The severity of the third wave of the Covid-19 pandemic will depend on whether it arrives in May or July/August, says Covid-19 Working Group of the Actuarial Society of South Africa (Assa) member Adam Lowe.
Lowe says the data indicates that the third wave will follow the pattern of the so-called Spanish Flu pandemic of 1918 and 1919, which saw the quick arrival of a third wave after the second wave.
If this pattern is emulated, the third wave is likely to be less severe than the second.
From the three scenarios foreseen, an early third wave in May is, however, the most likely, given the public holidays and school holidays in April.
Lowe explains that while SA’s first wave was more severe than the relatively low peak of the Spanish Flu first wave, the pattern of these waves was very similar, in that after smaller first waves, there was roughly a four-month gap and then large second waves.
SA experienced the peak of the first wave of infections between July and August 2020 and the peak of the more severe second wave from December 2020 to January 2021.
The Covid-19 wave patterns studied by the Assa Covid-19 Working Group show they are similar to those of the Spanish Flu pandemic, this is despite that flu being spread by the H1N1 virus and not a coronavirus.
The graph below shows weekly deaths from the H1N1 virus in the UK from June 1918 to May 1919. The article from which the graph was extracted noted that the global wave pattern of the Spanish Flu was similar to that of the UK.
The working group says there is a second scenario, which will see the third wave have a similar magnitude to the second wave. The longer the peak is delayed, the more likely this scenario will play out.
Lowe says since the early, less severe third wave theory is based on the build-up of some level of immunity in the population following the first and second waves, for a third wave to have a similar magnitude to the second, it would require the virus to overcome these immunity levels in some way.
This could happen if the virus mutates into a new variant that is even more infectious than the 501Y.V2 variant.
Another way is if enough time passes for the immunity granted to those infected runs out or reduces sufficiently to allow for significant levels of reinfection to occur.
Worst scenario – Armageddon
Worst case scenario is the working group got its model wrong and the third wave does not follow any of these patterns.
Lowe says the worst-case scenario would be an early third wave in May that is as severe or even more severe than the second wave.
For this to happen, a combination of circumstances would be required to create an environment where an even more infectious variant runs through a population with lower than anticipated immunity.
This could happen if there was an overestimate of the people infected in the first two waves, which would result in a flawed estimate of immunity.
Or if there was a series of superspreader events either through natural behaviour over the holiday period or reduced vigilance on the part of a population that has been locked down for over a year.
The more rapid than expected emergence of a new and more deadly variant of the virus could also lead to this scenario.
He says that for this to materialise an unlikely, but not impossible, combination of circumstances would be required.
This story first appeared on Moneyweb and has been republished with permission.