key: cord-0861702-5vxo6wqt
authors: Mi, Bobin; Chen, Lang; Panayi, Adriana C.; Xiong, Yuan; Liu, Guohui
title: Serum Mycoplasma Pneumoniae IgG in COVID-19: A Protective Factor
date: 2020-04-17
journal: nan
DOI: 10.1101/2020.04.12.20060079
sha: 2f767e284b57d46a211b3f11405bffa645eb060b
doc_id: 861702
cord_uid: 5vxo6wqt

Abstract Background: A correlation between prior exposure to Mycoplasma pneumoniae (IgG positive) and better clinical response to COVID-19 was elusive. Methods: A retrospective review of all COVID-19 infected patients treated at Wuhan Union Hospital from Feb 1 to Mar 20 was carried out. Continuous variables were described as mean, median, and interquartile range (IQR), while categorical variables were compared by X2 test or Fisher's exact test between COVID-19 infected patients with mycoplasma lgG (-) and mycoplasma lgG (+). Results: Statistically significant differences were shown in terms of laboratory test results. COVID-19 infected patients with mycoplasma lgG positivity had a higher lymphocyte count and percentage (p=0.026, p=0.017), monocyte count and percentage (p=0.028, p=0.006) and eosinophil count and percentage (p=0.039, p=0.007), and a lower neutrophil count and percentage (p=0.044, p=0.006) than COVID-19 infected patients without mycoplasma lgG. Other routine blood tests, including coagulation tests, blood biochemistry and infection-related biomarkers did not significantly differ except for thrombin time (p=0.001) and lactate dehydrogenase (p=0.008). Furthermore, requirement and use of a nasal catheter or oxygen mask was significantly lower in COVID-19 infected patients with mycoplasma lgG positivity (p=0.029). Conclusions: Our findings indicate that mycoplasma IgG positivity is a potential protective factor for SARS-CoV-2 infection.

Ever since its initial outbreak in Wuhan, Hubei province, China, in December 2019, the 2019 novel coronavirus disease (COVID-19) has quickly spread around the world.

Currently, more than 1.3 million cases have been confirmed, with 76,420 deaths worldwide. 1 The clinical characteristics of patients with COVID-19 have been well described with some risk factors shown to increase the mortality of COVID-19 identified, including diabetes, cancer and aging. 2, 3 Protective factors that may help patients with COVID-19 show fewer severe symptoms and better recovery remain elusive. As frontline medical personnel in the Wuhan Union Hospital-one of the biggest COVID-19 designated institutions in Wuhan-we have unique first hand experience in dealing with this pandemic. Here, we report a correlation between prior exposure to Mycoplasma pneumoniae (IgG positivity) and better clinical response to COVID-19. This association has, to the best of our knowledge, not been previously shown. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint . https://doi.org/10.1101/2020.04.12.20060079 doi: medRxiv preprint p=0.006) than COVID-19 infected patients without mycoplasma lgG. Other routine blood tests, including coagulation tests, blood biochemistry and infection-related biomarkers did not significantly differ except for thrombin time (p=0.001) and lactate dehydrogenase (p=0.008). Furthermore, requirement and use of a nasal catheter or oxygen mask was significantly lower in COVID-19 infected patients with mycoplasma lgG positivity (p=0.029), suggesting a better prognosis. The rate of noninvasive ventilation and mortality did not differ; this may be due to lack of relevant clinical cases.

Patients with prior exposure to Mycoplasma pneumoniae (IgG positive) showed stronger resistance and better recovery from the SARS-CoV-2 viral infection than patients without exposure. Of particular note, the immune response rendered against the virus was noted to be stronger in the IgG positive group, evident through an overall higher leukocyte count. This can partially be explained by reprogrammed immune cells. 4 Prior evidence has supported that when the lungs recover from infection they develop new alveolar macrophage biology, which can protect the lungs of adults against pneumonia. 5 Our retrospective patient review highlighted a similar phenomenon: COVID-19 patients with IgG positivity displayed milder symptoms and rarely experienced severe disease (OR, 2.31; 95% CI, 1.89-3.02). To eliminate the interference of age, we compared the outcomes of elder patients (> 60 years) and Normal ranges for the laboratory values are as follows: white blood-cell count, 3.5-9.5x10 9 /L; hemoglobin, 

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