Younger age groups dominated infections during initial cluster of Omicron – study

A HEALTH worker tests a man for Covid-19 in Alexandra in Gauteng. | Reuters

A HEALTH worker tests a man for Covid-19 in Alexandra in Gauteng. | Reuters

Published Dec 22, 2021

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A SOUTH African-Russian scientific study found that younger age groups played a significant role during the initial stage of the spread of the Omicron variant in the country and that the densely populated Tshwane district was the initial cluster of transmission.

The Department of Health revealed in a press release on Wednesday that the study or “mission” was organised in accordance with the agreement between the presidents of Russia and South Africa.

The mission analysed data on the epidemiological characteristics of the new genetic variant and the features of its distribution in the country.

Leading South African scientists collaborated with 20 scientists and experts of Rospotrebnadzor and the Ministry of Health of Russia from December 13 to 22.

The study found there was a high incidence of Omicron infection in younger patients, especially in children in the initial stages.

Head of the division of public health, surveillance and response at the National Institute of Communicable Diseases (NICD), Dr Michelle Groom, said during a media briefing that the beginning of the fourth wave saw a rapid increase of infection in the younger age groups.

“We saw that the fourth wave started in the younger population initially but it has now moved into the other age groups. The waves started in Gauteng, particularly at the learning institutions,” she said.

Weekly case incident by age group. Graphic NICD

While Gauteng was the initial hot spot in the country, the majority of new cases are now from KwaZulu-Natal.

On Tuesday the NICD reported 26% of new cases were from KwaZulu-Natal, followed by Western Cape with 22%, and Gauteng accounted for 21%.

The Mission also found the course of the disease was more severe among unvaccinated people with risk factors, especially in older age groups.

“The disease, followed by vaccination or re-vaccination, is likely to increase the effectiveness of neutralisation and provide protection from the severe course of the disease when infected with the ’Omicron’ variant,” according to the study.

There was an increased transmissibility of the Omicron variant from person to person.

“The baseline reproductive rate increased to 2.5 in December, doubling time of 3.18-3.61 days and an increase in the positive sample rate to 35.5% with no indication of a more severe clinical course.”

Scientists of the Russian Federation said the level of monitoring in South Africa made it possible to promptly identify a new genetic variant of concern and to inform the international community of the risks associated with its spread.

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