A study of 1.8 million adults published in JAMA Network Open suggests that—except for a slightly higher risk of inflammatory bowel disease and blistering skin disorders in a subgroup hospitalized for SARS-CoV-2 Omicron variant infection—Delta or Omicron BA.1 or BA.2 infection in highly vaccinated adults doesn't significantly raise the long-term risk of autoimmune diseases.
Led by investigators from the National Centre for Infectious Diseases in Singapore, the study team used the SARS-CoV-2 registry and a healthcare claims database to compare the long-term risk of new autoimmune diseases after Delta or Omicron BA.1 or BA.2 infection in recipients of COVID-19 vaccines and boosters with that in uninfected controls. The study period was September 2021 to March 2022, with a 300-day follow-up.
Of all participants, 27.2% had COVID-19, 72.8% were controls, 51.9% were women, and the average age was 49 years.
"Studies have reported increased risk of autoimmune sequelae after SARS-CoV-2 infection," the researchers wrote. "However, risk may potentially be attenuated by milder Omicron (B.1.1.529) variant infection and availability of booster vaccination."
Boosters may lower risk of new autoimmune disease
During Delta predominance, 104,179 participants had COVID-19 infections and 666,575 were controls, while 375,903 and 619,379 controls, respectively were infected during Omicron predominance. A total of 81.1% of infected participants had completed the primary two-dose COVID-19 mRNA vaccine series amid the Delta era, and 74.6% received boosters during the Omicron period.
Continued surveillance for autoimmune conditions arising after COVID-19 is still necessary during the Omicron variant era.
A significantly higher risk of 12 studied autoimmune diseases wasn't observed during the Delta or Omicron periods, except for inflammatory bowel disease (adjusted hazard ratio [aHR], 2.23) and bullous (blistering) skin disorders (aHR, 4.88) in hospitalized COVID-19 patients amid Omicron. An elevated risk of vasculitis was documented in vaccinated Omicron patients (aHR, 5.74) but not those who received boosters.
The study authors concluded, "Continued surveillance for autoimmune conditions arising after COVID-19 is still necessary during the Omicron variant era."