

Īs a result, public health services around the world have implemented different strategies for rapid identification of both infected and asymptomatic carriers to prevent virus transmission. Moreover, although mortality from SARS-CoV-2 was found to be lower than that from SARS and MERS, COVID-19 deaths are greater in absolute number due to the higher transmissibility of this new virus. According to the latest WHO data, to date, more than 100 million cases and two million deaths from COVID-19 have been confirmed worldwide, challenging the healthcare systems all over the world. įrom December 2019 to today, the spread of SARS-CoV-2 infection has taken on the size of a pandemic. Our results should be interpreted with cautions due to several limitations in our study, mainly the small number of cases, lack of data on viral load and clinical setting.Īt the end of December 2019, a cluster of patients suffering from a new kind of pneumonia of unknown etiology has been observed in Wuhan (China) subsequently, it was attributed to a new virus (SARS-CoV-2), a beta-coronavirus phylogenetically similar to the causative agent of SARS, which determines the respiratory disease then called COVID-19. IgA levels seem to decline after 1 month since the onset of symptoms in mild cases. Severe patients showed a more vigorous IgA and IgG response.

Both IgA and IgG are maintained beyond 2 months. IgA and IgG antibody response is closely related, although seroconversion for IgA occurs earlier. Moreover, while IgG tended to stabilize, there was a relevant decline after the first month of IgA levels in mild cases. After stratifying for the severity of disease, both the IgA and IgG responses were more vigorous in severe cases. Prospective analysis conducted on 55 patients confirmed that IgA appear slightly earlier than IgG. Severe patients showed a higher IgA response compared with mild patients when analyzing optical density (8.3 versus 5.6, p < 0.001). Both IgA and IgG were maintained beyond 2 months.

Cross-sectional analysis showed that seroconversion for IgA seems to occur between days 6 and 15, while IgG response seems to occur slightly later, peaking at day 20 after symptoms onset.

Overall, 131 patients were considered with a total of 237 samples processed. Patients enrolled when admitted at the emergency department were prospectively followed up during hospital stay. We performed a cross-sectional analysis to determine the presence and the levels of both anti-SARS-CoV-2 IgG and IgA in a cohort of hospitalized patients with confirmed infection at different times in the natural history of the disease. A better understanding of the immune response in patients with SARS-CoV-2 infection could be important for identifying patients at greater risk of developing a more severe form of disease and with a worse prognosis. Antibody response plays a fundamental role in the natural history of infectious disease.
