Omicron subvariants of COVID-19 that may be able to evade vaccine immunity are on the rise in Victoria. Health authorities have issued a warning that just like NSW and Queensland they’re on track to be the state’s dominant COVID-19 strains.
Vaccine-resistant strains on the rise
Omicron subvariants BA.4/BA.5 appear to escape antibody responses among people who had previous COVID-19 infection and those who have been fully vaccinated and boosted, according to new data from researchers at Beth Israel Deaconess Medical Center, of Harvard Medical School.
The research published in the New England Journal of Medicine stated that “The levels of neutralizing antibodies that a previous infection or vaccinations elicit are several times lower against the BA.4 and BA.5 sub-variants compared with the original coronavirus.”.
“We observed 3-fold reductions of neutralizing antibody titers induced by vaccination and infection against BA4 and BA5 compared with BA1 and BA2, which are already substantially lower than the original COVID-19 variants,” Dr. Dan Barouch, an author of the paper and director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, reported to CNN.
That said, current COVID-19 vaccine formulations are still expected to provide protection against severe disease.
BA.4/BA.5 around the world
Subvarinats BA.4/BA.5 have caused ~35% of new COVID-19 infections in the United States last week, according to data shared by the US Centers for Disease Control and Prevention.
BA.4/BA.5 are the fastest spreading variants reported to date, and they are expected to dominate COVID-19 transmission in the United States, United Kingdom and the rest of Europe within the next few weeks, according to the European Centre for Disease Prevention and Control.
Victoria’s response
Chief Health Officer, Brett Sutton, warns BA.4/BA.5 strain traces have risen in recent weeks, and have a greater ability to evade vaccine immunity.
“Traces of the BA.4/BA.5 strain in Victoria’s metro and regional wastewater have risen significantly in recent weeks, indicating increasing transmission of this sub-lineage in the community,” Minister Sutton, said in a statement on Saturday.
He also stated that the BA.4/BA.5 subvariants accounted for 17% of Victorian infections and were forecast in coming weeks to overtake BA.2 to become the state’s dominant strain.
“The Department of Health anticipates the prevalence of BA.4/BA.5 in Victoria is likely to result in an increase in cases, including reinfections, and hospital admissions,” he said.
Currently, there is no evidence that suggests these sub-variants caused more severe disease.
Awaiting a vaccine update
As discussed in an earlier blog post, an updated version of Moderna’s COVID-19 vaccine is well underway which increases antibody levels 8-fold against the Omicron variant (according to early trial results).
Termed as a ‘bivalent booster’, it will contain components of both Moderna’s original COVID-19 vaccine and a vaccine that targets the Omicron variant(s).
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