Durham, NC—Uptake of bivalent COVID-19 booster vaccines has been underwhelming at best, as pharmacists can testify.

That situation exists despite evidence that the boosters increase protection against infection and severe disease. In response, Duke University–led researchers sought to find out why coverage has been so low.

To do that, the study team conducted an online opt-in survey of 1,200 previously vaccinated U.S. residents. The results published in the Morbidity & Mortality Weekly Report revealed that the most common reasons for not getting a bivalent booster dose were lack of awareness about eligibility or availability and overconfidence in immunity. The reasons varied by age group, the authors pointed out.

“All eligible adults should receive a bivalent COVID-19 booster vaccine,” the researchers advised. “To help increase bivalent booster dose coverage, healthcare and public health professionals should use evidence-based strategies to inform persons about booster vaccine recommendations and waning immunity.”

Survey participants were able to select multiple responses from a list of suggested reasons to report why they had or had not received a bivalent booster dose.

The most common reasons cited were:
• Lack of awareness of eligibility for vaccination (23.2%)
• Vaccine availability (19.3%)
• Perceived immunity against infection (18.9%).

After being able to read information about eligibility and availability, 67.8% of participants who had not received the bivalent booster dose indicated that they planned to do so, according to the report. In a follow-up survey 1 month later, 28.6% of these participants reported having received the booster dose and 82.6% responded that they still planned to be boosted.

“Participants who had still not received the booster dose most commonly reported being too busy to get vaccinated (35.6%),” the researchers noted. “To help increase bivalent booster dose coverage, healthcare and public health professionals should use evidence-based strategies to convey information about booster vaccination recommendations and waning immunity, while also working to increase convenient access.”

For the survey, adult participants—all U.S. residents who had received at least one previous COVID-19 vaccine dose—were recruited via Prolific, an online platform. Data collection occurred during November 1 to 5, 2022, (initial survey) and December 6 to 10, 2022 (follow-up survey).

The CDC first recommended a bivalent booster dose for those aged 12 years and older on September 1, 2022. Participants reported if and when they had tested positive for COVID-19 and also when they had received vaccine doses.

Nearly two-thirds (65.4%) of participants were white, and approximately one-half were women. Most participants (95.8%) had received two or more COVID-19 vaccine doses, and among those, 396 (34.4%) had received the bivalent booster dose and 714 (62.1%) had not.

Among those receiving the bivalent booster, the vast majority (90.7%) said they had done so to protect themselves as well as prevent severe disease (80.6%) and protect others (75.0%), with the top reasons consistent among age groups.

Among adults aged up to 39 years, “the most commonly reported reasons for not receiving the bivalent booster dose were being unaware that they were eligible (29.8%), being unaware that updated booster doses were available (23.5%), or believing they still had strong protection against infection (18.4%). The most commonly reported reasons among adults aged 40-59 years were being unaware that they were eligible (22.1%) or believing they still had strong protection against severe disease (21.3%) or infection (18.5%). Among adults aged ≥60 years, the most commonly reported reasons were believing they still had strong protection against infection (20.2%), concern about side effects (17.5%), or being unsure whether the bivalent booster dose was effective (16.1%),” the study advised.

Of those who said they believed they were already sufficiently protected against infection or severe disease, 71.7% had not experienced a SARS-CoV-2 infection or received a COVID-19 vaccine dose within the preceding 6 months, and 114 (51.1%) had never been infected.

“Increased outreach, such as through provider recommendations and trusted messengers, is necessary to increase awareness of eligibility criteria and vaccine availability. Increasing awareness is a crucial first step toward increasing coverage; promotion of tools that provide vaccination guidance (such as CDC’s COVID-19 booster tool) by public health authorities and trusted messengers might help encourage persons who are unsure about bivalent booster dose recommendations to receive the booster dose,” the authors emphasized.

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