Early indicators from South Africa suggest the Omicron wave may be milder

Analysis finds a smaller proportion of deaths, and a much smaller fraction of supplemental oxygenation requirement, than in previous waves

Updated - December 08, 2021 10:29 am IST

Published - December 07, 2021 08:41 pm IST - NEW DELHI:

Photo used for representation purpose only.

Photo used for representation purpose only.

Two weeks since the emergence of the Omicron variant in the Gauteng province of South Africa, it appears that the variant is linked to a smaller proportion of deaths than previous waves of the SARS-CoV-2 coronavirus . Also, a much smaller fraction of those admitted required supplemental oxygenation than in the earlier three waves, according to an analysis of patient records by researchers at the South African Medical Research Council (SAMRC).

Though yet early, and with a caveat that the situation may change “significantly in the next two weeks ahead”, according to Fareed Abdullah, author of the analysis, “The main observation that we have made over the last two weeks is that the majority of patients in the COVID wards have not been oxygen dependent.”

Also read: With Omicron, third wave projected to hit India by Feb. but may be milder than second, says IIT scientist

The report is not a peer-reviewed medical study but a “news feature” on the official SAMRC website.

The rapid emergence of Omicron globally prompted the World Health Organization (WHO) to rapidly declare it as a ‘Variant of Concern’ and sparked a domino-like reaction, primarily among European countries, in shutting their international borders to Africa. In India, where only around three in ten persons are fully vaccinated, this has also prompted urgent discussion in the country’s top vaccine-recommendation body on whether a booster dose should be permitted, particularly among healthcare workers, the old, and the immunocompromised, given that the Omicron variant has several mutations that give it a growth advantage.

India has so far reported 23 instances of the Omicron variant , most with an international travel history from Africa. Nearly all those infected reportedly have mild symptoms.

The SAMRC researchers compared case rates and corresponding death rates over four waves of COVID-19. When case rates at the peak of the first Alpha wave (July 2020) touched 18 per 100,000 of population, the death rates approached two per million of population. In the Beta wave (January 2021), case rates hit 15 per 100,000, with a death rate peak of a little over two per million of population. The Delta wave (July 2021) saw the highest peak of 35 cases per 100,000 of population, and a death rate of around four per million of population.

In the ongoing fourth or Omicron wave , the case rate has crossed 30 per 100,000 of population — though the peak is yet to come — but the death rate per million is little over zero or even less than the Alpha wave.

Tshwane district, in Gauteng, has been the global epicentre of the Omicron outbreak, with the weekly number of cases reaching 8,569 from November 21-November 27, and jumping to 41,921 by December 3.

The scientists analysed 166 new admissions between November 14 and 29, 2021 at the Steve Biko Academic and Tshwane District Hospitals (SBAH/TDH) complex, which makes up 45% of all Tshwane district admissions in the public sector, and 26% of all admissions in both the public and private sectors for the same period.

There were ten deaths in the SBAH/TDH cohort in the past two weeks, making up 6.6% of the 166 admissions. Four deaths were in adults aged 26-36 years, and five deaths were in adults over 60 years.

A snapshot of the 42 patients in the ward on December 2, 2021 suggested that 29 (70%) were not oxygen dependent. These were patients who did not have threatening respiratory symptoms and did not need supplemental oxygen.

Of the remaining 13 patients dependent on supplemental oxygen, nine (or 21%) had a diagnosis of COVID-19 pneumonia based on a combination of symptoms, clinical signs, CXR and inflammatory markers, and the rest were sick due to non-COVID-19 causes.

“This is a picture that has not been seen in previous waves. In the beginning of all three previous waves and throughout the course of these waves, there has always only been a sprinkling of patients on room air in the COVID ward...The COVID ward was recognisable by the majority of patients being on some form of oxygen supplementation with the incessant sound of high-flow nasal oxygen machines or beeping ventilator alarms,” said Dr. Abdullah, Director of the Office of AIDS and TB Research at the SAMRC and a part-time HIV clinician at the Steve Biko Academic Hospital.

Of 38 adults in the COVID-19 wards on December 2, 2021, six were vaccinated, 24 were unvaccinated, and the vaccination status of eight patients was not known. Of nine patients with COVID-19 pneumonia, eight are unvaccinated.

“The relatively low number of COVID-19 pneumonia hospitalisations in the general, high care and ICU (Intensive Care Unit) wards constitutes a very different picture compared to the beginning of previous waves. A detailed analysis comparing the current picture with previous waves is still being conducted. This may very well be related to the early upswing of the fourth wave, with the more classical pattern becoming evident over the next two weeks,” Dr. Abdullah noted.

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