A range of new Covid-19 subvariants are currently circulating overseas, and some have already reached our shores.
With summer around the corner, the SMC asked experts to comment on what the Covid-19 landscape is looking like right now
in other countries, and how it might affect Aotearoa New Zealand.
Dr Joep de Ligt, Lead Bioinformatics & Genomics, ESR, comments:
“It is clear that the next wave of COVID-19 is building in the Northern Hemisphere, with hospitalisations rising
rapidly. Countries like Austria surpassed their previous wave within a matter of weeks and several others are not far
behind.Figure 1. Source: Our World in Data. Hospitalised cases per million over a half year period. CC BY 4.0
“What is also becoming clearer is that these waves are driven by a variety of new variants, most of them descendants
from our previous waves. Because these waves were not met by strong public health action they have been given the
opportunity to spread and evolve into these new forms.
“As Eric Topol highlights in this thread, these variants share common mutations, called convergent evolution. These mutations seem to convey immune evasive
properties meaning that immunity from previous infections and vaccines offer less protection as well as that monoclonal
antibody treatments will be less effective. This has led to increased calls for boosters and the new bi-valent vaccine
to be rolled out widely and quickly to help prevent health systems from being overwhelmed and keep people safe.
“One particular variant BQ.1.1 is being monitored due its competitive advantage over the ancestral BA.5 with estimates around 12-14%, putting it ahead
of BA.2 and BA.5 advantage over their predecessors, for which New Zealand saw rapid replacements.”
No conflicts of interest declared.
Professor Michael Plank, Te Pūnaha Matatini and University of Canterbury, comments:
“Many Northern Hemisphere countries are currently in a Covid wave that looks like it’s being caused by a combination of
waning immunity, changing seasons, and new variants spreading. The variant situation is more complicated than in
previous Omicron waves, which have each been dominated a single subvariant – first BA.1, then BA.2 and most recently
BA.5. This time, there is a variant soup consisting of several different lineages that appear to be outcompeting BA.5.
“Some of these subvariants are already spreading in New Zealand and it’s likely they will trigger a wave here as well.
The size of the wave is highly uncertain – it could be on a par with the BA.5 wave we had in July. It could be smaller
as we move towards summer and people spend more time outdoors, making it harder for the virus to spread. Or it could be
more prolonged if some of faster-growing lineages take hold.
“We have reached a stage of the pandemic where waves of Covid-19 occur in a cycle. These waves recede when enough
immunity has built up from a combination of vaccination and prior infection. But over time that immunity wanes and the
virus evolves to bypass it, allowing the cycle to start again. This is an inevitable cycle in a respiratory pathogen
that is becoming endemic. Our best tools to mitigate it are vaccines and treatments that reduce the risk of severe
illness. Many countries including Australia are now deploying updated Omicron vaccines to strengthen and broaden
immunity, particularly in high-risk groups.”
Conflict of interest statement: “Michael Plank is funded by the Department of Prime Minister and Cabinet for
mathematical modelling of Covid-19.”