An interesting unedited manuscript published in Nature on 8th July by Planas and others researched this issue.
The Delta variant was identified in October 2020 in India.
It has since then become dominant in some Indian regions and the United Kingdom and further spread to many countries.
This lineage includes three main subtypes harbouring diverse spike mutations in the N terminal domain and the receptor binding domain which may increase their immune evasion potential.
The Delta variant is believed to spread faster than other variants.
In this study, they isolated an infectious Delta strain from a traveller returning from India.
They examined its sensitivity to monoclonal antibodies and to antibodies present in serum from COVID-19 convalescent individuals or vaccine recipients, in comparison to other viral strains.
They found that the variant Delta was resistant to neutralisation by some anti-NTD and anti-RBD antibodies including Bamlanivimab, which were impaired in binding to the spike.
Sera from convalescent patients collected up to 12 months post symptoms were fourfold as potent against the variant Delta, relative to variant Alpha. Sera from individuals having received one dose of Pfizer or AstraZeneca vaccines barely inhibited variant Delta. Administration of two doses generated a neutralising response in 95% of individuals, with titres 3-5 fold lower against Delta than Alpha. Thus, variant Delta spread is associated with an escape to antibodies targeting non RBD and RBD spike epitopes.
The London General Practice provides a complete service for all aspects of SARS-CoV-2 infection and COVID-19.
As the London leading doctors’ clinic, it undertakes all forms of testing including fit to fly, test for release, lateral flow antigen and a rapid PCR swab service.
Dr Paul Ettlinger
BM, DRCOG, FRCGP, FRIPH, DOccMed