If you’ve struggled to keep track of the latest coronavirus variants circulating around the world, you’re not alone.
Two years since the start of the COVID-19 pandemic, we’ve heard of the Alpha, Beta, Gamma, Delta and Omicron variants, but a new one named after a Greek letter hasn’t emerged so far this year.
Instead, a string of “sublineages” - or subvariants - of Omicron popped up. They basically feature different mutations in the spike protein that allows the virus to infect cells.
Unfortunately for our tired brains, those naming these new subvariants seem to have lost inspiration and we now face an alphabet soup of letters and numbers: BA.1, BA.2, BA.3, BA.4 and BA.5.
Sexy, right? But wait; there are also recombinant forms mixing several subvariants of Omicron, such as XE which is a mix of BA.1 and BA.2.
So, what do you really need to know about these subvariants? We deciphered the letters and numbers to make sense of them for you.
Variants keep coming - and they’re getting more contagious
The World Health Organization (WHO) says it’s keeping close tabs on all the variations of SARS-CoV-2 - the original virus causing COVID-19 - and expects more will surface in the future.
That’s because the virus “is circulating at such an intense level,” Maria Van Kerkhove, the infectious disease epidemiologist who serves as technical lead for the WHO’s COVID-19 response, told reporters on May 10.
“What we can say is as this virus evolves, the latest variants that we have, the Omicron variants and all the sublineages are more transmissible than the last variant that is circulating, and we know that that will continue,” she said.
Worldwide, the predominant Omicron subvariant right now is BA.2. And that subvariant is spreading faster than BA.1 did.
BA.4 and BA.5: 'Variants of concern'
Even more transmissible than BA.1, BA.2, or the less-talked-about BA.3, are the subvariants BA.4 and BA.5.
Just bear in mind that so far in this series, the higher the number, the more contagious the subvariant.
BA.4 and BA.5 were first detected in South Africa in January and February 2022 respectively, and since then they have become the dominant variants there.
The European Centre for Disease Prevention and Control (ECDC) has now classified both BA.4 and BA.5 as "variants of concern" due to their rapid spread, particularly in Portugal.
As of May 8, the Portuguese National Institute of Health estimated that BA.5 accounted for around 37 per cent of positive COVID-19 cases and that its daily growth rate of 13 per cent would make it the dominant variant in the country within just two weeks, by May 22.
An Omicron subvariant doesn’t protect you from the next
You may have already been comparing with your friends which COVID-19 strain and subvariant you’ve caught so far. Get ready for more of that, as we’re really not done with COVID-19 any time soon.
The ECDC says BA.4 and BA.5 “could cause a significant overall increase in COVID-19 cases in the EU/EEA in the coming weeks and months” and will soon become the dominant variants in the region.
"The currently observed growth advantage for BA.4 and BA.5 is likely due to their ability to evade immune protection induced by prior infection and/or vaccination, particularly if this has waned over time," the agency said in a statement on May 12.
It said limited data from in vitro studies looking at the blood of unvaccinated individuals previously infected with BA.1 suggest that both BA.4 and BA.5 are capable of escaping the immune protection induced by that prior BA.1 infection.
COVID vaccines do make a difference against variants
The serum of vaccinated people performed better in the Petri dish when attacked by BA.4 or BA.5, but "protection derived from currently available vaccines does wane over time against the Omicron variant," the ECDC said.
Hence the boosters we’ve been getting.
From what we know so far, vaccines remain highly effective against the worst outcomes, WHO stresses.
"The vaccines are holding up very well against severe disease and death, so it is absolutely critical that people get vaccinated," Van Kerkhove said.
The WHO has set a target of vaccines reaching 70 per cent of all people across all countries by June, and is especially concerned about vaccinating all health workers and frontline workers as well as people over 60 or with underlying conditions, as they are more vulnerable to serious cases of COVID-19.
Are BA.4 and BA.5 more dangerous?
While both Omicron subvariants are more contagious than previous ones, there is currently no indication they are more severe, and the WHO says studies on the topic are underway.
It says it’s seeing an increase in COVID-19 hospitalisations in South Africa, "but that can be expected when there’s an increase in cases," according to a spokesperson.
The ECDC has a similar assessment.
"Based on the limited data currently available, no significant increase in infection severity compared to the circulating lineages BA.1 and BA.2 is expected," it said.
"However, as in previous waves, if COVID-19 case numbers increase substantially, some level of increased hospital and ICU admissions is likely to follow".
Keeping 'eyes and ears' on the virus
Both agencies are calling on national health authorities to remain vigilant and to continue testing populations and carrying out genome sequencing of samples, to keep tracking the spread of variants and how they might influence hospital admissions.
BA.4 and BA.5 have been reported in about 15 countries so far but only a few hundred sequences of each are available globally, the WHO said.
"Our ability to detect this is being substantially hindered because testing rates have plummeted and, in doing so, our sequencing rates have plummeted as well," Van Kerkhove said.
"It is really important that surveillance for this virus continues, that testing remains strong, that sequencing is intelligent, and that we have good geographic representation so that we have good eyes and ears on the virus".