Why 4th wave may be a little far away
This sublineage has one specific mutation in the RBD: a substitution of lysine for glutamine at position 452 (L452Q).
This is notable for two reasons. First, L452Q has been previously identified in several variants of concern, like Lambda, Delta, Delta plus, and Epsilon
Second, unlike many mutations where we must only speculate on their impact on viral fitness, L452Q was studied and found to increase escape immunity, allowing the virus to attach more strongly to human cells and avoid neutralizing antibodies
The second mutation is more mysterious. It is a substitution from serine to leucine at position 704 (S704L). Unlike L452Q, S704L is a relatively rare mutation by way of major variants, and its exact impact on the virus is unstudied
Based on its position in the S2 region of the Spike protein, we can speculate that the mutation may affect either viral fusion or furin cleavage efficiency, but further study would be welcome
We can say with near certainty that BA.2.12.1 is at least as transmissible and immune evasive as BA.2. It is unlikely that the two Spike mutations would decrease either of these facets of the virus strain
However, due to the wealth of BA.2 cases in previous months, the BA.2.12.1 virus may be impeded by antibodies developed from infections during that wave, which could explain why cases are low relative to the Omicron wave
It is critical to remain vigilant in our surveillance of these subvariants. Recent reports from Hong Kong note that Omicron BA.2 subvariants deliver a similar fatality risk to those infected relative to earlier strains of SARS2
This is contrary to many assumptions that Omicron is less severe than previous strains. Additionally, there are indications that Omicron is as dangerous in terms of long-term complications in children as the Delta variant of last summer
A new wave of Omicron with BA.2.12.1 or another variant yet to be identified could be as catastrophic as the wave caused by earlier VOCs including Delta
So, which sub-variant is the fittest? BA.2.12.1, BA.4 or BA.5? While the latter two are surging in SouthAfrica & Europe, the former is making strongholds in the US. Let’s wait & see, but be vigilant!! more