A new hyper-transmissible and possibly more deadly variant is alarming epidemiologists at a time when the world has relaxed into Covid complacency
If the fast-proliferating Omicron BA.5 sub-variant had a movie equivalent, it would be Jaws 2. The tagline: “Just when you thought it was safe to go back in the water” applies equally to the pandemic – which many believe could be resurgent due to the appearance of this highly transmissible new variant now sweeping across the US and other countries. Says the New York Times: “BA.5 and BA.4, both sub-variants of the Omicron variant that swept the world during the winter, are the most capable versions of the virus yet at evading immunity from previous infections and vaccines.”
Where did the Omicron BA.5 sub-variant originate?
The BA.4 and BA.5 sub-variants, often mentioned together, were first detected in South Africa. BA.5 was collected from a sample on 25 February in KwaZulu-Natal and quickly spread to other provinces. However, as South Africa performs more comprehensive genetic sequencing for SARS-CoV-2 samples than many other countries, there is a possibility that the BA.5 sub-variant may have emerged elsewhere and was only identified there first.
How much has BA.5 spread?
In the week preceding 25 June, it had spread to 83 countries, and represented 52% of all sequenced cases submitted, according to the WHO. As of 2 July, NBC News reported that BA.5 accounted for nearly 54% of American Covid cases, according to data from the Centers for Disease Control and Prevention. Christian Althaus, an epidemiologist at the University of Bern,believes that the decline of BA.5 will be driven by population immunity. He says that when protection lulls, the cases will increase and will drop when a certain threshold has been infected. As a result, the waves of BA.5 cases will differ from country to country. “It might be 5% in some countries and 30% in others. It all depends on their immunity profile,” Althaus says.
What makes this sub-variant especially concerning?
BA.5 alarmingly combines the high transmissibility of previous Omicron strains with the potential for severe illness characteristic of the Delta variant.
Its evasive properties are due to the mutations in spike proteins that differ from previous versions of the virus, allowing them to escape certain antibodies – increasing the probability of reinfection in both the vaccinated and unvaccinated.Specifically, unlike Delta and other Covid-19 variants, BA.5 displays around 50 total mutations, including 26 that are unique to the variant and 30 in the spike protein, the viral protein targetted by vaccines.
It’s estimated that the BA.4 and BA.5 variants are about three times less sensitive to neutralising antibodies from existing Covid vaccines compared to the Omicron BA.1 sub-variant. In early July, the FDA recommended modifying forthcoming booster shots from Pfizer and Moderna to specifically target BA.4 and BA.5, but Pfizer has said the soonest this could occur would be by October.
"At this stage, I think all these variants actually are roughly equally transmissible, so there’s not a huge difference," Francois Balloux, the director of the University College London Genetics Institute told NBC News. “It’s just some are slightly better at infecting people who have been vaccinated or infected by previous variants.”
Despite some conflicting arguements, a study published on 10 July shows that BA.5 affects the lungs far more than its predecessors and thus has similarities with the lethal Delta variant. “The ability to infect cells for BA.5 is more akin to Delta than the previous Omicron family of variants,” Dr. Eric Topol, a professor of molecular medicine at Scripps Research,writes.
Which country's healthcare systems currently under the most pressure?
Early data from South Africa does not show a large number of fatalities from BA.5 cases. The US healthcare system, however, has shown extensive hospitalizations, according to the CDC. In the US, cases were up 21% during the last week of June 2022, with deaths up 41% and hospitalisations rising by 8%. With the current rate high rate of BA.5 infections there, it is feared they could contribute to America’s second-largest wave of the Covid-19 pandemic.
“Covid-19 is very clearly not over. We’re seeing dramatic increases in the number of cases and hospitalisations in many places throughout the United States,” Jason Salemi, an associate professor of epidemiology at the University of South Florida’s College of Public Health, told the Guardian.
Waning immunity coupled with a more immune-evasive variant means that serious hospitalizations could increase. If hospitals become overwhelmed, as was the case with the Delta variant, the repercussions could be dire.
One of the biggest issues affecting the rise in US cases is its lower vaccination rate compared to other countries. Only 34% of eligible Americans – those above the age of five – have received booster doses as recommended by the CDC. In addition, Covid restrictions in the US have largely been lifted.
The eastern Mediterranean, Europe, south-east Asia and the Americas are all showing recent rises in BA.5 and corresponding deaths. Portugal – even with a higher booster rate than the US – had been particularly hard-hit: by early June, itrecorded 47 Covid deaths and almost 27,000 new cases.
Will the BA.5 sub-variant prolong the pandemic?
While the Omicron BA.5 variant is not as harmful as the Delta variant, it is highly infectious and requires a vigilant, conscientious general public to stop its spread by taking the above. However, Covid fatigue and a population unwilling to take another round of vaccines could see an increase in infection numbers, causing medical facilities to become overwhelmed and increasing the possibility of other variants emerging, potentially extending the pandemic into 2023. Limiting the long-term reach of BA. 5 will rely on countries adopting the same protocols as they have with other variants, namely mask-wearing, social distancing, ventilation, testing, and receiving the latest vaccines – but these can only work if people are on board.
Written By: Olivium staff.
Yalemedicine.org: Omicron and BA.5: A guide to what we know
New York Times: What the BA.5 subvariant could mean for the United States
CDC: Covid data tracker