Trends colliding: aging comprehensive family physicians and the growing complexity of their patients
Premji K, Glazier RH, Green ME, Khan S, Schultz S, Mathews M, Nastos S, Frymire E, Ryan BL. Can Fam Physician. 2025 Jun 16.
Limited data exists on the effectiveness of a third COVID-19 vaccine dose in solid organ transplant recipients. We conducted a population-based cohort study using linked healthcare databases from Ontario, Canada to answer this question. We included solid organ transplant recipients (n=12,842) as of December 14, 2020, with follow-up until November 28, 2021. We used an extended Cox proportional hazards model with vaccination status, including BNT162b2, mRNA-1273 and ChAdOx1 vaccines, modelled as a time-dependent exposure. Individuals started in the unvaccinated category (reference) and could contribute person-time to first, second and third doses. Over a median follow-up of 349 days, 12.7% (n=1632) remained unvaccinated, 54.1% (n=6953) received 3 doses, and 488 (3.8%) tested positive for SARS-CoV-2, (of which 260 [53.3%] had a clinically important outcome [i.e., hospitalization or death]). Adjusted vaccine effectiveness against infection was 31% (95% CI: 2, 51%), 46% (95% CI: 21, 63%), and 72% (95% CI: 43, 86%) for one, two, and three doses. Vaccine effectiveness against clinically important outcomes was 38% (95% CI: 4, 61%), 54% (95% CI: 23, 73%) and 67% (95% CI: 11, 87%). Vaccine effectiveness in solid organ transplant recipients is lower than the general population, however, vaccine effectiveness improved following a third dose.
Naylor K, Kim SJ, Smith G, McArthur E, Kwong JC, Dixon SN, Treleaven D, Knoll GA. Am J Transplant. 2022; May 16 [Epub ahead of print].
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