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Authors: Wajnberg et al. 

Journal/ Pre-PrintmedXriv 

Key Words: Immunology, Antibodies 

Research Highlights 

  1. More than 90% of COVID-19 infected with mild-to-moderate COVID-19 experience robust IgG antibody responses against the viral spike protein 

  1. Titres are shown to be stable for at least three months and to correlate with neutralization of authentic SARS-CoV-2 


The vast majority of anti-SARS-CoV-2 antibody positive individuals are shown to have moderate to high titres of anti-spike antibodies. Neutralizing activities of 120 samples with known ELISA titres ranging from negative to highest titre level were subsequently assessed using a quantitative microneutralization assay based on authentic SARS-CoV-2. Neutralizing titres significantly correlated with spike-binding titres. 121 donors were recalled approximately 82 days post symptom onset to assess the longevity of the Ab response. Mild COVID-19 cases showed actually an increase in titre levels, while a slight drop was observed in donors with a previously higher titre range.  

Impact for SARS-CoV2/COVID19 research efforts  

Understand the immune response to SARS-CoV2/COVID19  

Treatment of SARS-CoV2/COVID19 positive individuals 

Study Type 

  • In vitro study 

  • Patient Case study 

Strengths and limitations of the paper 

Novelty: Shows that neutralizing antibody titres in moderately infected individuals are more stable than suggested in a number of other studies (e.g. Long et al. 2020) and even slightly increase in mild cases between day 30 and 82 post symptom onset 

Standing in the field:Contrasts previous findings in regard to waning antibody titre levels 8 weeks post symptom onset (Long et al. 2020)  

Appropriate statistics:Yes 

Viral model used:Sera of mildly infected individuals who have either been confirmed to have been infected by COVID-19 or are suspected to have been infected  

Translatability:Results suggest that COVID-19 infection results in titres of neutralizing antibodies which are stable for at least three months 

Main limitations:  

  • Many screened patients had their infection not confirmed by PCR and they only use their ELISA results to stratify their donors into anti-SARS-CoV-2 antibody positive or negative samples 

  • They show a significant correlation between antibody titres using ELISA and neutralization activity using their microneutralization assay. However, it would have been good to test neutralization activity also by the much more commonly used Plaque Neutralization Assay to confirm this correlation. As shown by another Mount Sinai preprint (Lee et al. 2020) not all sera with high SARS-CoV-2 antibody levels necessarily contain high neutralizing antibody levels 

  • Would have been good to include the SD or SEM in Figure 2A and B 

  • Correlates of protection for SARS-CoV-2 are still not known