ABSTRACT
The launch of the COVID-19 vaccination program was the largest vaccination campaign in U.S. history, with an unprecedented demand for vaccine and new vaccination providers, warranting significant education and communication efforts. NIP-INFO (nipinfo@cdc.gov) is the Centers for Disease Control and Prevention's (CDC's) immunization inquiry response service, and it receives inquiries for COVID-19 and routine non-COVID vaccines. A qualitative analysis of NIP-INFO's content was performed to better characterize and understand some of the knowledge gaps and reasons that COVID-19 vaccine administration errors occur. A total of 734 COVID-19 vaccine administration error inquiries were received between January 2021 and April 2022. The most frequent inquiries related to storage (n = 191; 26.0%), incorrect dosage or product (n = 190; 25.9%), unauthorized age group (n = 108; 14.7%), and schedule (n = 105; 14.3%). Training and communication strategies are imperative to ensure proper vaccine administration and build and maintain vaccine confidence.
ABSTRACT
Background: We estimated SARS-CoV-2 Delta- and Omicron-specific effectiveness of two and three mRNA COVID-19 vaccine doses in adults against symptomatic illness in US outpatient settings. Methods: Between October 1, 2021, and February 12, 2022, research staff consented and enrolled eligible participants who had fever, cough, or loss of taste or smell and sought outpatient medical care or clinical SARS-CoV-2 testing within 10 days of illness onset. Using the test-negative design, we compared the odds of receiving two or three mRNA COVID-19 vaccine doses among SARS-CoV-2 cases versus controls using logistic regression. Regression models were adjusted for study site, age, onset week, and prior SARS-CoV-2 infection. Vaccine effectiveness (VE) was calculated as (1 - adjusted odds ratio) × 100%. Results: Among 3847 participants included for analysis, 574 (32%) of 1775 tested positive for SARS-CoV-2 during the Delta predominant period and 1006 (56%) of 1794 participants tested positive during the Omicron predominant period. When Delta predominated, VE against symptomatic illness in outpatient settings was 63% (95% CI: 51% to 72%) among mRNA two-dose recipients and 96% (95% CI: 93% to 98%) for three-dose recipients. When Omicron predominated, VE was 21% (95% CI: -6% to 41%) among two-dose recipients and 62% (95% CI: 48% to 72%) among three-dose recipients. Conclusions: In this adult population, three mRNA COVID-19 vaccine doses provided substantial protection against symptomatic illness in outpatient settings when the Omicron variant became the predominant cause of COVID-19 in the United States. These findings support the recommendation for a third mRNA COVID-19 vaccine dose.