Patients at risk of pulmonary fibrosis Post Covid-19: Epidemiology, pulmonary sequelaes and humoral response

Background The COVID-19 pandemic is one of the greatest public health problems. Our aims were to describe epidemiological characteristics, know the amount of protective antibodies and their permanence after a COVID-19 primary infection in patients with risk of pulmonary fibrosis. Methods Descriptive epidemiological and follow-up study of the humoral response in patients at risk of pulmonary fibrosis Post-Covid-19 hospitalized, between March and October 2020, and who were followed up for a one year after hospital discharge. Results 72 patients participated in the study, 52 showed pre-existing chronic comorbidities. COVID-19 clinical severity was rated in 6% mild, 58% as moderate and 36% as severe. After a year of follow-up, the forty percent had pulmonary sequelae, the most frequent (20%) was mild pulmonary fibrosis. Any case of reinfection was detected. All patients presented RBD IgG antibodies and 88% presented IgA antibodies after 8-9 months. The amount of RBD IgG was similar at 4-5 and 8-9 months post-Covid. There was no difference when level of RBD IgG according to the severity of the COVID-19 (p=0.441, p=0.594). Conclusions Mild pulmonary fibrosis sequelae is exceptional but was detected in a high percentage. The amount of RBD IgG is maintained throughout the convalescent phase and seems to protect against new reinfections despite of emerging viral variants. However, seems not predict the developed or not of pulmonary fibrosis.