Authors’ reply

We thank Kleebaoon et al.¹ for their comments on our paper. Uptake of a vaccine and more so in the context of a pandemic is influenced by several factors some of which include age, gender, socioeconomic strata, cost, access, perception of risk of the disease and hesitancy among others. It was during the alpha wave of the Covid-19 pandemic that we conducted our first Covid vaccine trial on Covishield™ (September 2020 onwards with the adenovirus vector vaccine/Astrazeneca vaccine where technology was transferred to the Serum Institute of India).² Altruism was the primary motivating factor for participants in this trial study (data on file). The next Covid-19 vaccine study that we did was with COVOVAX™ almost a year later (June 2021) wherein we published the reasons for participation addressed in their letter by Kleebaoon et al. At this time, vaccine availability in India was challenging due to the long waiting period at the public sector and major out-of-pocket expenses for paid vaccines in the private sector. Also, vaccination against Covid-19 had become mandatory by that time for travel and access to public and workplaces. It is no wonder that we identified access to vaccines as the principal reason for participation. Kleebaoon et al. are right in associating vaccine availability (or lack thereof) with the reasons for participation and enrolment in a clinical trial as a means to gain access to vaccines and protect themselves and their families during the pandemic as we saw with the COVOVAX™ study. As regards the country, approximately 68% have received the full vaccination,³ though there would be variation between states and between age groups and the uptake of the booster remains low. Vaccine hesitancy is a spectrum and something countries around the world grapple with⁴ and each country must find its own unique ways to address this challenge.