JMIR Publications

ABSTRACT

Background:

Despite strong evidence supporting the efficacy and safety of COVID-19 vaccines, a proportion of the population remains hesitant to receive an immunization. Discrete choice experiments (DCEs) can help assess preferences and decision-making drivers.

Objective:

1) Elicit preferences for COVID-19 vaccines in Canada, Germany, the United Kingdom, and the United States; 2) understand which vaccine attributes people in these countries value; and 3) gain insight into the choices that different population subgroups make regarding COVID-19 vaccines.

Methods:

Participants of the 2019nCoV-408 study were aged ≥18 years; self-reported anti-vaccinationists were excluded. A DCE with a series of two hypothetical vaccine options was embedded into a survey to determine participant treatment preferences (primary objective). Survey questions covered vaccine preference, previous COVID-19 experiences, and demographics; these data were summarized using descriptive statistics to gain an understanding of study participant background. In the DCE, participants were provided choice pairs, one set with and one without an ‘opt-out’ option. Each participant viewed 11 unique vaccine profiles. Vaccine attributes consisted of type (mRNA or protein), level of protection against any or severe COVID-19, risk of side effects (common and serious), and potential coadministration of COVID-19 and influenza vaccines. Selections for attribute level were included for protection and safety (degree of effectiveness and side effect risk, respectively). Participants were stratified by vaccination status (un/partially or fully vaccinated) and disease risk group (high-risk or non–high-risk). A conditional logit model was used to analyze DCE data to estimate participant preferences of vaccine attributes, with the relative importance of each attribute calculated as a percentage to allow for its ranking. Each model was run twice to account for sets with and without the opt-out options.

Results:

The mean age of participants (N=2000) was 48 years, and 51% were male. The DCE revealed that the most important COVID-19 vaccine attributes were protection against severe COVID-19 or any severity of COVID-19 and common side effects. Protection against severe COVID-19 was the most important attribute for fully vaccinated participants, which significantly differed from the un/partially vaccinated subgroup (35% vs 31%; P<.05). Avoiding serious vaccine side effects was a significantly higher priority for the un/partially versus fully vaccinated subgroup (11% vs 8%; P<.05). Attributes with significant differences (P<.05) between the high-risk versus non–high-risk subgroups were protection against severe COVID-19 (38% vs 32%), avoiding common vaccine side effects (12% vs 21%), and avoiding serious vaccine side effects (10% vs 7%).

Conclusions:

This DCE identified COVID-19 vaccine attributes, such as protection against severe COVID-19, that may influence preference and drive choice, and can inform vaccine strategies. The high ranking of common and serious vaccine side effects suggests that, when the efficacy of two vaccines is comparable, safety is a key decision-making factor.