Scientists developed efficacious vaccines against COVID-19 in record time. The next big challenge awaits: convincing enough people to get vaccinated to achieve herd immunity.
In late November 2020, we launched a polling effort through askNivi, our free conversational agent for health, to monitor public opinion about COVID-19 vaccines. We’re running advertisements on social media that invite people to share their opinion via an askNivi poll (Messenger or WhatsApp). The people who respond are a self-selected convenience sample of mobile internet users, so we use multilevel Bayesian regression and post-stratification to make the results more representative of the population.
After asking users to select a language, accept our terms and conditions, and provide basic demographic information, we ask the following1:
- How concerned are you about COVID-19 🦠?
- Have you or anyone you live with 🏠 ever had COVID-19?
- If a vaccine 💉 that protected you from the coronavirus was available for free to everyone who wanted it today, would you get it?
Over two rounds of data collection (Nov 23-29; Dec 9-16), 722 people in India completed the survey with complete demographic information for adjustment. 78 percent of respondents said they would definitely (61%) or probably (17%) get vaccinated, similar to what recent polls found in India (74%) (Lazarus et al. 2020). This did not vary much across subgroups or shift much across rounds. We estimate that the probability is greater than 95% that at least 60% of people would be likely to get vaccinated if the vaccine were available for free today.
This is likely to be sufficient public support to reach herd immunity in India with an efficacious vaccine and a low reproduction number. According to Anderson et al. (2020), herd immunity could be achieved with 39% coverage with a vaccine that has 70% efficacy given an R0 value of 1.4 (estimated in India by Marimuthu et al. 2021).
Unsurprisingly, the people who are not concerned about COVID-19 are more likely to say they will not get vaccinated. The same goes for people who never or rarely wear masks in public.
The most common reasons for not wanting to get vaccinated were believing that the vaccine is unnecessary and general distrust in vaccines. Among people who said they were likely to get vaccinated, roughly two-fifths said their likelihood of getting vaccinated would decrease somewhat if the vaccine requires multiple doses. Half said they would be less likely to act if minor side effects are reported.
See below for additional details from our initial polling in India. A potential limitation of the data is that the respondents are all mobile internet users, and are thus likely to be wealthier and more educated on average. A recent global analysis suggested that fewer years of education was linked to less uptake of vaccines (Figueiredo et al. 2020). If our sample is more educated relative to the general population, then our estimates could be biased toward vaccine uptake. We adjusted for age, county, gender, setting (rural/urban), and language.
Anderson, Roy M, Carolin Vegvari, James Truscott, and Benjamin S Collyer. 2020. “Challenges in Creating Herd Immunity to Sars-Cov-2 Infection by Mass Vaccination.” The Lancet 396 (10263): 1614–6.
Figueiredo, Alexandre de, Clarissa Simas, Emilie Karafillakis, Pauline Paterson, and Heidi J Larson. 2020. “Mapping Global Trends in Vaccine Confidence and Investigating Barriers to Vaccine Uptake: A Large-Scale Retrospective Temporal Modelling Study.” The Lancet 396 (10255): 898–908.
Lazarus, Jeffrey V, Scott C Ratzan, Adam Palayew, Lawrence O Gostin, Heidi J Larson, Kenneth Rabin, Spencer Kimball, and Ayman El-Mohandes. 2020. “A Global Survey of Potential Acceptance of a Covid-19 Vaccine.” Nature Medicine, 1–4.
Marimuthu, S, Melvin Joy, B Malavika, Ambily Nadaraj, Edwin Sam Asirvatham, and L Jeyaseelan. 2021. “Modelling of Reproduction Number for Covid-19 in India and High Incidence States.” Clinical Epidemiology and Global Health 9: 57–61.
If people are willing to continue answering questions, the extended poll asks about children, mask wearing, information sources, and reasons for not wanting to get vaccinated.
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