A former World Health Organisation (WHO) official has claimed that the BA.2 subvariant of Omicron has a basic reproduction number (R0) of around 12 (each infected person passes it on to 12 others), making it as infectious as measles, the most contagious disease known, and nearly six times as infectious than the original Wuhan strain (with an R0 of 2.5). Here’s the report in MailOnline.
Professor Adrian Esterman, a leading epidemiologist in Australia, said BA.2 is 40% more transmissible than the original variant.
He claimed it would have a basic reproduction number (R0) of around 12, meaning if left to spread unchecked every infected person would pass it to a dozen others.
It would make the sub-strain five times more infectious than the original Wuhan virus and one of the most contagious diseases known to science.
The claim would explain why the mutant virus was able to outstrip its parent strain in the U.K. in about a month and undermine China’s Zero Covid policy, which has until now managed to suppress every version of the virus.
Explaining his methodology, Professor Esterman said: “The basic reproduction number (R0) for BA.1 is about 8.2, making R0 for BA.2 about 12. This makes it pretty close to measles, the most contagious disease we know about.”
The R0 number is the average number of people each BA.2 patient would infect, if there was no immunity in a population or behavioural changes.
But most scientists say there is no reason to be concerned over the variant because it is just as mild as the original Omicron.
The BA.2 subvariant is now behind almost every case in England, or 83% of infections last week, according to official estimates.
It became dominant three weeks beforehand, accounting for 52% of all infections in the week to February 20th.
The Office for National Statistics (ONS) estimates cases have been rising since mid-February, with one in 25 people in England estimated to have been infected last week.
Hospitalisations are also creeping up, but the majority appear to be incidental – when someone tests positive after admission for another illness.