Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
J Clin Epidemiol. 2024 Oct;174:111471. doi: 10.1016/j.jclinepi.2024.111471. Epub 2024 Jul 18.
Registration in the Dutch national COVID-19 vaccination register requires consent from the vaccinee. This causes misclassification of nonconsenting vaccinated persons as being unvaccinated. We quantified and corrected the resulting information bias in vaccine effectiveness (VE) estimates.
National data were used for the period dominated by the SARS-CoV-2 Delta variant (July 11 to November 15, 2021). VE ((1-relative risk)∗100%) against COVID-19 hospitalization and intensive care unit (ICU) admission was estimated for individuals 12 to 49, 50 to 69, and ≥70 years of age using negative binomial regression. Anonymous data on vaccinations administered by the Municipal Health Services were used to determine informed consent percentages and estimate corrected VEs by iteratively imputing corrected vaccination status. Absolute bias was calculated as the absolute change in VE; relative bias as uncorrected/corrected relative risk.
A total of 8804 COVID-19 hospitalizations and 1692 COVID-19 ICU admissions were observed. The bias was largest in the 70+ age group where the nonconsent proportion was 7.0% and observed vaccination coverage was 87%: VE of primary vaccination against hospitalization changed from 75.5% (95% CI 73.5-77.4) before to 85.9% (95% CI 84.7-87.1) after correction (absolute bias -10.4 percentage point, relative bias 1.74). VE against ICU admission in this group was 88.7% (95% CI 86.2-90.8) before and 93.7% (95% CI 92.2-94.9) after correction (absolute bias -5.0 percentage point, relative bias 1.79).
VE estimates can be substantially biased with modest nonconsent percentages for vaccination data registration. Data on covariate-specific nonconsent percentages should be available to correct this bias.
在荷兰国家 COVID-19 疫苗接种登记中，需要疫苗接种者同意。这会导致不同意接种的疫苗接种者被错误地归类为未接种。我们量化并纠正了疫苗效力 (VE) 估计中由此产生的信息偏倚。
使用在 SARS-CoV-2 Delta 变体占主导地位期间（2021 年 7 月 11 日至 11 月 15 日）的全国数据。使用负二项回归估计 12 至 49 岁、50 至 69 岁和≥70 岁个体对 COVID-19 住院和重症监护病房 (ICU) 入院的 VE（（1-相对风险）*100%）。使用市卫生服务部门接种疫苗的匿名数据确定知情同意百分比，并通过迭代推断校正的疫苗接种状态来估计校正后的 VE。绝对偏差计算为 VE 的绝对变化；相对偏差为未校正/校正后的相对风险。
共观察到 8804 例 COVID-19 住院和 1692 例 COVID-19 ICU 入院。年龄在 70 岁以上的人群中偏差最大，其中不同意的比例为 7.0%，观察到的疫苗接种率为 87%：针对住院的初级疫苗接种的 VE 从校正前的 75.5%（95%CI 73.5-77.4）变为校正后的 85.9%（95%CI 84.7-87.1）（绝对偏差-10.4 个百分点，相对偏差 1.74）。该组 ICU 入院的 VE 为 88.7%（95%CI 86.2-90.8），校正后为 93.7%（95%CI 92.2-94.9）（绝对偏差-5.0 个百分点，相对偏差 1.79）。
疫苗接种数据登记中，即使是适度的不同意百分比，也会对 VE 估计产生重大偏差。应该提供关于协变量特定不同意百分比的数据，以纠正这种偏差。
