The discovery of the new BA.2 Omicron variant has raised concerns that South Africa could see another wave in infections – but scientists say the subvariant is unlikely to be a ‘gamechanger’ and require additional interventions.
There are three officially designated subtypes of Omicron: BA.1, BA.2 and BA.3 — with the BA.2 sub-variant quickly spreading in South Africa. BA.2 possesses up to 27 mutations that are not found in the original version of Omicron BA.1.
Research published this week shows that these mutations make BA.2 between 30-34% more infectious than BA.1, and mild cases of the latter may not offer much protection against future infections.
This has led to concerns that BA.2 could cause a second surge of infections in the current wave in the country.
However, Richard Lessells, an infectious diseases physician at the University of KwaZulu-Natal in Durban, says the subvariant is unlikely to cause ‘a huge wave of reinfection’ in South Africa.
Speaking to the Financial Times, Lessells said that although an increase in infections could be seen, it was unlikely to require additional responses.
“We might expect that there would be some reinfections because in many cases the immune response to Omicron may not be a particularly strong one,” said Lessells. “But I think it’s very unlikely that it’s going to break through the immunity from BA.1. It’s definitely not a game-changer.”
This was echoed by Ravi Gupta, professor of clinical microbiology at Cambridge University, who said despite BA.2’s transmission advantage, it doesn’t warrant public health measures over and above what governments have put in place in response to the original Omicron.
“BA.2 may be more transmissible by a certain margin but Omicron is already so transmissible – the incremental increase is unlikely to throw us off course,” he said.
South Africa’s excess deaths, seen as a more accurate assessment of the impact of the coronavirus than official statistics, have also fallen to levels last seen before the omicron variant was identified, Bloomberg reported.
The number of excess deaths, a measure of mortality over a historical average, fell to 886 in the week ended 23 January, compared with 1,329 the week earlier, according to the South African Medical Research Council.
That’s the lowest since the week ended 24 October when there were 824 excess deaths. The first omicron cases in South Africa were identified from samples taken in early November.
The fall in mortality adds to evidence that the variant, while more transmissible than earlier strains, causes milder disease. The seven-day average of confirmed cases in the week ended 20 January was 3,723, compared with 506 in the week ended 21 October, according to government statistics.