Why has there been a fourth wave?

The new ‘Omicron’ variant of COVID19, was first detected in South Africa and reported to the World Health Organisation (WHO) on the 24th of November. Omicron has many new mutations that make it more transmissible and also capable of evading the immunity gained from previous variants. This has increased the number of cases in Africa and throughout the world.

How serious is the fourth wave?

Thankfully, two main factors have meant the Omicron wave in Africa was less serious than it could have been. Firstly, immunity gained from vaccination and previous infection is still effective at preventing severe disease and death. Secondly, there is evidence that the Omicron variant itself causes less serious illness than previous variants like Alpha and Delta.

Why is the wave declining?

The Omicron wave in Africa has started to decline because, one person on average, now infects less than one person. The number of people a person infects on average is called the ‘R number’. When the R number is greater than one, the number of cases increase, but when the R number is less than one, cases decline. Few people are now becoming infected because of behavioural changes. Examples of this include government-mandated restrictions like curfews and wearing face masks. However, people might also look to make voluntary changes in their behaviour, like choosing to meet in smaller groups outside. Additionally, as more people eventually become infected by the Omicron variant and recover, they remove themselves as potential targets for infection again, helping to bring down the R number.

Where is Africa at now with the Omicron wave?

The good news is that cases and deaths are now both falling. It is normal to see deaths lag and decline at a lower rate than cases. This is because as well as being complicated to record, it takes time for an infection to develop into a problem serious enough to be fatal.

Where do we go from here?

Although Omicron cases are now falling, we should still expect new variants to appear that have some kind of advantage over previous ones. How well this new variant spreads is largely dependent on how transmissible it is and how good at evading immunity it is. Although Omicron was less severe than prior variants, like Alpha and Delta, new variants could be more or less deadly. However, as scientists continue to learn more about the virus, the situation is improving.

For instance, preventative measures, treatments, and vaccines, will all tend towards working with greater efficacy over time.


Sam Mark


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