BA.4 and BA.5 lineages - symptoms, immune escape

GARDEN ROUTE | KAROO NEWS - The NICD explains that the BA.4 and BA.5 lineages are currently still classified as the Omicron variant, meaning that they are not a new Variant of Concern (VOC); rather, they are Omicron viruses with a new combination of mutations.

In terms of their mutations, BA.4 and BA.5 share mutations across their genomes with both BA.1 and BA.2 (also lineages of Omicron), but are most similar to BA.2.

BA.4 and BA.5 differ from one another in mutations that are outside of the spike gene but they are identical to each other in terms of spike mutations. For this reason, they are often discussed together.

Possible immune escape

The NICD says as the BA.4 and BA.5 lineages have some different mutations to other Omicron lineages it is possible that there may be some immune escape leading to an increase in the number of COVID-19 cases.

However, South Africa has a high immunity due to previous infection and vaccination, which has been shown to protect against the risk of developing severe COVID-19 disease. There is currently no indication that this will change with BA.4/BA.5, however the situation will continue to be monitored closely.

First cases

According to the NICD, the Omicron lineage BA.4 was first detected from a specimen collected on 10 January 2022 in Limpopo. As of 29 April 2022, BA.4 has been detected in all provinces. The percentage of sequences designated BA.4 has grown from <1% in January 2022 to > 35% in April 2022.

The BA.5 lineage was first detected from a specimen collected on 25 February 2022 in KwaZulu-Natal. As of 22 April 2022, BA.5 has been detected in Gauteng, Limpopo, Mpumalanga, KwaZulu-Natal, the North West, and the Western Cape.

The percentage of sequences designated BA.5 has increased from <1% in January 2022 to 20% in April 2022 (3).

More than 50% of sequences BA.4 and BA.5

Collectively, the percentage of sequences assigned to BA.4 and BA.5 have increased from <1% in January 2022 to >50% in April 2022.

Both lineages have been detected in countries outside South Africa, such as the USA, UK, and Botswana. These lineages are being closely monitored and data are being uploaded regularly.

Symptoms with BA.4/BA.5

As of 29 April 2022, there are currently a relatively small number of BA.4 and BA.5 cases and so it is too early to definitively know if there are any new symptoms associated with these lineages. However, given that the lineages are still classified as Omicron, and that the majority of mutations (particularly within the spike protein) are the same, it is likely that symptoms will be similar.