Omicron sub-lineages likely can evade immunity: S. Africa scientist

JOHANNESBURG • New Omicron sub-lineages, discovered by South African scientists this month, are likely able to evade vaccines and natural immunity from prior infections, the head of gene sequencing units that produced a study on the strains said.

The BA.4 and BA.5 sub-lineages appear to be more infectious than the earlier BA.2 lineage, which itself is more infectious than the original Omicron variant, Professor Tulio de Oliveira, the head of the institutes, said.

With almost all South Africans either having been vaccinated against the coronavirus or having had a prior infection, the current surge in cases means that the strains are more likely to be capable of evading the body's defences, rather than simply being more transmissible, Prof de Oliveira said.

There are "mutations in the lineages that allow the virus to evade immunity", he said in a response to queries.

"We expect that it can cause re-infections and it can break through some vaccines, because that's the only way something can grow in South Africa where we estimate that more than 90 per cent of the population have a level of immune protection."

South Africa is seen as a key harbinger of how the Omicron variant and its sub-lineages are likely to play out in the rest of the world.

South African and Botswanan scientists discovered Omicron last November and South Africa was the first country to experience a major surge of infections as a result of the variant.

The new sub-lineages account for about 70 per cent of new coronavirus cases in South Africa, Prof de Oliveira said in a series of Twitter postings.

South Africa recorded 4,146 new cases, with a test positivity rate of 18.3 per cent, on Thursday. That compares with 581 cases and a positivity rate of 4.5 per cent on March 28.

Public health specialist Waasila Jassat of the National Institute of Communicable Diseases said during a conference call yesterday that hospitalisations are rising but there has yet to be a significant rise in deaths.

The sub-lineages have been detected in seven of South Africa's nine provinces and 20 countries worldwide.

BLOOMBERG