OBJECTIVE: This study examined potential risk factors for not completing a 2-dose primary series of mRNA COVID-19 vaccination.
METHODS: We conducted a retrospective cohort study among members aged ≥18 years from a large integrated health care system, Kaiser Permanente Southern California, from December 14, 2020, to June 30, 2022. Noncompletion of the 2-dose primary series was defined as not completing the second dose within 6 months after receipt of the first dose. Crude noncompletion rates were estimated overall and by demographic characteristics, health care use patterns, comorbidity, and community-level socioeconomic factors. A Poisson regression model was fit to examine associations of individual-level and community-level risk factors with noncompletion of the 2-dose primary series.
RESULTS: Among 2.5 million recipients of ≥1 dose of mRNA COVID-19 vaccines, 3.3% (n=81,202) did not complete the second dose within 6 months. Members aged 25-44 years, 65-74 years, and ≥75 years were less likely to not complete the 2-dose primary series than those aged 18-24 years, while members aged 45-64 years were more likely to not complete the 2-dose primary series (adjusted risk ratio [aRR] 1.13, 95% CI 1.10-1.15). Male sex was associated with a higher risk of noncompletion (aRR 1.17, 95% CI 1.15-1.19). Hispanic and non-Hispanic Black race/ethnicity were associated with a lower risk of noncompletion (range aRR 0.78-0.91). Having Medicaid and prior influenza vaccination were associated with a higher risk of noncompletion. Having SARS-CoV-2 infection, experiencing an adverse event, or having an inpatient and emergency department visit during the minimum recommended dose intervals were associated with a higher risk of not completing the 2-dose primary series (aRR 1.98, 95% CI 1.85-2.12; 1.99, 95% CI 1.43-2.76; and 1.85, 95% CI 1.77-1.93, respectively). Those who received the first dose after June 30, 2021, were more likely to not complete the 2-dose primary series within 6 months of receipt of the first dose.
CONCLUSIONS: Despite limitations such as being a single-site study and the inability to consider social factors such as employment and vaccine attitudes, our study identified several risk factors for not completing a 2-dose primary series of mRNA vaccination, including being male; having Medicaid coverage; and experiencing SARS-CoV-2 infection, adverse events, or inpatient and emergency department visits during the minimum recommended dose intervals. These findings can inform future efforts in developing effective strategies to enhance vaccination coverage and improve the completion rate of necessary doses.
目的:本研究调查了未完成2剂量主要系列COVID-19mRNA疫苗接种的潜在危险因素。
方法:我们对来自大型综合医疗保健系统的18岁以上成员进行了一项回顾性队列研究,KaiserPermanente南加州,从2020年12月14日至2022年6月30日。2-剂量主要系列的未完成定义为在接受第一剂量后6个月内未完成第二剂量。粗略的未完成率是根据总体和人口特征进行估计的,医疗保健使用模式,合并症,和社区层面的社会经济因素。Poisson回归模型适合于检查个体水平和社区水平的危险因素与未完成2剂量主要系列的关联。
结果:在250万接受1剂以上mRNACOVID-19疫苗的接受者中,3.3%(n=81,202)在6个月内没有完成第二次给药。25-44岁的成员,65-74岁,与年龄在18-24岁的人相比,≥75岁的人不太可能完成2剂量主要系列,而年龄在45-64岁的成员更有可能未完成2剂主要系列(校正风险比[aRR]1.13,95%CI1.10-1.15).男性与较高的未完成风险相关(RR1.17,95%CI1.15-1.19)。西班牙裔和非西班牙裔黑人种族/种族与较低的未完成风险相关(范围为0.78-0.91)。有医疗补助和先前的流感疫苗接种与更高的未完成风险相关。有SARS-CoV-2感染,经历不良事件,或在最低推荐剂量间隔期间进行住院和急诊科就诊与未完成2剂主要系列的风险较高相关(分别为aRR1.98,95%CI1.85-2.12;1.99,95%CI1.43-2.76;和1.85,95%CI1.77-1.93).那些在2021年6月30日之后接受第一剂的人更有可能在接受第一剂的6个月内没有完成2剂主要系列。
结论:尽管存在单中心研究和无法考虑就业和疫苗态度等社会因素等局限性,我们的研究确定了一些没有完成2剂量的mRNA疫苗接种的风险因素,包括男性;有医疗补助保险;经历SARS-CoV-2感染,不良事件,或在最小推荐剂量间隔期间住院和急诊科就诊。这些发现可以为今后制定有效策略以提高疫苗接种覆盖率和提高必要剂量完成率提供信息。