Abstract
ObjectiveTo follow serological immune responses of front-line healthcare workers after PCR-confirmed COVID-19 for a mean of 30 weeks, describe the time-course of SARS-CoV-2 spike protein-specific IgG, IgA and IgM levels and to identify associations of the immune response with symptoms, demographic parameters and severity of disease.MethodsAnti-SARS-CoV-2 S protein-specific IgG, IgA and IgM antibodies were measured at three time points during the 30-week follow-up. COVID-19-specific symptoms were assessed with standardized questionnaires.Results95% of the participants mounted an IgG response with only modest decline after week 12. IgG-type antibodies were still detectable in almost 90% of the subjects at 30 weeks. IgA and IgM responses were less robust and antibody titers decreased more rapidly. At 30 weeks, only 25% still had detectable IgA-type and none had IgM-type antibodies. Higher age and higher disease severity were independently associated with higher IgG antibody levels, albeit with wide variations.ConclusionSerological immune responses after COVID-19 show considerable inter-individual variability, but show an association with increasing age and higher severity of disease. IgG-type anti-SARS-CoV-2 antibodies remain positive in 90% of the individuals 30 weeks after onset of symptoms.
Highlights
The severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) was first isolated in January 2020 in the province of Wuhan, China, where clusters of severe atypical pneumonias with respiratory failure (COVID-19) had been noticed from December 2019 on [1, 2]
Similar to other viral respiratory infections, patients infected by SARS-CoV-2 generally mount an immune response with virus-specific IgM, IgA and IgG antibodies, but anti-SARS-CoV-2 antibody titers appear to vary considerably between individuals [4,5,6]
Previous investigations have shown that respiratory coronaviruses causing common colds usually elicit only weak immune responses that wane rapidly [7]
Summary
The severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) was first isolated in January 2020 in the province of Wuhan, China, where clusters of severe atypical pneumonias with respiratory failure (COVID-19) had been noticed from December 2019 on [1, 2]. Similar to other viral respiratory infections, patients infected by SARS-CoV-2 generally mount an immune response with virus-specific IgM, IgA and IgG antibodies, but anti-SARS-CoV-2 antibody titers appear to vary considerably between individuals [4,5,6]. It is so far unknown how long immunity against SARS-CoV-2 persists in patients who recovered from the infection. Previous investigations have shown that respiratory coronaviruses causing common colds usually elicit only weak immune responses that wane rapidly [7]. While some reports indicated rapidly waning antibody titers [9,10,11], others found a slower decline [6, 12, 13]
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