Investigators studied the rates of noninfectious uveitis (NIU) in people who received the initial doses of the BNT162b2 mRNA COVID-19 vaccine, and then compared them with historic NIU rates.
Study design
This is a retrospective population-based study using data of 2.6 million people enrolled in a large health maintenance organization in Israel who received the first BNT162b2 mRNA COVID-19 vaccine dose between December 2020 and April 2021 and 2.4 million people who received the second vaccine dose between January 2021 and April 2021. Events of active NIU, defined as whether topical or oral corticosteroids had to be initiated or increased to control inflammation, were included if they occurred within 21 days following either vaccine dose.
Outcomes
The observed number of cases of active NIU (either new or flare-up of prior disease) occurring after the COVID-19 vaccine was given were compared to the expected number of cases, based on estimation from historic data. After the first and second doses, 100 and 88 cases of NIU, respectively, were found, translating into a 21-day overall risk of 3.85 cases/100,000 and 3.61 cases/100,000 vaccinated individuals, respectively. Based on the number of NIU cases in 2019 as a reference, the adjusted standardized incidence ratio (SIR) following the first dose of the vaccine was 1.41, with an attributable risk of 1.12 cases/100,000 vaccinated individuals. Following the second dose, the SIR was 1.31, with an attributable risk of 0.86 cases/100,000 vaccinated individuals. Anterior uveitis was the most common site of inflammation, occurring in 91% of cases.
Limitations
The effect size and increase in SIR was relatively small after the first and second doses, and the low numbers of people who developed NIU makes it difficult to establish cause and effect. There may be surveillance bias as well, with both individuals seeking care after vaccination and ophthalmologists monitoring for uveitis. Interestingly, the cohort had a high incidence rate of patients with prior uveitis (0.7%), which may make it difficult to generalize findings.
Clinical significance
The incidence of new NIU or flare-up of prior disease remains small. Patients with a history of uveitis should be made aware of the risks of relapse in the context of their disease, and ophthalmologists may choose to monitor these patients closely when additional doses of vaccine are received. The public health benefits, as the authors acknowledge and discuss, overwhelmingly favor vaccination.