Omicron BA.4/5 to Become Dominant Strain Globally With More Pathogenic Than BA.2
Two new sub-variants of the SARS-CoV-2 variant strain Omicron, BA.4/5, are spreading faster than other strains in Europe and will become the dominant strain in Europe, the European CDC said on 13 June. And as they become the dominant strain, the number of hospitalisations and deaths worldwide is likely to increase.
Gaining a Foothold in Europe and the US
The European CDC warned on 13 June that the proportion of cases accounted for by BA.4/5 has reversed in Portugal, where BA.4/5 cases had reached 87% of new cases as of 9 June, with BA.5 being higher and a surge in overall cases.
Portugal, on the other hand, did not experience a spike in the overall number of cases in the last wave of the outbreak brought on by BA.2.
The European CDC said that the dominance of BA.4/5 increases suggests that they will dominate across Europe in the coming weeks and could lead to an increase in new crown cases in the coming weeks.
Data from the Office for National Statistics (ONS) shows that England and Northern Ireland have recently seen a “modest increase” in confirmed cases due to BA.4/5. This has been followed by a 10% weekly increase in hospital admissions in the UK.
Statistics from the CDC show that BA.4/5 now accounts for 21% of all cases in the US and is increasing more than BA.2.12.1, which is currently the dominant strain for the time being.
BA.4/5 was first detected in South Africa in January and February this year, and they became the leading strain in that country in May, bringing with them a new wave of outbreaks.
BA.4/5 are two sub-spectra of the evolutionary branch of Omicron. In contrast to BA.2, BA.4/5 is increasingly able to evade the body’s established immune system, allowing people who have been vaccinated or have already been infected with the COVID-19 to become re-infected.
There is no indication that BA.4/5 causes severe levels of disease or death. As of 1 June, although disease severity indicators (hospitalisations, ICU and deaths) in Portugal are lower than at the time of the last Omicron peak, they are increasing week-on-week in ringgit.
Stronger Immune Escapes
On 8 June, the leading international academic journal Cell published the results of a study by a group of scientists from the University of Oxford on the serological characteristics of BA.4/5, which showed that BA.4/5 did indeed undergo a more significant escape to sera from 3 doses of vaccine recipients.
Compared to BA.1 and BA.2, BA.4/5 showed a reduced serum neutralization rate against three doses of vaccine recipients from AstraZeneca or Pfizer. In addition, the neutralization of BA.4/5 was similarly significantly reduced using sera from people with breakthrough infection following BA.1 vaccination, suggesting the possibility of repeat infection with omicron in those already infected.
A preprint of a study by Columbia University, USA, came to a similar conclusion: the major mutation site in BA.4/5 not only made the strain more susceptible to immune escape, but by reverting to the mutation, the strain regained its adaptability, making it more susceptible to escape neutralizing antibodies and breakthrough infection.
A study conducted by Kei Sato’s team at the University of Tokyo evaluated the virological characteristics of BA.4 and BA.5 in vitro and in vivo. It showed that BA.4/BA.5 replicated more efficiently in human lung cells (respiratory epithelial cells) than BA.2. In addition, infection experiments using hamsters showed that BA.4/5 was more pathogenic than BA.2.
However, several scholars pointed out to Punch News that the above findings from in vitro and animal studies are not sufficient to conclude that BA.4/5 is more pathogenic to humans.
Dr. Yuge Wang of the National Institutes of Health (NIH) said that, taking these latest studies together, it is now certain that:
1. BA.4/5 is more amenable to humans, making it replacing other strains as the dominant strain.
2. BA.4/5 has undergone more significant escape to the serum of vaccinated individuals and is more susceptible to breakthrough infections, which will pose new challenges for future vaccination.
Several scientists have pointed out that the emergence of a mutant strain that can escape immune protection more effectively could significantly worsen the Newcastle pandemic and therefore deserves constant attention. This summer, the world will probably have to continue to live in the shadow of Omicron.
✅Product Recommendation
Genesis provides COVID-19 home-test solutions with CE self-test certified.
Post time: Jun-22-2022