The BA.5 wave: what’s this now?

BA.5, the latest subvariant of omicron coronavirus is now dominant in Belgium and the share of this variant in the total number of cases continues to rise.  Cases too are up fuelled by BA.5.

BA.5 and another subvariant BA.4 were first detected in Belgium in March.  They are believed to have originated in South Africa where they led to a rise in infections.  Today BA.5 is responsible for a majority of Belgian cases. 

Virologist Steven Van Gucht says the emergence of new (sub)variants often leads to surges in infections and this is what we are witnessing now. Above all infections are up.  The number of hospitalisations too is edging higher, but there’s been no big rise in numbers in critical care the virologist notes.

Biostatistician Geert Molenberghs adds BA.5 isn’t more catchy, but it is more effective at sidestepping the immunity built up in the population. People are getting reinfected after only two months but the immunity that has been built up means patients aren’t that sick.

Molenberghs says the whole omicron family makes people quite ill.  Let loose on a population without any or low immunity – what happened in Hong Kong in March – would mean high hospitalisations and deaths.

“BA.5 displays delta variant symptoms and goes further into the lungs than other omicron subvariants, but the immunity we have built up makes us less unwell” says the biostatistician.

Prof Van Gucht expects more patients to end up in critical care but is confident the health care service can cope. Portugal experienced a similar wave.  Hospitalisations doubled, but the impact on critical care was more limited.

Steven Van Gucht: “It’s important to realise the virus hasn’t disappeared.  You can still get ill or very ill.  Risk groups should take care.  An FFP2 mask on public transport is a sensible measure”.

Biostatistician Tom Wenseleers (KU Leuven) expects a wave smaller than the original omicron wave, but larger than the BA.2 wave in March when 10,000 people a day were infected and there were over 200 hospitalisations a day.

Vaccinologist Pierre Van Damme (UAntwerpen) says vaccines are providing less protection against new variants.  New adapted vaccines are being developed.  Regulatory bodies are expected to provide guidance this summer.  Meanwhile people who haven’t had their first booster shouldn’t delay.  Over 80s and risk groups would do well to go for a second booster.  

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