To assess changes in test positivity rates for Guillain-Barre syndrome (GBS)-associated ganglioside antibodies during the COVID-19 pandemic at a national clinical laboratory.

Case reports have suggested a temporal association between SARS-CoV-2 infection and subsequent occurrence of GBS, but subsequent studies produced conflicting results regarding the incidence trends of GBS during the COVID-19 pandemic. More than half of reported GBS cases have identifiable antibodies present to various gangliosides. This high frequency allows for the examination of the potential association of the COVID-19 pandemic with different forms of GBS-associated antibodies.

This cross-sectional observational study assessed quarterly test volume and positivity rates for GQ1b, GM-1, GD1a, and GD1b for tests performed January 2016, through March 2021, at Quest Diagnostics. Pandemic period was defined as March 2020 through March 2021.

Positivity rates on ganglioside antibody tests during the study period were 2.6% (660 positive/25,006 tested) for GQ1b; 17.2% (7734/45,040) for GM-1; 7.1% (1390/19,711) for GD1a; and 2.9% (556/18,959) for GD1b. Relative to pre-pandemic levels, positivity rates during the pandemic declined by 61% for GQ1b (3.1%, 95% CI 2.9-3.4% pre-pandemic; 1.2%, 95% CI 0.9-1.4% during the pandemic, p<0.001) and 24% for GM-1 (18.2%, 95% CI 17.8-18.6% vs 13.8%, 95% CI 13.2-14.5%; p<0.001); however, GM-1 positivity rates also declined significantly in each of the prior two years. There was no significant change in positivity rates during the pandemic for GD1a (compared to entire pre-pandemic period) or GD1b (compared to the prior two years).

These findings from a national clinical laboratory suggest heterogeneity in the association of the COVID-19 pandemic with positivity rates of GBS-associated ganglioside antibodies. Mitigation strategies taken during the pandemic may have reduced the frequency of certain forms of GBS, such as those mediated by GQ1b and GM-1.