Explained: Can Omicron subvariants give you Covid more than once?

Can a person who has had a previous omicron infection get it again?

“Yes, people who have had an Omicron infection in January may get another infection once other sub-variants such as BA.4 and BA.5 start circulating in the community. We have seen these variants take over from BA.2 to become the dominant variant in other countries. They are about 13 per cent to 15 per cent more transmissible than BA.2 which in itself was several-fold more transmissible than the wild type of the virus,” said Dr Lalit Kant, former head of the department of epidemiology and infectious diseases at the Indian Council of Medical Research.

Similarly, BA.2.12.1 that was first detected in New York is thought to be about 27 per cent more transmissible.

He added, “Not only that, the immunity from Omicron infections in January – which did not cause severe disease and hence would have led to fewer antibodies developing – must have started going down. Immunity from vaccination also starts waning after five to six months. So, there can be an increase in infections.”

Are these new variants likely to become dominant in India?

The first cases of BA.4 and BA.5 were detected in January and February in South Africa and became the dominant variants by May, suggesting a clear transmission advantage over the previous BA.2. Similarly, BA.5 has already become the dominant variant in Portugal.

Although proportions of the two variants are less in other European countries, the European Centres for Disease Control and Prevetion says, “The growth advantage reported for BA.4 and BA.5 suggests that these variants will become dominant throughout the EU/EEA, probably resulting in an increase in Covid-19 cases in coming weeks.”

Other than its transmission edge, these variants can also circumvent some of the immunity gained from previous omicron infection or vaccination.

Data from lab studies has shown that BA.4 and BA.5 are more distant from their cousins BA.1 and BA.2 that led to the January surge in India. What this means is that vaccines that use spikes from the ancestral virus would be less effective.

“BA.4 and BA.5 are less efficiently neutralised by sera from individuals vaccinated with three doses of Covid-19 vaccine (AstraZeneca or Pfizer) or by sera from BA.1 vaccine breakthrough infections. In addition, there has been an increased rate of re-infection in Portugal,” the European CDC said.

So, could there be a wave with these new variants?

Dr Kant explained, “If we go by the example of other countries – and anything about Covid-19 has been notoriously hard to predict – it is likely that there will be some increase in infections but the cases are likely to be milder, leading to fewer hospitalisations and deaths.”