A study published in the American Journal of Ophthalmology found that, regardless of uveitis history, COVID-19 vaccinations did not increase the risk of noninfectious uveitis (NIU).
Give me some background first.
The COVID-19 pandemic spurred a global effort to develop and distribute effective vaccines very quickly; as of November 2023, over two-thirds of the global population had received at least one dose of a COVID-19 vaccine.
COVID-19 vaccines include:
- Messenger RNA vaccines (BNT162b2 [Pfizer-BioNTech]; mRNA-1273 [Moderna])
- Vector vaccines (Ad26.COV2 [Janssen, Johnson & Johnson]; ChAdOx1 nCoV19/AZD1222 [Oxford–AstraZeneca])\
- Protein subunit vaccines (NVX-CoV2373 [Novavax])
- Whole virus vaccines (PiCoVacc [Sinovac]; BBIBP-CorV [Sinopharm])
Due to the required speed with which these vaccines were developed and administered, however, the side effects of COVID-19 vaccines are still undergoing investigation.
Tell me about some of these side effects.
Reported ocular side effects—both newly developed and a worsening of existing conditions—of COVID-19 vaccines include:
And this is where the study comes in?
Yep! The authors noted that most of these case reports linked uveitis to the COVID-19 vaccination due to the occurrence of uveitis within 30 days of vaccination.
However, these incidences of vaccination-associated uveitis manifested differently in patients with a history of uveitis than in those without.
Tell me more.
Through a nationwide population-based cohort study, the researchers investigated the risk of NIU following COVID-19 vaccination.
Who was included?
Using data collected from the Korea Disease Control and Prevention Agency (KCDA) and the National Health Insurance Service (NHIS) database in South Korea, the study included a random sample of 7,917,457 individuals who were vaccinated against COVID between January 2021 and March 2022, with no recorded history of COVID-19.
Excluded individuals were those who had received NVX-CoV2373, those with incomplete vaccine data, and those diagnosed with uveitis and treated with corticosteroids in the year prior to their first COVID-19 vaccination.
The cohort was grouped into control and uveitis based on their history, and three groups were formed:
- Matched cohort study
- 218,796 individuals in the control group
- 72,932 individuals in the uveitis group
- Crossover case series analysis
- 7,697,738 in the control group
- 72,932 in the uveitis group
- Ad hoc analysis
- 180-day cumulative incidence: 75,545 patients who were treated with corticosteroids within one year prior to their first COVID-19 vaccination
- Separate crossover case series analysis: 75,327 patients who were treated with corticosteroids within 18 and 6 months prior to their first COVID-19 vaccination
So what were they looking for?
The incidence and risk of NIU that required treatment with corticosteroids as well as the incidence rate ratio (IRR), a comparison of the rate of uveitis 180 days before and after vaccination.
Findings?
In the crossover case series, the IRR did not show an increase in the incidence of recurrent uveitis over the 180-day period, nor did it show an increase when split into early and late periods.
In the matched cohort, the incidence rates of uveitis cases increased linearly over time.
Expert opinion?
A previous study performed by the authors suggested that COVID-19 vaccination, “Modestly increased the risk of non-anterior uveitis, with a history of noninfectious uveitis as the most significant risk factor.”
These results, the authors noted, differ from another population-based study, which found that the risk of active uveitis was increased by the administration of the BNT162b2 mRNA vaccine.
Limitations?
This study was retrospective and used ICD-10 codes and prescription data, so cases of mild uveitis would have been missed.
Take home.
“Our results demonstrate that COVID-19 vaccination itself did not increase the incidence of uveitis,” the study authors wrote.
If that had been the case, they noted, “it should have shown a rapid surge in the first few weeks after vaccination. However, this was not observed in either of the groups.”