Acceptability of a COVID-19 Vaccine among Adults in the United States: How Many People Would Get Vaccinated?

"...findings can help guide future efforts to increase COVID-19 vaccine acceptability (and uptake if a vaccine becomes available)."

Vaccination could be a key protective behaviour for managing the COVID-19 pandemic. At the time of this writing, several prophylactic vaccines against COVID-19 are in development across multiple countries. The present study examined acceptability of a COVID-19 vaccine among a national sample of adults in the United States (US). Such information could be useful to public health leaders and policymakers as they shape efforts to communicate the benefits (and any risks) of a COVID-19 vaccine.

The researchers conducted a cross-sectional online survey of adults aged 18 and older (n=2,006) in the US in May 2020, about 2 months after COVID-19 was declared a pandemic. Multivariable relative risk regression identified correlates of participants' willingness to get a COVID-19 vaccine (i.e., vaccine acceptability).

Overall, 69% of participants were classified as willing to get a COVID-19 vaccine (48% were definitely willing, and 21% were probably willing), and 31% were classified as not willing (17% were not sure, 5% were probably not willing, and 9% were definitely not willing).

Participants were less likely to be willing to get vaccinated if reported a higher level of perceived potential vaccine harms (relative risk (RR) = 0.95, 95% confidence interval (CI): 0.92-0.98), were female (RR = 0.91, 95% CI: 0.87-0.96), or were non-Latinx black (RR = 0.81, 95% CI: 0.74-0.90). The latter finding/pattern concerns the researchers, as data suggest that non-Latinx blacks have among the highest COVID-19 incidence and mortality rates in the US. Furthermore, only 35% of participants in the study would pay US$50 or more out-of-pocket for a COVID-19 vaccine, which indicates the need to facilitate vaccine uptake by reducing potential financial barriers.

Participants were more likely to be willing to get vaccinated:

• ...if they thought their healthcare provider would recommend vaccination (RR = 1.73, 95% CI: 1.49-2.02);
• ...if they were moderate (RR = 1.09, 95% CI: 1.02-1.16) or liberal (RR = 1.14, 95% CI: 1.07-1.22) in their political leaning (likely reflective of the polarisation of issues related to COVID-19 in the US); and/or
• ...if they reported higher levels of perceived likelihood getting a COVID-19 infection in the future (RR = 1.05, 95% CI: 1.01-1.09), perceived severity of COVID-19 infection (RR = 1.08, 95% CI: 1.04-1.11), or perceived effectiveness of a COVID-19 vaccine (RR = 1.46, 95% CI: 1.40-1.52). These beliefs are central constructs of multiple health behaviour theories (e.g., Health Belief Model, Protection Motivation Theory) and may represent modifiable targets for future interventions.

The study also explores factors in vaccination decisions. For example, participants who were willing to get a COVID-19 vaccine were more likely to indicate the following factors as mattering in their vaccination decisions compared to those who were not willing (all p < 0.05): how well the vaccine works (84% vs. 74%), if a doctor recommends the vaccine (82% vs. 54%), their health history (75% vs. 66%), the number of people getting infected with COVID-19 (74% vs. 66%), their age (63% vs. 54%), and recent or upcoming travel outside of the US (64% vs. 52%). Conversely, participants who were willing to get vaccinated were less likely to indicate potential vaccine side effects as mattering in their vaccination decisions (53% vs. 69%, p < 0.05). Overall, few participants indicated that the opinions of their family members and friends (38%) and their race/ethnicity (21%) would matter in their vaccination decisions.

Per the researchers, the findings about factors that may differ depending on how ready a person is to get vaccinated can inform future communication efforts about a COVID-19 vaccine. For example, communications for people classified as willing to get vaccinated in the study may need to focus more on issues like vaccine efficacy and healthcare provider recommendation, whereas communications for people who are less ready to get vaccinated may need to focus more on reducing concern about vaccine side effects. This approach would coincide with several stage theories in health behaviour (e.g., Transtheoretical Model and Precaution Adoption Process Model), in which the resources and information needed often vary depending on a person's stage of behaviour change.

In short, the results "highlight that vaccine acceptability may differ by several demographic characteristics, as well as the key role that healthcare providers and modifiable health beliefs play in acceptability of a COVID-19 vaccine." In conclusion: "Moving forward, it will be important to monitor temporal changes in acceptability as vaccine development continues, and, if a vaccine becomes available, determine how estimates of acceptability translate into vaccine uptake since willingness/intent may not always lead to actual behavior."