaccines demonstrated increased geometric mean titers (GMTs) post-booster. In the ChAdOx1-S booster group, at the baseline visit (day 0) and third visit (day 28), no statistically significant differences in GMT between the half- and full-dose groups were observed (p = 0.970 and 0.539, respectively). In the BNT162b2 group, no statistically significant difference was noted at the baseline visit, while the full dose was higher than the half dose at 28 days (Day 28, p = 0.011). Surrogate virus neutralization tests (sVNTs) and NAbs assays also revealed no significant differences between the half and full dose groups for both the Wuhan strain and the Delta variant. The BNT162b2 group compared to the ChAdOx1-S group revealed a statistically significant increase in IgG levels compared to ChAdOx1-S, with p-values of <0.001 and <0.001 for the half dose and full dose, respectively. This was also reflected in the NAbs test results, where BNT162b2 showed significantly higher levels against both the Wuhan strain and Delta variant. Adverse events were predominantly mild: 79.6% (n = 86/108) in the ChAdOx1-S full-dose group, 75.4% (n = 43/57) in the ChAdOx1-S half-dose group, 84.2% (n = 101/120) in the BNT162b2 full-dose group, and 92.6% (n = 88/95) in the BNT162b2 half-dose group, with pain at the injection site being the most common local reaction and myalgia and headache the most frequent systemic reactions. One serious adverse event was reported, assessed as unrelated to the vaccine. Conclusions: This study confirms that half doses of ChAdOx1-S and BNT162b2 are as immunogenic and safe as full doses, and a heterologous booster is more immunogenic than a homologous booster.