A new research study detects pre-existing antibody-driven immunity against SARS-CoV-2 in some individuals, with higher rates in uninfected children.

Different age groups appear to have different responses to COVID-19, with kids often presenting with mild or no symptoms. However, the reason for this remains relatively unclear. 

Although COVID-19 is at the forefront of the news at present, there are multiple seasonal coronaviruses that infect people. More often than not, other coronavirus infections result in mild symptoms like the common cold. Due to the presence of these other coronavirus infections in the population, researchers developed an idea that some immunity may occur and potentially offer some protection against SARS-CoV-2. 

In a recent study published in Science, a group of London-based researchers has detected pre-existing antibody-driven immunity against SARS-CoV-2 (the virus that causes COVID-19). Scientists found this immunity in a small sample of uninfected individuals.

The study shows that 16 out of 302 adults (5.3%) had IgG antibodies that they likely developed during previous seasonal “common cold” coronavirus infections. It is thought that these cross-reacted with subunit S2 of the SARS-CoV-2 spike protein complex. 

The IgG antibodies were much more present in a cohort of uninfected children and adolescents (aged 1 to 16 years). 21 of these 48 subjects (43.8%) had detectable levels of SARS-CoV-2 S-reactive IgG antibodies.

IgG antibodies are the most common antibodies found in blood and other body fluids. This type of antibody protects against bacterial and viral infections. It can form after a person had had an illness or immunization. The viral S2 protein is responsible for cell entry and is thought to be similarly structured across different coronaviruses. 

These findings may provide insight into whether pre-established immunity to seasonal coronaviruses offers protection against SARS-CoV-2. It also goes some way to explaining lower COVID-19 susceptibility in children. 

The authors of the study advise that the results are vital to understanding people’s susceptibility to SARS-CoV-2. They discuss that the results can help drive research into a universal coronavirus vaccine if potential targets on S2 that are conserved across multiple coronaviruses are further explored. 

References:

EurekAlert!. 2020. Preexisting Antibodies Targeting SARS-Cov-2 Discovered In Small Proportion Of Uninfected Individuals. [online] Available at: [Accessed 19 November 2020].

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Tosif, S., Neeland, M.R., Sutton, P. et al. Immune responses to SARS-CoV-2 in three children of parents with symptomatic COVID-19. Nat Commun 11, 5703 (2020).

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