Pretoria - Researchers at the National Institute for Communicable Diseases (NICD) have noted that although the Sars-CoV-2 Omicron variant rapidly took over the country in weeks, data suggests it was a milder variant.
Yesterday, scientists from the institute presented the outcomes of research looking into the severity of the Omicron variant since it was first identified by South African scientists on November 24.
Dr Waasila Jassat, public health specialist at the NICD, said during weeks 45 to 46 they had started to see increases of infections first in the City of Tshwane and Gauteng, followed by a rapid spread to other provinces.
Jassat said unlike the previous waves of the pandemic, researchers found that this variant saw increases in almost all provinces simultaneously.
The week-on-week in-hospital admissions cases had risen to above 500%, indicating a rapid transmission in the community, whereas the hospital week-on-week increase rose to just under 300% at its peak.
Jassat said nationally, cases were peaking at a higher rate than with the Delta variant, with admissions reaching half the rate, and no significant increase in deaths.
She said the current wave also saw no trend towards increased requirements for oxygen among patients admitted to hospital and had even started on a downward trend.
Overall, the percentage of admissions requiring ventilation in both public and private hospitals were reportedly lower when compared with the previous three waves.
There were also fewer patients being treated in ICU or high care wards in both sectors, which spoke to increased immunity.
Jassat said an analysis of the first four weeks of each wave indicated that most admissions in the second and third wave were predominately among older people aged 50 to 60 plus, whereas in the fourth wave the bigger proportion of admissions were picked up in younger people under 40.
Researchers said the length of stay in the second and third waves was around 9 to 10 days on average, and increased for older people. However, with the current wave the average length of stay had been roughly three to four days for every age group.
NICD head of the Division of Public Health Surveillance and Response Dr Michelle Groome said although they could confidently say that the number of cases in Gauteng was going down, it was difficult to determine if this would be the case nationally.
As it stood, Groome said provinces such as the Western Cape and KwaZulu-Natal and other provinces had not necessarily peaked.
She said it would also be difficult to compare the effects of the Omicron variant in South Africa as opposed to other parts of the world, as those countries were experiencing winter, when respiratory viruses spread more.
Groome said while the previous immunity in other countries was as a result of vaccination, in the case of South Africa it appeared that the majority of immunity was as a result of the previous infection.
“Other data suggest that for all the other variants, previous infection was more robust against protecting you against reinfection as compared to vaccination. So infection provides strong immunity and it could be people who have been vaccinated may have less protection against severe disease with Omicron; however, it is not certain.”
Although it was difficult to predict Groome said it was likely the country would go into the next wave in a better position with even higher zero prevalence and immunity from both natural infection and vaccination.
“The data suggests that the more people are vaccinated or have experienced a previous infection, the more we will see people that end up getting the disease being break-through infections, as what has held very strongly currently is that previous immune exposure protects against severe disease,” said Dr Cheryl Cohen of the Centre for Respiratory Disease, NICD.