The impact of vaccination and outpatient treatment on the economic burden of Covid-19 in the United States omicron era: a systematic literature review.

Aims: To identify and synthesize evidence regarding how coronavirus disease 2019 (COVID-19) interventions, including vaccines and outpatient treatments, have impacted healthcare resource use (HCRU) and costs in the United States (US) during the Omicron era.

Materials And Methods: A systematic literature review (SLR) was performed to identify articles published between 1 January 2021 and 10 March 2023 that assessed the impact of vaccination and outpatient treatment on costs and HCRU outcomes associated with COVID-19. Screening was performed by two independent researchers using predefined inclusion/exclusion criteria.

Results: Fifty-eight unique studies were included in the SLR, of which all reported HCRU outcomes, and one reported costs. Overall, there was a significant reduction in the risk of COVID-19-related hospitalization for patients who received an original monovalent primary series vaccine plus booster dose vs. no vaccination. Moreover, receipt of a booster vaccine was associated with a lower risk of hospitalization vs. primary series vaccination. Evidence also indicated a significantly reduced risk of hospitalizations among recipients of nirmatrelvir/ritonavir (NMV/r), remdesivir, sotrovimab, and molnupiravir compared to non-recipients. Treated and/or vaccinated patients also experienced reductions in intensive care unit (ICU) admissions, length of stay, and emergency department (ED)/urgent care clinic encounters.

Limitations: The identified studies may not represent unique patient populations as many utilized the same regional/national data sources. Synthesis of the evidence was also limited by differences in populations, outcome definitions, and varying duration of follow-up across studies. Additionally, significant gaps, including HCRU associated with long COVID and various high-risk populations and cost data, were observed.

Conclusions: Despite evidence gaps, findings from the SLR highlight the significant positive impact that vaccination and outpatient treatment have had on HCRU in the US, including periods of Omicron predominance. Continued research is needed to inform clinical and policy decision-making in the US as COVID-19 continues to evolve as an endemic disease.