Dr Muiris Houston: Omicron may push Delta out for good

Could we really be entering our third year of uncertainty with Covid-19? A successful vaccine programme (at least in this part of the world) has made a difference, but we remain firmly in pandemic mode. So is Sars-CoV-2 fated to become our ‘groundhog’ virus?

Unprecedented change overwhelmed us in 2020 and 2021. Enduring the Covid pandemic has meant living through drastic adjustments to social and workplace environments, a restriction of movement and choice, and prolonged bouts of social distancing and isolation. Skewing lives socially, professionally and financially, adapting to Covid has ground many of us down.

The ongoing uncertainty has us desperately wanting a new normal. A life where the risk of Covid-19 remains, but can be boxed away as an annual infectious disease threat. Perhaps the most frequent question I am asked is: when will Sars-CoV-2 morph into the flu?

Renowned infectious disease expert Dr Anthony Fauci says he does not see the threat of Covid-19 remaining as it is. "Even with viruses that mutate and change, you reach a steady state where there's enough infection and/or vaccination in the community that there is enough background immunity that the level of infection is both less in quantity and severity of disease."

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How things play out in the immediate future largely depends on three factors: the novel coronavirus’s ability to infect a huge number of people (its transmissibility); its potential to fuel waves of severe cases and deaths (its severity); and its ability to evade immunity (whether obtained by vaccination or prior infection).

A number of questions concerning the Omicron variant remain. Will Omicron – which already accounts for the majority of cases – take over completely, or will Delta keep a toehold? A recent South African study found that an Omicron infection protects against future Delta infections, suggesting that the newer variant might be able to push Delta out for good.

On the severity issue, emerging scientific studies suggest that the Omicron variant, which excels at infecting cells in the upper respiratory tract, struggles to target cells deeper in the lungs. The research supports the idea that Omicron is intrinsically less likely to cause severe disease than other variants.

The longer inequity continues, the higher the risks of this virus evolving in ways we can't prevent or predict. If we end inequity, we end the pandemic

How long will Omicron stay with us? Statistics from South Africa point to a massive wave of community infection followed by a rapid decline in numbers. Data emerging from several European countries also suggest that the Omicron wave may be a short, sharp shock compared to the prolonged waves of infection that went before.

Modelling the pandemic future is a somewhat rocky science, as we have become all too aware in Ireland. For what it's worth, researchers from the University of Washington predict a quieting down of Covid-19 for much of 2022. Because Omicron is going to infect 40 per cent of the world population in the next two months, it will raise population-wide immunity for a while, they say. After the significant Omicron wave passes through, transmission should drop to very low levels. And ongoing rollouts of vaccines should help keep it that way.

The WHO’s director-general Tedros Adhanom Ghebreyesus is optimistic and says “while no country is out of the woods from the pandemic, we have many new tools to prevent and treat Covid-19. The longer inequity continues, the higher the risks of this virus evolving in ways we can’t prevent or predict. If we end inequity, we end the pandemic”.

My own prediction? If Omicron turns out to be the last Sars-CoV-2 variant of concern, then we are likely to enter an endemic phase of infection some time this year, bringing with it fewer deaths. Annual vaccination and anti-viral treatments will facilitate a “new normal”.

But if future variants of concern emerge then I’m afraid all bets are off. Uncertainty will prevail, and we will continue to experience the considerable social challenges of adopting to an ongoing global pandemic.

mhouston@irishtimes.com