Kenya flattens Omicron wave

Kenya has flattened the fifth Covid-19 curve caused by the Omicron variant, but experts have warned against lowering the guard.

In the past couple of weeks, the country’s positivity rate has been below 5 per cent, while the highest ever recorded being 3.7 per cent. In the last three days, the average positivity rate was 1.6 per cent. The average positivity rate in the last 14 days is 2.4 per cent.

The World Health Organization’s (WHO) threshold for a flattened curve is a positivity rate of less than 5 per cent for two weeks.

“The five waves in the last two years of the pandemic show a seasonal pattern that closely matches the circulation peaks previously documented in Kenya for flu and the other influenza-like respiratory viral illnesses,” said Dr Ahmed Kalebi, a consultant pathologist.

When the positivity rate is high, he said, it is likely influenced by combinations of low temperatures and low humidity just as other studies have shown in other respiratory illnesses like influenza.

“We have already flattened the curve with more than two weeks of the positivity rate being below 5 per cent. Remember it isn’t just about the change in temperature, change in humidity also affects seasonal airborne viral transmission,” he said.

New variants

Dr Shem Otoi, a mathematician who does predictive models of Covid-19, has observed the seasonality of the waves and predicts a sixth one in May.

“Our model says every wave is associated with new variants. These mutations could last for about six months before becoming a new variant. The waves capture the cyclic nature of socio-environmental factors like the weather as well as other periodic human activities,” he said.

Compared to Delta, Omicron had a steep rise in infections, resulting in the country’s highest ever positivity rate. But it dropped just as fast.

“The Omicron variant infected so many people so fast within a matter of a few weeks. I reckon more than 80 per cent of the population was exposed to Omicron. This means that after a month, it reached the saturation point as there were not many people left to infect,” said Dr Otoi.

Positivity rate

Dr Kalebi said the rapid fall in the positivity rate for the Omicron-driven wave and case load was due to its pathogenicity – the capacity to cause severe disease.

“The lethality of a virus affects hospitalisation and fatality rate.  For Omicron, the hospital admissions were much lower, about half of the previous waves, despite a high case load. ICU admissions was at about a quarter of the previous waves and deaths were about a fifth,” he added.

With the flattened curve, the experts said the containment measures in place should be upheld.

“Provided that our vaccination rate remains less than 70 per cent, we will continue to have future waves. We need to observe the public health protocols that have been set up by the Ministry of Health. We have succeeded in this wave because, we have strengthened our health systems, so we should not relax,” Dr Kalebi said.