Using mathematical modelling to determine of the spread of Covid-19 is very difficult to do accurately due to the cluster nature of the infection
Comment: Covid-19 is a cluster infection and so does not follow the typical pattern in the population of the usual infections such as influenza or measles. Trying to equate Covid with seasonal influenza is fraught.
As a cluster epidemic, Covid spreads in the population from group-to-group rather than person-to-person. However, once in a group it spreads more easily from person-to-person because of the closeness and frequency of contact among its members.
Therefore, the number of people infected each day depends on the number of infected groups and their size, and can be expected to fluctuate considerably.
The clustering nature and resulting dynamics of the infection, combined with the lack of information about groups within the population and how they interact, makes the production of accurate mathematical models of the infection very difficult.
As restrictions on the movement and the mingling of people decrease, the number of groups infected very rapidly increases in cluster epidemics, as we have seen in the latest outbreak.
Covid occurs as a series of ongoing eruptions of infection within previously uninfected groups of various sizes. The eruption of infection in the group resolves when the infection cannot find someone else to infect within that group.
The total number of new cases in the population is determined by the number and size of the eruptions. In almost all countries there have been repeated multiple eruptions of infection in the population, about every four months on average, throughout the pandemic.
The size and duration of the eruptions of infection, like the Delta and Omicron outbreaks, are difficult to predict. The repetitive eruptions of infection mean there is no real flattening of the curve, just a lull until the next eruption.
When an eruption has almost died out, one of the many ongoing changes to the virus tends to predominate creating a new worrisome variant but it is hoped that further eruptions will become less common and involve milder variants of the disease.
Vaccination tends to have a limited effect on the spread of infection between groups, unless everyone in a group is vaccinated. However, even some who are vaccinated can still become infected so large groups tend to remain susceptible.
Therefore, the spread in the population can be difficult to contain by vaccination alone, especially as the size of population groups increase as restrictions are lifted. Some restrictions can be expected to remain necessary for the control of Covid.
The Government, acting on advice, has been seeking to allow Covid to become a common flu-like illness within the population but with hopefully only a minor risk of serious illness.
However, as a very large number of people will become infected, there may be many fatalities simply because of the large number of people infected, even with the occurrence of milder variants such as Omicron or milder disease in those vaccinated.
Throughout the year many people newly develop various diseases. That is, very susceptible people are continually being added to the population and the continuing circulation of Covid can be expected to be a considerable danger to them.
The pandemic has had a major effect on the long-term viability of many businesses. Having been a world leader in the control of serious Covid infection, we have chosen to follow other countries and let it run its course which may not have an ending in the immediate future.
This is likely to change the mixture of businesses and institutions who, as their workforce become infected, suffer economically. This will particularly affect those that require a large workforce with considerable client interaction.
