Changes in ANA Positivity Following SARS-CoV-2 Outbreak in Lombardy Region, Italy

Area of Science:

• Immunology
• Infectious Diseases
• Epidemiology

Background:

• The COVID-19 pandemic has raised concerns about potential autoimmune responses.
• Antinuclear antibodies (ANA) are indicators of systemic autoimmunity, with emerging evidence suggesting increased prevalence post-infection.

Purpose of the Study:

• To assess ANA positivity rates and distribution patterns before and after the COVID-19 pandemic onset in Lombardy, Italy.
• To evaluate the association between ANA and SARS-CoV-2 infection, hospitalization, sex, and age.

Main Methods:

• Historical analysis of 1879 matched SARS-CoV-2 RT-PCR and ANA records (March 2020 - December 2023).
• ANA assessment via indirect immunofluorescence (IIF) on HEp-2 cells, classified by ICAP.
• Comparison with pre-pandemic (2019) data; cumulative risk and Cox regression analyses.

Main Results:

• ANA positivity increased significantly during the pandemic (42.4%) compared to 2019 (29.9%, p < 0.00001).
• SARS-CoV-2 positive individuals showed higher ANA positivity (12.9% vs 6%, OR: 2.31, p < 0.001).
• SARS-CoV-2 infection, female sex, hospitalization, and age were independently associated with ANA positivity risk. Risk was higher with earlier SARS-CoV-2 variants.

Conclusions:

• SARS-CoV-2 infection is associated with an increased cumulative risk of ANA positivity in the Lombardy population.
• The risk of ANA positivity was particularly elevated during the initial phases of the pandemic, linked to earlier variants.
• The nuclear anti-topo I-like [anti-cell (AC)-29] pattern was more prevalent in SARS-CoV-2 positive individuals.