Ithaca, NY—Pharmacists are still waiting in the wings for their starring role in delivering COVID-19 vaccines to Americans, but it remains unclear how great the demand will be.
A recent survey of adults in the U.S. determined that vaccine-related attributes and political characteristics were associated with preferences for opting for a hypothetical COVID-19 vaccine. Both vaccine-related attributes, such as efficacy, adverse effects, and protection duration played a role, as did political factors, such as the FDA approval process, national origin of vaccine, and endorsements.
Cornell University–led researchers say they hope the results will help improve public-health campaigns to address vaccine hesitancy when a COVID-19 vaccine becomes available.
The report in JAMA Network Open points out that, while the development of a coronavirus disease 2019 (COVID-19) vaccine has progressed at historic speed, stemming the pandemic also requires widespread public uptake of the vaccine.
The study team sought to examine the factors associated with survey participants’ self-reported likelihood of selecting and receiving a hypothetical COVID-19 vaccine.
To do that, researchers conducted a survey study of a nonprobability convenience sample of 2,000 recruited participants to estimate respondents’ probability of choosing a vaccine and willingness to receive vaccination.
The willingness to receive each hypothetical vaccine individually was measured, with the survey presenting respondents with five choice tasks. In each, participants evaluated two hypothetical COVID-19 vaccines and were asked whether they would choose vaccine A, vaccine B, or neither vaccine.
For the survey on July 9, 2020, vaccine attributes included efficacy, protection duration, major adverse effects, minor adverse effects, FDA approval process, national origin of vaccine, and endorsement. Researchers randomly assigned levels of each attribute for each vaccine and attribute order was randomized across participants.
Participating were 1,971 U.S. adults with a median age of 43 years [interquartile range, 30-58 years]; 999 (51%) were women, 1,432 (73%) were white, 277 (14%) were Black, and 190 (10%) were Latinx.
Results indicate than an increase in efficacy from 50% to 70% was associated with a higher probability of choosing a vaccine (coefficient, 0.07; 95% CI, 0.06-0.09), and an increase from 50% to 90% was associated with a higher probability of choosing a vaccine (coefficient, 0.16; 95% CI, 0.15-0.18).
In addition, the survey determined that an increase in protection duration from 1 year to 5 years was associated with a higher probability of choosing a vaccine (coefficient, 0.05 95% CI, 0.04-0.07). At the same time, a decrease in the incidence of major adverse effects from 1 in 10,000 to 1 in 1,000,000 was associated with a higher probability of choosing a vaccine (coefficient, 0.07; 95% CI, 0.05-0.08).
Other findings include:
• An FDA emergency-use authorization was associated with a lower probability of choosing a vaccine (coefficient, −0.03; 95% CI, −0.04 to −0.01) compared with full FDA approval.
• A vaccine that originated from a non-U.S. country was associated with a lower probability of choosing a vaccine (China: −0.13 [95% CI, −0.15 to −0.11]; UK: −0.04 [95% CI, −0.06 to −0.02]).
• Endorsements from the CDC (coefficient, 0.09; 95% CI, 0.07-0.11) and the World Health Organization (coefficient, 0.06; 95% CI, 0.04-0.08), compared with an endorsement from President Donald Trump were associated with higher probabilities of choosing a vaccine.
Researchers note that analyses of participants’ willingness to receive each vaccine when assessed individually yielded similar results: An increase in efficacy from 50% to 90% was associated with a 10% higher marginal mean willingness to receive a vaccine (from 0.51 to 0.61), while a reduction in the incidence of major side effects was associated with a 4% higher marginal mean willingness to receive a vaccine (from 0.54 to 0.58). In addition, according to the study, a vaccine originating in China was associated with a 10% lower willingness to receive a vaccine versus one developed in the United States (from 0.60 to 0.50).
Endorsements from the CDC and WHO were associated with increases in willingness to receive a vaccine (7% and 6%, respectively) from a baseline endorsement by President Trump (from 0.52 to 0.59 and from 0.52 to 0.58, respectively).
The authors warn, “A growing anti-vaccination movement threatens such efforts in the United States, Europe and Asia. Existing surveys suggest that U.S. public support for a hypothetical COVID-19 vaccination may not reach the thresholds necessary to achieve herd immunity, which is estimated at 70% for COVID-19.”
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