What does the end of a pandemic look like? What’s next? The UK Scientific Advisory Group for Emergencies (SAGE) has published four possible scenarios that could unfold in the next 12-18 months.
The experts classified the scenarios as ‘reasonable best case’, ‘central optimistic’, ‘central pessimistic’ and ‘worst case’. None of them rule out the possibility of new variants. The core assumption is that you haven’t got a steady state, meaning the coronavirus keeps coming in waves regardless of scenario.
Scenario 1: Reasonable Best-Case
Further variants emerge but don’t differ hugely from the variants to date in terms of how infectious or severe it is. The assumption in this scenario is that there’s minimal vaccine and immune escape from where things stand now. In this scenario there will be minor seasonal and regional outbreaks from waning immunity and small genetic (antigenic) changes. The existing vaccines in this scenario will be used annually to boost the vulnerable only. Antivirals will have a significant impact on deaths and illness, and remain effective. Years with higher SARS-CoV-2 waves will tend to have fewer influenza cases.
In the next 12-18 months: Relatively small resurgence in Winter/Autumn with low levels of severe disease.
The experts believe that this is the most likely scenario.
Scenario 2: Central Optimistic
This scenario assumes there will be increasing global levels of immunity which will soften the severity of the virus. There will be waves of infection though because of waning immunity and/or the emergence of new variants. The general pattern will be of annual seasonal infection with good and bad years. Bad years will be due to variants with both high transmissibility and severity. Severe illness and the risk of death will largely be limited to vulnerable people, the elderly and those without past infection or vaccination. Vaccines will be regularly updated and given annually to the vulnerable and to others in bad years. The community will respond well to outbreaks and be willing to take on protective behaviours at high levels. Some countries will mandate for this e.g. with masks during bad years. Anti-viral resistance begins to appear and will limit their use until combination therapies become available.
In the next 12-18 months: The scenario predicts seasonal waves of infections in Winter/Autumn with comparable size and severity to the current Omicron wave.
The experts believe that this scenario is a little less likely and depends on global immunity going up and even though the severity of the virus might rise a little or stay the same, its net effect will be less.
There will be annual vaccines for vulnerable people, and the population takes precautions like wearing masks, social distancing, and so on
Scenario 3: Central Pessimistic
This scenario assumes there will be a lot of virus circulating and that will generate the emergence of unpredictable new variants for many years to come – often more than once per year – with immune evasion and similar average severity to the delta variant. Even so, existing immunity and updated vaccines will continue to provide good protection against severe disease. These repeated waves of infection may cause widespread disruption with impacts on groups such as children in education. The scenario assumes annual vaccination with updated vaccines and widespread anti-viral resistance. Influenza rates don’t fall and overlapping SARS-CoV-2 waves create health system stress. The community is not good at changing their behaviour which leads to more stringent mandates in some countries.
In the next 12-18 months: New variants of concern produce large waves of infections, potentially at short notice and not necessarily in Winter/Autumn. Severe disease is concentrated in the unvaccinated, vulnerable and elderly.
The good news in this scenario is that updated vaccines continue to provide good protection against the most severe outbreaks.
Scenario 4: Reasonable Worst-Case
This is the nightmare scenario, with high levels of virus circulating, so much so that it gets back into animals, picks up some nasty genes and re-emerges as a more transmissible, deadly version. Annual vaccination with constantly updated vaccines will be needed and communities resist changing their behaviour, at a time when it’s needed most. There’s also widespread anti-viral medication resistance and testing technologies may fail.
In the next 12-18 months: This scenario leads to a very large wave of infections with increased levels of severe disease seen across a broad range of the population, although the most severe health outcomes continue to be felt primarily among those with no prior immunity.
What’s the takeaway for Australia?
We’ve really got to be sensitive to the fact that we can’t rely on vaccines and drugs moving forward. We’ve got to be prepared to move in and out of mask wearing; social distancing and taking care. We are unlikely to go back to lockdowns, but we’ve just got to be prepared to protect ourselves and protect others moving forward because we will come to gaps in vaccine and drug coverage which we’ve got to transition across by public health measures.
This pandemic is not over yet. TheWorld Health Organisation Director-General Tedros Adhanom Ghebreyesus said at an executive board meeting on January 24 2022. “It is still dangerous to assume that omicron will be the last variant, or that we are in the endgame of the pandemic.”
