Factors Associated with Delayed or Missed Second-Dose mRNA COVID-19 Vaccination among Persons >12 Years of Age, United States

Abstract

I n December 2020, the US Food and Drug Administration (FDA) issued Emergency Use Authorizations (EUAs) for the Pfizer BioNTech (https://www. pfizer.com) and Moderna (https://www.modernatx. com) 2-dose primary mRNA COVID-19 vaccine series (1,2). The Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices, part of the National Center for Immunization and Respiratory Diseases, prioritized certain populations to be offered the COVID-19 vaccination first, including healthcare personnel, long-term care facility residents, persons >65 years of age, persons 16-64 years of age with high-risk medical conditions, and essential workers (3). Starting in March 2021, Pfizer-BioNTech and Moderna COVID-19 vaccines have been available at pharmacies and from other medical practice providers for anyone >16 years of age. In the 1-year period of this analysis, the recommended intervals between the 2 primary doses were 21 days for the Pfizer-BioNTech vaccine and 28 days for the Moderna vaccine (4). On May 10, 2021, FDA expanded the EUA for the Pfizer COVID-19 vaccine to include persons 12-15 years of age (5). During August-November 2021, FDA approved a series of EUAs: 1 for an additional primary dose for immunocompromised persons and 1 for a booster dose for persons >18 years of age (6).In the summer of 2021, one of every 10 US persons received the first dose of an mRNA COVID-19 vaccine, ≈15 million still had not received the second dose, and many more had received the second dose outside the recommended intervals between doses (7). Persons who start the primary series are presumably amenable to initial vaccination but may then either delay completing or may fail to complete the series. Delayed or missed recommended COVID-19 vaccine doses can hamper national efforts to reduce COVID-19-associated illness, hospitalization, and death (8-10). More information about this population is valuable for addressing second-dose vaccination

Mapping of Public Approach towards COVID-19 Vaccine for Preparedness and Resilience of Emerging Threats to Facilitate Cross-Country Systematic Roll-Out of Resources

“…Earlier studies support our findings where when compared with first-dose, recipients were more likely to have uncertainty about the next dose [39]. Our research findings are also consistent with the Government of India's Economic Survey, 2023.…”

Mapping of Public Approach towards COVID-19 Vaccine for Preparedness and Resilience of Emerging Threats to Facilitate Cross-Country Systematic Roll-Out of Resources

“…This finding is consistent with the reports from other studies where when compared with firstdose recipients were more likely to have delayed or missed the second dose (64). Our research findings are also consistent with the Government of India's Economic Survey, 2023.…”

Modeling Behavior and Vaccine Hesitancy Using Twitter-Derived US Population Sentiment during the COVID-19 Pandemic to Predict Daily Vaccination Inoculations

“…If a second-dose inoculation is viewed as another voluntary acceptance challenge, then the Rogers estimation of 84% of the first-dose recipients would yield that an estimate of 70.6% of the total population will receive a second-dose inoculation. As of 7 February 2023 and remarkably consistent with the Rogers estimate of 70.6% acceptance, the CDC reports that 73.2% of the US population 5 years of age or greater are inoculated with one dose [ 38 ]. The respective 1.5% and 2.6% higher observed inoculation rates over that estimated by the Rogers Curve may be due to vaccination mandates imposed by government and/or employers.…”

“…This assumption infers that approximately 84% of the population might voluntarily accept a first-dose inoculation within the timeframe of the pandemic. As of 7 February 2023, and remarkably consistent with the Rogers estimate of 84% acceptance, the CDC reports that 85.5% of the US population 5 years of age or greater are inoculated with one dose [ 38 ]. If a second-dose inoculation is viewed as another voluntary acceptance challenge, then the Rogers estimation of 84% of the first-dose recipients would yield that an estimate of 70.6% of the total population will receive a second-dose inoculation.…”

“…Ref. [ 38 ] studied the second-dose phenomenon and in part found that behavior differed by population segments driven largely by age. Specifically, “Compared with first-dose recipients 18–39 years of age, recipients 40–64 and >65 years of age were less likely to have missed a second dose.…”