Observations of COVID-19 vaccine coverage and vaccine hesitancy on COVID-19 outbreak: An American ecological study

In this ecological study, we aim to establish the role vaccines play in bringing the pandemic under control, as well as the impact of pathogen variants, vaccine hesitancy, and medical resource availability during the process by utilizing publicly available data. The study spans a three-year data collection period for daily hospital admissions due to COVID-19 and the daily reported cases of COVID-19 across all 50 states in the USA. In doing so, we aim to demonstrate the difference in severity of the SARS-CoV-2 pathogen among vaccinated and unvaccinated populations in the USA. The study assesses the correlation of COVID-19 vaccines (e.g., Pfizer, Moderna, and Janssen) and disease outcomes (transmissibility, severity, and deaths) caused by different strains of SARSCoV-2 and establishes a negative correlation between COVID-19 vaccine and disease outcomes. By considering potential confounders in vaccine hesitancy, medical resource availability and vaccine dosage, we demonstrate the aforementioned to be insubstantial in predicting disease outcomes while the latter displays a contrasting significance in terms of disease outcomes. Between all the major variants of concern, the Delta and Omicron variants in particular have been associated with higher virulence and transmissibility factors respectively. Hence, the CDC continues to encourage the US population to get vaccinated since vaccines are one of the most effective ways to protect the community from potential outbreaks and prevent severe disease manifestations.