01-07-21 05:30:00, Coronavirus variants: Escape from antibody classes 1 to 3 (SPR, based on Greaney et al.)
So far, no variant has achieved escape from all three major antibody classes.
Please note: This is a scientific analysis; it does not support “fear mongering”.
Existing coronavirus variants – including the British, South African, Brazilian and Indian variants – have shown some gradual changes in infectiousness, virulence, and immune escape. Relative transmission advantages are often only transitory, until collective immunity has caught up.
Some of the existing variants – notably the South African, Brazilian (P1), Nepalese and Peruvian variants – have managed to escape two out of three major antibody classes, reducing vaccine effectiveness; but so far, no variant has managed to escape all three antibody classes (see above).
Such a triple-escape variant may arrive next autumn or winter and could potentially lead to increased rates of vaccine breakthroughs and re-infections, especially in regions that have not yet faced the Brazilian or South African ‘class 2’ escape variants. The actual impact will also depend on the effectiveness of cellular immunity (T cells), which may be somewhat broader.
Furthermore, a triple-escape variant will, for the first time, raise the question of a potential antibody-dependent disease enhancement (ADE), as vaccinated people, in particular, will have very high levels of non-neutralizing antibodies, whose behavior remains somewhat uncertain. ADE has been observed with SARS-1 vaccine candidates, but not yet with SARS-2 vaccines.
In terms of escape mutations, the coronavirus has already played many of its best ‘cards’, including the powerful 484 escape mutation found in the South African, Brazilian and New York variants and the 490 mutation in the Peruvian variant. In terms of receptor binding affinity – which may or may not increase infectiousness and virulence – there are a few more options left (see charts below).
Existing and future coronavirus variants once again highlight the importance of effective and affordable early treatment options for high-risk people and low-income nations, as monoclonal antibody therapies are losing effectiveness and vaccines will require updated boosters.