PROmotion of COVID-19 BOOSTer VA(X)Ccination in the Emergency Department - PROBOOSTVAXED

I. Overview On January 22, 2020, Acting Health and Human Services Secretary Norris Cochran declared COVID-19 a national public health emergency, an action that eventually enabled emergency authorization for free COVID-19 vaccines, testing and treatments. This public health declaration has been renewed seven times for 90-day intervals, as required under section 319 of the Public Health Service (PHS) Act. Under this declaration over the past two years, the US government has provided full support and distribution of COVID-19 vaccines and therapeutics (antibody therapies, remdesivir, and nirmatrelvir/ritonavir), such that they have been widely available and free of charge to all Americans. Although these measures have not, by any means, ended the pandemic, it is clear from multiple epidemiologic modeling studies that they have decreased hospitalizations and saved hundreds of thousands of lives. They have also led to a narrowing of the profound morbidity and mortality disparities gap that was seen in minority populations in the first two waves of the pandemic.

The PROCOVAXED trial was a multicenter study that sought to decrease COVID-19 vaccine hesitancy and increase COVID-19 vaccine uptake through the use of vaccine messaging platforms in the emergency department (ED). In this trial, investigators found that implementation of our COVID-19 messaging platforms (videos, information sheets and scripted, direct messaging) were associated with greater COVID-19 vaccine acceptance and uptake among unvaccinated ED patients (Rodriguez RM, Nichol G, Eucker SA, et al. Effect of COVID-19 Vaccine Messaging Platforms in Emergency Departments on Vaccine Acceptance and Uptake: A Cluster Randomized Clinical Trial. JAMA Intern Med. 2023;183(2):115-123. doi:10.1001/jamainternmed.2022.5909).

In January 2022, the investigators extended PROCOVAXED by shifting the focus to vaccinated ED patients to examine the timely and critically important topic of booster vaccine hesitancy in underserved ED populations. To better characterize COVID-19 booster hesitancy, the investigators performed a cross-sectional study at five high-volume, safety-net hospital EDs in four cities (San Francisco, Philadelphia, Seattle, and Durham, NC) using survey tools to gather quantitative data on vaccination status, demographic variables, usual source of care, and attitudes toward booster vaccination. Of 771 participants who had completed their full initial series, 316 (41%) had not received any booster vaccine. Among these 316 non-boosted participants, 179 (57%, 95% CI 51-62) stated they would decline or were unsure whether they would accept a booster vaccine if it was offered to them (i.e., booster-hesitant). Investigators found the following associations with booster vaccine hesitancy: age 35-49 years vs age 18-34 years (OR 1.16, 95% CI 0.99-1.36); Asian vs White race (OR 0.21, 95% CI 0.05-0.93); Hispanic/Latino vs White ethnicity (OR 1.59, 95% CI 0.82-3.09); primary language non-English vs English (OR 2.35, 95% CI 1.49-3.71); and Republican vs Democrat party affiliation (OR 6.07, 95% CI 4.21-8.75). The three most common reasons for booster vaccine hesitancy were a preference to wait for more information (25%), concerns about side effects and safety (24%), and "I don't need one because I'm fully vaccinated" (20%).

Recognizing the ED as a unique opportunity to address COVID-19 booster vaccine hesitancy in underserved populations, the investigators will launch the PROmotion of COVID-19 BOOSTer VA(X)ccination in the Emergency Department (PROBOOSTVAXED) trial as an extension of the PROCOVAXED trial, seeking to increase COVID-19 booster vaccine acceptance and uptake among vaccinated ED patients. Because of Omicron variant-associated surges during the COVID-19 pandemic with corresponding research staff illness and ED overcrowding, the investigators found wide week-to-week fluctuations in enrollment in the PROCOVAXED study. To reduce this variability of enrollment, the investigators have changed the unit of randomization from 1-week to 1-day in the PROBOOSTVAXED trial.

As of May 11, 2023, the COVID-19 public health emergency ended. Consequently, not only are the costs for vaccines, testing, and treatments shifted to health insurers and patients via commercial payment mechanisms, but COVID-19 vaccines are no longer available in some EDs. Since our research focuses on the delivery and availability of vaccines to underserved populations whose only health care access occurs in EDs, the team believes that this represents a potential barrier to 30-day vaccine uptake in these populations. The investigators have been informed that only some of the PROBOOSTVAXED study sites will have COVID-19 vaccines available for distribution in the ED, and this availability is subject to change throughout the study period. Nevertheless, the team will proceed with the same research protocol, however, the investigators feel it is important to examine how ED vaccine availability will affect 30-day vaccine uptake in underserved populations. They will therefore be performing additional subgroup analyses that compare 30-day vaccine uptake among sites with available COVID-19 vaccine to those without for the intervention and control arms.They will also evaluate whether patient costs of vaccines are a deterrent to acceptance and uptake.