COVID-19: Omicron BA.4 and BA.5 subvariants

The BA.4 and BA.5 COVID-19 subvariants are the reason for the current global spike of cases.

The main characteristic of these subvariants, is that they can spread faster than other circulating variants — mostly BA.2, which caused a surge in cases at the beginning of the year.

Tyson Graber, associate scientist at the CHEO Research Institute and co-lead of Ottawa’s wastewater project, said the Omicron sub-variants are driving high rates of transmission and hospitalization in parts of Europe and elsewhere.

Those Omicron sub-variants include BA.4, BA.5 and BA2.12.1.

BA.4/BA.5 are significantly more contagious than previous Omicron sub-variants. There is also a more significant capability to evade immunity from vaccines and previous illness.

Some reports suggest that BA.5 is more virulent than previous Omicron sub-variants and more likely to infect the lungs.

Re-infections

“Reinfections are going to be pretty inevitable until we have vaccines or widespread mandates that are going to prevent cases rising again. But the good news is that we are in, I think, a much better spot than we were without the vaccines,” said Pavitra Roychoudhury, an acting instructor at the University of Washington’s Department of Laboratory Medicine and Pathology.

Experts say BA.4 and BA.5 appear to be better able to evade the immunity people have built up from getting sick from COVID-19 previously or getting vaccinated.

Evading immunity – Pathogenicity

“The concern is that this appears to be another highly infectious variant that seems to be better at evading prior-infection immunity and vaccine-induced immunity than prior versions. So even infection with prior Omicron may not be protective,” Matthew Fox, a professor of epidemiology and global health at Boston University, said in an e-mail.

“That said… while it may be more severe than the prior Omicron variant (and we don’t have great data on that yet) it doesn’t appear to be much more severe and Omicron in general is less severe.”

Eric Liang Feigl-Ding, public health scientist who is currently an epidemiologist and Chief of COVID Task Force at the New England Complex Systems Institute shared these diagrams that suggest a couple of worrying facts.

⚠️Very worried about #BA5 causing #COVID19 hospitalization surges everywhere it goes—bad it’s very past-immunity-evasive. Portugal hit 80-90% of its old hospitalization peak recently. UK hospitals strained to the brink now too. Bad trends many in places.🧵

HT @jburnmurdoch pic.twitter.com/8MZUOyUglN

— Eric Feigl-Ding (@DrEricDing) June 27, 2022

George Atsalakis, associate professor at the Technical University of Crete – Greece, suggested that BA.2.12.1, bypasses immunity almost twice as much as BA.2 even the booster dose. BA.4 & BA.5 bypass immunity more than 4 times more than BA.2.

The latest CDC update shows that we have 35% of new cases corresponding to variants BA.4, BA.5, which have the highest immune escape of any since the onset of the pandemic and 56% of BA.2.12 .1.

Symptoms and Long Covid recent research shows that Omicron subcategories cause more symptoms and more impact on daily activities.

New data suggest that BA.4 & BA.5 are more contagious than BA.2. The symptoms after the disease in many patients persist for a long time.

A recent survey shows 50-70% less Long Covid with Omicron compared to Delta. But because the number of infections with Omicron and its variants is significantly higher than any previous wave, including the Delta, the risk of appearing in absolute numbers in Long Covid may be even higher.

Another feature of Omicron is re-infections. Before Omicron, re-infections were below 1%. The risk of re-infection is significantly increased due to the new spike mutations to which we are exposed. BA.2.12.1 showed the L452Q mutation and BA.4, BA.5 added 2 other basic mutations. Recent research shows that those who re-become ill are twice as likely to lose their lives and five times as likely to be admitted to hospital.

Measures of precaution

Vaccinations provide protection and prevention of serious disease, but protective measures such as wearing masks, letting fresh air into indoor spaces and removing stale air, avoid crowded places, are factors that reduce the possibility of contracting the virus.

Sources

theglobeandmail.com

nature.com

gavi.org

bostonglobe.com

thetoc.gr

nidirect.gov.uk