Severe COVID linked to more self-attacking antibodies, study says
Hospitalized COVID-19 patients were more likely to have autoantibodies, or self-attacking antibodies, than those without COVID-19, according to a study today in Nature Communications.
The researchers looked at March and April 2020 blood samples from 147 COVID-19 patients at Stanford-affiliated hospitals, as well as 48 patients from Kaiser Permanente in California, although most of the study’s assessments didn’t involve the whole cohort.
By using three protein arrays to look at immunoglobulin G (IgG) autoantibodies, the researchers found that about 50% of patients had autoantibodies, compared with less than 15% of samples from healthy controls collected pre-pandemic from donors. Longitudinal analysis from 48 patients also showed that about 20% of patients had new autoantibodies within a week of COVID-19 hospitalization.
Data indicated that antibodies recognizing nonstructural COVID-19 proteins were positively correlated with autoantibodies and that autoantibodies were produced out of proportion to the total IgG serum concentration. Also, in most people, only a small number of autoantigens were targeted.
Some of the autoantibodies have also been seen in relatively rare connective tissue diseases and are not typically measured. Others were anti-cytokine antibodies (ACAs) that the researchers say may have been triggered by SARS-CoV-2 infection or an inflammatory immune response to it; about 60% to 80% of the cohort had at least one ACA.
“It’s possible that, in the course of a poorly controlled SARS-CoV-2 infection—in which the virus hangs around for too long while an intensifying immune response continues to break viral particles into pieces—the immune system sees bits and pieces of the virus that it hadn’t previously seen,” said senior author PJ Utz, MD, in a Stanford Medicine press release. “If any of these viral pieces too closely resemble one of our own proteins, this could trigger autoantibody production.”
Gabon may have had lower COVID-19 severity, analysis suggests
An analysis of the single hospital treating COVID-19 patients in Gabon showed that from March to June 2020, 62.6% of patients were asymptomatic, 33.7% had mild symptoms, and 3.7% had severe illness, according to a study today in JAMA Network Open. The mortality rate was 1.4%.
By the end of the study period, the researchers say 3,463 patients in the country had COVID-19, but the study consisted only of the 837 admitted to the Armed Forces Hospital in Libreville, Gabon. Most (68.3%) were men, and the median age was 35 years. COVID-19 severity was associated with older age (mean age 46.1 years vs 41.3, but 35.7 years in mild and asymptomatic cases). Diabetes was also seen more frequently in patients with severe COVID-19 (16.1% of 31), compared with patients with mild (3.9% of 282) or asymptomatic illness (0.9% of 524).
Flu-like symptoms were more common in patients with mild symptoms (20.2%) than in patients with severe symptoms (0%) or those who were asymptomatic (0%). Also, while there was no significant difference between men’s and women’s advanced thoracic computed tomography scores for stages I to III, men were more likely to have a stage IV score than women (6.7% of 193 vs 1.0% of 196; odds ratio, 6.9).
The researchers suggest that the lower rates of severe illness may be due to the country’s smaller number of older and more vulnerable people. However, as a related commentary by Igho Ofotokun, MD, and Anandi N. Sheth, MD, points out, these findings must be taken into context with its early timeframe in the pandemic, the country’s limited COVID-19 testing, and the study’s single-site design.
“The silver lining in this report and the African COVID-19 experience is that the window of opportunity still exists to protect one of the most vulnerable regions of the world from the catastrophes of this pandemic through massive and rapid vaccination,” Ofotokun and Sheth conclude.
Sep 14 JAMA Netw Open study and commentary