No increased autoimmune risk after omicron, delta COVID-19 in boosted patients
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Key takeaways:
- In a mostly vaccinated cohort, COVID-19 infections amid the omicron and delta variant waves did not significantly elevate risks for autoimmune diseases.
- Subgroup analysis showed slightly increased risks for IBD, bullous skin disorders.
New diagnoses of autoimmune diseases were not overall more likely among vaccinated patients infected with omicron or delta variants of COVID-19, compared with those not infected, according to data published in JAMA Network Open.
“During the current era of COVID-19 endemicity dominated by milder omicron (B.1.1.529) variants and availability of COVID-19 booster vaccines, reduced severity of acute illness attributed to milder infection, and booster vaccination may potentially translate to lower long-term risk of post-acute autoimmune sequelae,” Liang En Wee, MPH, MRCP, of the National Center for Infectious Diseases, in Singapore, and colleagues wrote.
“However, while increased risk of autoimmune diseases after SARS-CoV-2 omicron variant infection has been observed across several retrospective population-based cohort studies, clinical evidence of the potential protection from vaccination has been mixed,” they added.
To investigate the risk for autoimmune sequalae from delta and omicron variants among vaccinated individuals, Wee and colleagues analyzed data from the national SARS-CoV-2 testing registry in Singapore, which has a “highly vaccinated population,” they wrote.
The researchers constructed two cohorts — one of adults infected with the SARS-CoV-2 delta or omicron BA.1 or BA.2 variants (n = 480,082), and a contemporaneous control group with negative test results (n = 1,285,954). The study included 1,766,036 adults (mean age, 49 years) who were predominantly Chinese (73.1%), Malay (13.7%) or Indian (9.9%) in ethnicity.
The researchers used the MediClaims national database to identify incident autoimmune sequelae, and estimated risks among cases vs. controls using Cox proportional hazards regression models. Study participants were followed from 30 days after the date of their first positive COVID-19 test to 300 days after that date.
According to the researchers, 81.1% of cases completed primary vaccination during the delta variant period — from September 2021 through November 2021 — and 74.6% of cases received boosters during the omicron variant period — from December 2021 through March 7, 2022. The analysis found no significantly elevated risks for any of 12 autoimmune sequelae for up to 300 days among people infected with either the omicron or delta variants.
However, among a subset of COVID-19 cases that required hospitalization during the omicron period, there were “modestly increased” risks for inflammatory bowel disease (adjusted HR = 2.23; 95% CI, 1.45-3.46) and bullous skin disorders (adjusted HR = 4.88; 95% CI, 2.47-9.66), according to the researchers. Additionally, during omicron, patients infected with SARS-CoV-2 who received only a primary vaccination series demonstrated an elevated risk for vasculitis (adjusted HR = 5.74; 95% CI, 1.48-22.23), but this risk was not increased among those who received boosters.
“These findings substantially differ from the majority of studies that have reported increased long-term incidence of a wide range of autoimmune sequelae after SARS-CoV-2 infection, albeit from waves of earlier SARS-CoV-2 variants and without accounting for the potential protection from COVID-19 vaccination, including boosters,” Wee and colleagues wrote.
“The results support the continued enrollment of at-risk individuals for booster vaccinations during COVID-19 endemicity,” they added. “Given persistent vaccine hesitancy, highlighting benefits may help increase acceptance, particularly as COVID-19 vaccination is likely to be protective against autoimmunity, rather than contributory.”
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