Effectiveness of COVID-19 mRNA Vaccines in Preventing COVID-19-Associated Outpatient Visits and Hospitalizations Among American Indian and Alaska Native Persons, January–November 2021: A Test-Negative Case-Control Analysis Using Surveillance Data

Abstract

Background Despite the disproportionate morbidity and mortality experienced by American Indian and Alaska Native (AI/AN) persons during the COVID-19 pandemic, few studies have reported vaccine effectiveness (VE) estimates among these communities. Methods We conducted a test-negative case-control analysis among AI/AN persons aged ≥12 years presenting for care from January 1, 2021 through November 30, 2021 to evaluate effectiveness of mRNA COVID-19 vaccines against COVID-19-associated outpatient visits and hospitalizations. Cases and controls were patients with ≥1 symptom consistent with COVID-19-like illness; cases were defined as those test-positive for SARS-CoV-2 and controls were defined as those test-negative for SARS-CoV-2. We used unconditional multivariable logistic regression to estimate VE, defined as 1 minus the adjusted odds ratio for vaccination among cases versus controls. Results The analysis included 207 cases and 267 test-negative controls. Forty-four percent of cases and 78% of controls received two doses of either BNT162b2 or mRNA-1273 vaccine. VE point estimates for two doses of mRNA vaccine were higher for hospitalized participants (94.6% [88.0–97.6]) than outpatient participants (86.5% [63.0–95.0]), but confidence intervals overlapped. Conclusions Among AI/AN persons, mRNA COVID-19 vaccines were highly effective in preventing COVID-associated outpatient visits and hospitalizations. Maintaining high vaccine coverage, including booster doses, will reduce the burden of disease in this population.

Association between COVID-19 Booster Vaccination and COVID-19 Outcomes among U.S. Adults

“…Many studies have already demonstrated the effectiveness of COVID-19 vaccines [13,[40][41][42]. However, this study adds to the current literature by showing that being up to…”

“…Many studies have already demonstrated the effectiveness of COVID-19 vaccines [13,[40][41][42]. However, this study adds to the current literature by showing that being up to date with all eligi-ble COVID-19 vaccinations, especially booster vaccinations, can provide additional protection.…”