Reluctance to take Covid-19 vaccines could hinder achieving herd immunity sooner

As the nation begins its recovery from the COVID-19 pandemic through a massive vaccine rollout, the entire focus is on identifying the priority groups, the logistics of vaccine distribution, and whether the vaccine is a private or public good. The fact that people’s willingness to take vaccines might play a major role in ensuring that herd immunity is achieved for life to get back to normal is not fully acknowledged.

The Delhi-NCR Coronavirus Telephone Survey-round 4 (DCVTS-4), administered between December 23, 2020, and January 4, 2021, provides some evidence of vaccine hesitancy. The DCVTS-4, conducted by the NCAER National Data Innovation Centre, resurveyed randomly selected households contacted in the earlier rounds of DCVTS from Delhi-NCR — this includes Delhi as well as rural and urban areas from selected districts of Haryana, Rajasthan and Uttar Pradesh.

DCVTS-4 asked its respondents, “In a few months if vaccines were to be available to prevent COVID, will you be willing to take it?” The findings show that about 20 per cent respondents are certain about not taking the vaccine, with significant rural (22.4 per cent) and urban (17.5 per cent) differences being observed. An additional 4 per cent mentioned that they will not take it as they were already infected. Another 15 per cent are unsure about taking the vaccine. Combining all these three categories, one can argue that at this point, vaccine hesitancy is quite high (39 per cent).

No significant association was observed between age, gender of respondent and vaccine hesitancy. The less educated (0-4 years of education) are more hesitant to take the vaccines (52 per cent). Even after adjusting for education, Muslims and Scheduled Caste respondents are significantly more likely to register hesitancy in getting vaccinated. Hesitancy among minority groups is also seen in other countries. A recent PEW poll in the US found that while 61 per cent of White respondents would definitely or probably get vaccinated, only 42 per cent of Black respondents would. Improved trust in vaccine development and approval process, as well as the overall trust in government health systems, may play an important role in reducing vaccine hesitancy.

The development, testing and approval of COVID-19 vaccines have been achieved within record time. On the one hand, this is an unprecedented achievement, but on the other, it might lead to vaccine hesitancy due to concerns regarding compliance, protocols and approval process.

Evidence of vaccine efficacy is the key in any vaccine approval process. Efficacy is defined as the percentage reduction in disease between participants who were vaccinated and those who received placebo in a randomised controlled trial set-up.

Efficacy data of the sister vaccines of Covishield came from four ongoing blinded, randomised, controlled trials done across the UK, Brazil, and South Africa which were published in the general medical journal The Lancet on December 8. Between April 23 and November 4, 2020, roughly 24,000 participants were enrolled for an evaluation of the safety, immunogenicity and efficacy of this vaccine and data from more than 11,000 participants was included in the interim efficacy analysis. The overall efficacy of the vaccine was found to be around 70 per cent, which is above the WHO recommended threshold of 50 per cent. Approval of Covishield in India is based on these results as well as safety and immunogenicity data from the Covishield phase 2 clinical trial in India led by SII.

For Covaxin, Bharat Biotech undertook a large phase 3 clinical trial involving roughly 26,000 participants across 26 sites in India to assess its safety, immunogenicity, and efficacy. However, no efficacy data from this trial was available for approving the vaccine as the phase 3 trial started only in mid-November. A phase 2 trial of Covaxin involving 380 participants found tolerable safety outcomes and enhanced immune responses. However, the results from the phase 2 trial do not permit efficacy assessments.

The effect of any vaccine on the course of the COVID-19 pandemic is complex and there are many potential scenarios after mass vaccination starts. Clinical trials, particularly those conducted within an expedited timeframe, do not allow us to fully evaluate the ability of a vaccine to protect against severe disease and prevent death. Moreover, side-effects in specific populations may only emerge once mass vaccination starts with a larger sample size under real-life conditions for all individuals, without any exclusion criteria. Hence, it is crucial that the Serum Institute and Bharat Biotech, in collaboration with other research organisations, continue doing post-marketing surveillance studies of vaccine effectiveness and monitor the side effects over a longer period.

Vaccine hesitancy cannot be addressed by pharmaceutical companies alone: Governments and health policymakers need to play a proactive role in promoting vaccination by educating the public and implementing policies that take care of health and financial risks associated with adverse events following vaccination. Health providers will need to be trained in responding to questions and identifying and treating potential side-effects. People will need to understand where and when to go for vaccination, the doses and schedules, what side-effects to expect and how to handle them, and how to receive medical care for treatment of adverse events, if any. Special outreach efforts may be needed for low-literacy populations and those who do not find it easy to trust medical systems.

The beginning of the vaccination programme suggests that the end is in sight. How quickly we reach the goal post depends on how well prepared we are as we enter the race.

This article first appeared in the print edition on January 28, 2021 under the title ‘Between vaccine and victory’. Pramanik is senior fellow and deputy director NCAER National Data Innovation Centre, Desai is professor and director, NCAER NDIC. Views are personal.

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