Authors’ response

Sir,

We appreciate the insightful feedback from the author of this letter-to-Editor¹ regarding our article titled ‘Immediate adverse events following immunization (AEFI) in drive-through COVID-19 vaccination campaign in Yogyakarta, Indonesia’², published in the March-April 2024 issue of IJMR. This response aims to address the key points raised, particularly concerning the Sinovac vaccine, the scope of our study, and the methodological considerations surrounding drive-through vaccination strategies.

The Sinovac vaccine, an inactivated virus vaccine, presents unique logistical challenges, particularly in non-traditional settings like drive-through clinics. Its storage and stability requirements necessitate careful handling to maintain efficacy³. The inactivated nature of the vaccine has been associated with a lower incidence of adverse reactions compared to mRNA vaccines, which is crucial for public confidence in vaccination campaigns⁴. Furthermore, understanding the specific attributes of the Sinovac vaccine allows for a more nuanced comparison with other vaccines utilised in similar settings, such as mRNA-based vaccines, which have different storage and handling requirements⁵.

We acknowledge the limitations of focusing solely on immediate AEFI, which may not capture the full spectrum of vaccine safety. Longitudinal studies are essential to assess medium to long-term adverse events, as highlighted in various studies that emphasise the importance of comprehensive monitoring post-vaccination^6,7. The National Commission for Adverse Events Following Immunization in Indonesia has confirmed that while some deaths were initially suspected to be related to the Sinovac vaccine, investigations revealed no causal link, underscoring the need for thorough safety evaluation⁸.

The absence of a comparative analysis in our initial critique is a valid concern. Integrating findings from other studies on drive-through vaccination methods will enhance our understanding of whether the challenges faced in Yogyakarta are unique or part of a broader trend. For instance, a study has shown varying levels of acceptance and adverse event profiles between different vaccination strategies, which could inform best practices for drive-through setups⁹. Such comparative analyses are vital for evaluating the effectiveness and safety of drive-through vaccination as a public health strategy.

The selection criteria for participants in the original study warrant further scrutiny. Excluding individuals with comorbid conditions may lead to an incomplete understanding of the vaccine’s safety profile across a diverse population. It is essential to ensure that findings are applicable to a broader audience, particularly as individuals with multiple health issues may respond differently to vaccination. The management of severe adverse effects in drive-through settings is a critical area that requires further exploration. Documenting the protocols in place to handle severe reactions is essential for ensuring patient safety during mass vaccination campaigns¹⁰.

Overall, we are committed to enhancing our discussion to incorporate these insights, ultimately contributing to a more robust understanding of COVID-19 vaccination strategies in various contexts.