According to the data by the US’s Centers for Disease Control and Prevention, subtypes BA.4 and BA.5 are driving the surge in Covid-19 cases in the US. Subtypes BA.4 and BA.5 account for 21 per cent of the cases in the country.
Since March, 2022, the World Health Organization (WHO) has been monitoring the BA.4 and BA.5, which are Variants of Interest, but Europe calls it a Variant of Concern, raising worries about it being a driver of another wave in Europe.
“BA.2 is dominant worldwide and BA.2.12.1 is dominant in the U.S., BA.4 and BA.5 are increasing around the world,” said Maria Van Kerkhove, technical lead for Covid-19 response at the WHO early this week.
WHAT ARE BA.4 AND BA.5?
These are subtypes of Omicron, the fifth variant of concern as designated by the WHO. BA.4 and BA.5 were first detected in the U.S. in late March.
CONCERNS ABOUT SURGE IN DEATHS
“BA.4 and BA.5 are on the rise in several European nations. Portugal had a major setback with BA.5 with high death rates (as high as the first Omicron wave) in spite of their older population being 100 per cent vaccinated and near 100 per cent boosted. Observations in other European countries will tell if this is a persistent trend,” Dr Rajeev Jayadevan, a keen observer of the trajectory of the virus and the vice chairman of the research cell, IMA Kerala said.
He says it is not only the virus that is rapidly changing, but also our knowledge about our immune response to vaccination and variants. “The latest paper from Imperial college published in science has revealed some startling and unexpected findings,” Jayadevan adds.
THE CURIOUS CASE OF PORTUGAL
Portugal is one of the world’s most vaccinated nations. 100 per cent of the elderly are vaccinated and almost 100 per cent have received the booster vaccine. However, Portugal’s deaths are higher in 2022 as compared to 2021 and 2020.
“96% of the whole population is vaccinated and almost 90% are boosted. Mostly, mRNA vaccines are used there and BA.5 is the variant involved. They had a large Omicron wave in January too and most deaths were in older people” says Jayadevan.
Jayadevan also said that a study from Japan states that BA.4 and BA.5 cause more lung disease in hamsters as compared to BA.2. “We do not know if that applies to humans,” he said.
The study being referred to here was published by biorxiv and says that higher lung damage and higher viral load in lungs, greater fusogenicity or ability of the virus to forcefully combine host cells was seen in hamsters.
WHAT IS DRIVING THE SURGE IN INDIA?
“India is seeing a surge mainly because Omicron sublineages are circulating, people have discarded covid appropriate behaviour and because we are now several months out of the BA.1/BA.2 wave,” says Dr Jayadevan.
Infectious Disease specialist, Dr Ishwar Gilada says that there are multiple reasons for the surge in India now. ” The current surge in Covid-19 cases globally as well as in a few pockets of India seems to be due to waning immunity – both natural immunity due to past infection or due to vaccine, it can be an immune escape as newer variants and sub-variants are known for immune escape, higher gap in the second and third dose, lack of clarity in policy for free third dose to below 60 populations, no vaccination for below 12 children and poor speed of vaccination in below 18.”
SHOULD WE ANTICIPATE A DEADLY SITUATION?
Not yet, say experts.
“BA.4, BA.5 are known to have a marginally higher replication rate (R0). However, the best thing about the current surge is it’s trajectory… Low oxygen requirements, low bed requirements/ low hospitalisation and an extremely low death rate. The case fatality rate, which is cumulatively 1.2 per cent for India and 1.87 per cent for Maharashtra, is barely below 0.1% now,” Dr Gilada says.
BA.4 and BA.5 are circulating in India but BA.1 and BA.2, which caused the third wave in India, continues to be dominant. They account for over 30 per cent of the sequences . The first case of BA.4 and BA.5 subvariants of Omicron variant of COVID-19 were first found in India on May 22, less than a month ago.
Experts say once BA.4 and BA.5 become dominant, cases will see a spike given that both these variants are much more transmissible than the otherwise MOST transmissible BA.2.
“We are much better off in India if we compare to elsewhere. US, Taiwan, North Korea, Brazil and Germany are contributing more than 50% of weekly cases globally, ” Dr Gilada said.
Health economist, Professor Rijo John is optimistic as well. “Reported daily data shows that the current uptick is already losing steam as the weekly average growth in active cases has begun to decrease. The rising weekly test positivity also seems to have slowed down. I don’t expect to see this current uptick gain much momentum in the immediate term. While caution is always advised, going by available data, I don’t see any major concern at the moment.” John says.
The The Indian Council of Medical Research (ICMR) has also been on the record to say that barring a surge in cases, it is unlikely that BA.4 and BA.5 could lead to a fourth wave in India.
“To say that the fourth wave is coming, district wise data has to be examined,” Dr Samiran Panda, Additional Director general of the ICMR told news agency, ANI
ARE VACCINES WORKING?
A South African study has shown that those who had been previously infected with Omicron but not vaccinated experienced a nearly eightfold drop in neutralizing antibodies when exposed to BA.4 and BA.5.
“Omicron evolves mutations to evade humoral immunity elicited by BA.1 infection, suggesting BA.1-derived vaccine boosters may not achieve broad-spectrum protection against new Omicron variants.” observes Dr Sanjeev Bagai, Chairman, Nephron Clinic.
Europe’s CDC also has said that BA.4 and BA.5 are less efficiently neutralised and there has been an increased rate of breakthrough infections seen in countries like Portugal.
This content was originally published here.