Objective: To investigate the association of using informal sources and reliance on multiple sources of information with actual COVID-19 vaccine uptake, the number of doses of vaccine received, COVID-19 testing, essential preventive measures, and perceived severity of COVID-19. Design: Retrospective cross-sectional study. Setting and Participants: Our study sample consisted of 9584 community-dwelling Medicare beneficiaries, representing a weighted 50,029,030 beneficiaries from the Winter 2021 Medicare Current Beneficiary Survey COVID-19 Supplement. Methods: Two key independent variables were whether a respondent relied on a formal source (ie, traditional news, government guidance, or health care providers) or an informal source (ie, social media, Internet, or friends/family) the most for the COVID-19 information and the total number of information sources a respondent relied on. Results: Compared with beneficiaries relying on formal sources of information, those relying on informal sources of information were less likely to receive COVID-19 vaccine (odds ratio [OR], 0.65; 95% CI, 0.56 -0.75) and COVID-19 testing (OR, 0.85; 95% CI, 0.74-0.98), to engage in preventive behaviors (OR, 0.61; 95% CI, 0.50-0.74), to have high perception of COVID-19 severity, and were more likely to be unvaccinated vs 2 doses of vaccine (relative risk ratio [RRR], 1.64; 95% CI, 1.41-1.91). Relying on more information sources was significantly associated with higher odds of actual vaccine uptake (OR, 1.21; 95% CI, 1.17-1.26), COVID-19 testing (OR, 1.11; 95% CI, 1.07-1.15), engagement of essential preventive behaviors (OR, 1.33; 95% CI, 1.25-1.42), having high perception of COVID-19 severity, and with lower likelihood of being unvaccinated vs 2 doses of vaccine (RRR, 0.82; 0.79-0.85). Conclusions and Implications: The COVID-19 pandemic has made communicating information about coronavirus more important than ever. Our findings suggest that information from formal sources with expertise and more balanced sources of information were key to effective communication to prevent from COVID-19 infection among older adults. & COPY; 2023 The Authors. Published by Elsevier Inc. on behalf of AMDA - The Society for Post-Acute and Long-Term Care Medicine. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).