Abstract
The relationship between the nasopharyngeal virus load, IgA and IgG antibodies to both the S1-RBD-protein and the N-protein, as well as the neutralizing activity (NAbs) against SARS-CoV-2 in the blood of moderately afflicted COVID-19 patients, needs further longitudinal investigation. Several new serological methods to examine these parameters were developed, validated and applied in three patients of a family which underwent an ambulatory course of COVID-19 for six months. The virus load had almost completely disappeared after about four weeks. Serum IgA levels to the S1-RBD-protein and, to a lesser extent, to the N-protein, peaked about three weeks after clinical disease onset but declined soon thereafter. IgG levels rose continuously, reaching a plateau at approximately six weeks, and stayed elevated over the observation period. Virus-neutralizing activity reached a peak about 4 weeks after disease onset but dropped slowly. The longitudinal associations of virus neutralization and the serological immune response suggest immunity in patients even after a mild clinical course of COVID-19.
Highlights
According to our current understanding, coronavirus SARS-CoV-2, which causes COVID-19 [1,2], is transmitted among humans via droplets from the respiratory tract
SARS-CoV-2 RNA copies in swab samples observed over approximately five weeks, starting with with the onset of COVID-19
In a recent review [7], the acute antibody mediated response to Coronaviruses was described in detail
Summary
According to our current understanding, coronavirus SARS-CoV-2, which causes COVID-19 [1,2], is transmitted among humans via droplets from the respiratory tract. In a recent cell culture study, SARS-CoV-2 was isolated from the saliva of individuals over a period of two weeks after the onset of a symptomatic infection [3]. Further data from moderately ill patients, are important in terms of the length of time over which SARS-CoV-2 is excreted into the respiratory tract of these patients. Such data are important to know since most of the infections are mild, especially in young patients. Little is known about the course of the immune response with regard to the various types of antibodies against SARS-CoV-2 proteins and their virus-neutralizing potential over a prolonged period of time
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