NEXT COVID WAVE: Experts Eye New Elusive Sub-Variants BA.4 and BA.5 [Updated]

Heirs apparent

BA.4 and BA.5 aren't new; they were first seen causing a massive wave of infection in South Africa in mid-to-late April that peaked in mid-to-late May. BA.4 and BA.5 are often clumped together because they share the same mutations in their spike protein, though they have different mutations elsewhere in their genetic blueprints. The spike protein is the critical protein that SARS-CoV-2 uses to latch onto human cells and, as such, is the prime target of vaccine- and infection-based immune responses.

BA.4 and BA.5 have a lot of unappealing qualities that have experts wary. First, the duo has a clear transmission advantage over BA.2.12.1, according to recent analyses of head-to-head comparisons of BA.4/5 to BA.2.12.1. They are poised to overcome BA.2.12.1 in the US, potentially causing yet another wave. 

 

Next wave —

With BA.2.12.1 now dominant in US, experts eye new subvariants BA.4 and BA.5 [Updated]

New data suggests BA.4, BA.5 are better at evading immune responses than BA.2.12.1.

[Image: Thomas Trutschel]

Beth Mole - 6/7/2022, 11:00 AM

"...A recent preprint study posted by researchers in Japan reported that BA.2.12.1, BA.4, and BA.5 replicate better in human lung cells than the previous reigning subvariant, BA.2. But, BA.4 and BA.5 cause more severe disease in hamsters than both BA.2 and BA.2.12.1.

The study also found that BA.4 and BA.5 can evade neutralizing antibodies generated from BA.1 and BA.2 infections. That means that people who have recovered from previous omicron infections may not have optimal protection from BA.4 and BA.5.

Additionally, another recent preprint study by researchers at Columbia University reported that BA.4 and BA.5 are better able to thwart immune responses in vaccinated and boosted people than BA.2 and BA.2.12.1. Specifically, BA.2.12.1 was 1.8-fold more resistant to the antibodies from vaccinated and boosted people than BA.2. But, BA.4 and BA.5 were collectively 4.2-fold more resistant. Though vaccines and boosters continue to provide strong protection against severe disease and death, the authors concluded that the rise of BA.4 and BA.5 "is likely to lead to more breakthrough infections in the coming months."