Analyzing a Mobile App’s Impacts on COVID-19 Vaccine Trust in Young Black Adults

Analyzing a Mobile App’s Impacts on COVID-19 Vaccine Trust in Young Black Adults

Vaccine hesitancy in the U.S. is multifactorial, influenced by personal beliefs, systemic challenges, and broader socioeconomic barriers. During the COVID-19 pandemic, these issues were further intensified, particularly in Black communities in the South, as many essential workers were young Black adults who were regularly exposed to the virus.

Among Black populations, longstanding mistrust rooted in a history of discrimination and unethical treatment in medical settings continues to influence perceptions of healthcare practices. Misinformation, political polarization, and inconsistent public messaging added layers of confusion and concern. To help address these challenges, a new randomized controlled trial evaluated the impact of an app-based intervention designed to deliver accurate medical information and strengthen vaccine confidence.

Study Overview and Design

The "Tough Talks COVID-19" (TT-C) digital health app was designed specifically for this group, aiming to connect with participants virtually to offer reliable, relatable vaccine information using non-stigmatizing language. Published in July 2025 inScientific Reports, researchers conducted this trial across Alabama, Georgia, and North Carolina, enrolling 360 Black adults between ages 18 and 29 who were unvaccinated or behind on COVID-19 boosters. Half were assigned to use the TT-C app, while the other half received standard vaccine information from the CDC in a flat, textual format.

The TT-C app included videos, peer-led digital storytelling, quizzes, and interactive content designed to engage young adults and address some structural challenges, socioeconomic barriers, and misinformation. The intervention emphasized autonomy supportive behaviors and cultural relevance, avoiding scare tactics or top-down messaging.

Participants were followed for three months, with outcomes measured through self-report surveys and optional vaccine card uploads. Participants in the control group who were insufficiently vaccinated against COVID-19 after the first three months—called the waitlist control group—had the opportunity to engage with the TT-C.

A Look at the Results

By the end of the study, 6.4 percent of all participants had received a new COVID-19 vaccine dose. This included 8.4 percent in the intervention group and 4.7 percent in the control group. While the direction of the effect favored the intervention, the difference was not statistically significant (p=0.174). Similarly, when cohorts were stratified by vaccine status, the intervention effect was greater among those who didn’t complete the primary vaccination series at enrollment.

However, the intervention had a more notable impact on secondary outcomes. Vaccine hesitancy was significantly lower in the TT-C group compared to controls, while vaccine confidence was higher. Researchers determined that the mean scores for vaccine hesitancy was lower and higher for vaccine confidence and knowledge, with statistically significant differences between the intervention and control groups with p-values of p=0.019, p=0.05, and p=0.008, respectively. Vaccine-related conspiracy belief (VCBS) mean scores trended lower in the TT-C group but did not reach significance.

Use and Trust

App engagement played a dose-response effect in outcomes. Participants who completed at least 75 percent of the TT-C content—classified as high use— had 2.19 times higher odds in vaccine uptake compared to controls. While in the low use group 1.53 times higher odds, though neither finding reached statistical significance. Compared to controls, statistically significant (p<0.05) were observed differences in the high use group, with increased vaccine knowledge and confidence, and decreased hesitancy, compared to controls and trend towards significance in VCBS score. In the low use group, the only significant difference observed was an increase in the vaccine confidence score.

Even in the waitlist control group—those who received access to the app after the main study period—similar patterns emerged with 4.8 percent new vaccinations between months three and six. Additionally, vaccine hesitancy dropped significantly, vaccine confidence and knowledge scores increased, while VCBS scores remained. These results reinforce the idea that changing minds is possible through digital engagement, but deeper barriers remain when it comes to changing action.

Study limitations included the inability to update certain components of the TT-C app after launch, despite the need for flexibility in response to the evolving COVID-19 landscape. Participants self-selected into the study, with the majority identifying as female. They were unblinded and reported their own outcomes, introducing potential bias. Additionally, offering a 50-dollar incentive for high app engagement may have contributed to further bias.

The Path Forward

For public health teams seeking scalable, culturally grounded strategies to address vaccine hesitancy, TT-C provides proof that digital tools can move the needle to deliver medically accurate knowledge which improved vaccine confidence. But closing the gap between belief and behavior may require pairing such tools with easier vaccine access, trusted local messengers, or policy-level support.

The intervention’s adaptability—originally modeled on an HIV-focused app—suggests it could be extended to other vaccines or populations facing similar mistrust. In communities historically excluded from clinical decision-making, building trust may be a longer process, but the shift in tone and tools marks an important step forward.