New Study Reveals Pre-existing Antibody-driven Immunity Against SARS-CoV-2

Findings on Immunity in Different Age Groups

A recent research study has identified pre-existing antibody-driven immunity against SARS-CoV-2 in certain individuals, with notably higher rates observed in uninfected children. The study highlights that responses to COVID-19 can vary significantly across different age groups, particularly with children often exhibiting mild or no symptoms, although the underlying reasons remain unclear.

Context of Seasonal Coronaviruses

While COVID-19 continues to dominate headlines, it is important to recognize that multiple seasonal coronaviruses also infect the human population. Typically, these infections lead to mild symptoms similar to those of the common cold. Researchers have posited that immunity from these other coronavirus infections may provide some degree of protection against SARS-CoV-2.

Details of the Research Study

Published in the journal Science, the study conducted by a team of researchers in London discovered pre-existing antibody-driven immunity against SARS-CoV-2 in a small group of uninfected individuals. Among the 302 adults tested, 16 (5.3%) were found to have IgG antibodies likely developed from previous infections with seasonal coronaviruses. These antibodies are believed to cross-react with the subunit S2 of the SARS-CoV-2 spike protein complex.

In contrast, a more significant proportion of uninfected children and adolescents (aged 1 to 16 years) exhibited this immunity. Specifically, 21 out of 48 subjects (43.8%) demonstrated detectable levels of SARS-CoV-2 S-reactive IgG antibodies.

Role of IgG Antibodies

IgG antibodies are the most prevalent antibodies found in blood and other body fluids. They play a crucial role in defending the body against bacterial and viral infections, forming in response to illness or vaccination. The S2 protein of the virus is essential for cell entry and is believed to share structural similarities across various coronaviruses.

Implications of the Findings

These findings could shed light on whether pre-established immunity to seasonal coronaviruses contributes to protection against SARS-CoV-2. Additionally, they may help explain the lower susceptibility of children to COVID-19.

The authors of the study emphasize the importance of these results in understanding susceptibility to SARS-CoV-2. They suggest that these insights could inform future research aimed at developing a universal coronavirus vaccine, particularly if conserved targets on the S2 protein across multiple coronaviruses are further investigated.

References

EurekAlert!. 2020. Preexisting Antibodies Targeting SARS-Cov-2 Discovered In Small Proportion Of Uninfected Individuals. [online] Available at: [Accessed 19 November 2020].
Ng, K., Faulkner, N., Cornish, G., Rosa, A., Harvey, R., Hussain, S., et al. 2020. Preexisting and de novo humoral immunity to SARS-CoV-2 in humans. Science, p.eabe1107.
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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