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The new Omicron variant: What we know and don’t know

01 December 2021 | Story André Damons | Photo Charl Devenish

Prof Burt read more — Prof Felicity Burt, expert in arbovirology in the Division of Virology at the University of the Free State (UFS) and the National Health Laboratory Service (NHLS).

Even though not much is yet known about the new COVID-19 variant, Omicron, the presence of a high number of mutations – more than 30 – in the spike protein of the variant raises concern.

This is according to Prof Felicity Burt, expert in arbovirology in the Division of Virology at the University of the Free State (UFS) and the National Health Laboratory Service (NHLS). According to her, although Omicron is highly transmissible, further epidemiological data is required to determine if it is more transmissible than the Delta variant.

On Friday 26 November, the World Health Organisation (WHO) declared the new variant, B.1.1.529, a variant of concern (VOC) and assigned it the name Omicron. This assignation was based on advice from the Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE), an independent group of experts responsible for monitoring and evaluating emerging variants. The following are considered when categorising a newly identified variant – are there mutations (changes in the viral genes) that are known, or that have the potential, to affect the characteristics of the virus, such as transmissibility, disease severity, immune escape, diagnostic or therapeutic escape; is there significant community transmission or increasing prevalence in multiple countries over time; are the public health and social measures effective against the variant.

With each new variant, the public health concerns are dependent on the transmissibility of the variant, the ability of the virus to escape immunity from natural infection or from vaccination, and the severity of illness caused by the variant or any change in clinical presentation. In addition, the ability of current diagnostic assays to adequately detect the variant and effectiveness of public health and social measures, must be considered.

We know, we don’t know

Answers are derived from existing epidemiological data, laboratory research, and theoretical considerations. Although we can make some predictions based on the mutations identified and the location of these mutations, the epidemiological data and laboratory research are essential to answer with certainty, and this can take some time. The presence of a high number of mutations – more than 30 – in the spike protein of Omicron, raises concern. What do we know and what don’t we know?

“What we don’t know is whether these mutations have changed the severity of disease caused by the virus. We do know that the diagnostic PCR tests currently used in South Africa are not compromised by the presence of these mutations, and in fact, one of the molecular assays commonly used to target three regions of the virus, can be used as a rapid biomarker to detect the variant. Although sequencing of the genome is used as confirmation, this assay provides a useful rapid biomarker that can be used to detect the presence of the variant; subsequently, PCR results have shown that the variant is likely already present in most provinces in the country,” says Prof Burt, who currently holds an NRF-DST South African Research Chair in vector-borne and zoonotic pathogens research.

There is also preliminary epidemiological evidence that reinfections are occurring. According to her, the occurrence of reinfections suggests some degree of immune escape; however, we do not know the extent of immune escape or the contribution of waning immunity towards reinfections. “Laboratory tests, in which the live virus is tested against samples from both recovered and vaccinated people, are required to confirm whether existing antibodies can neutralise the variant. The tests for neutralising antibodies require specialised facilities and is dependent on culturing the virus.

“These tests are already underway in the country and should provide more information in the coming weeks.

Neutralising antibody tests, although time consuming, are relatively easy to perform compared to tests to determine the role played by other arms of the immune response.”

Vaccines still best option to fight COVID-19

Prof Burt, who has worked on viral haemorrhagic fevers and arboviruses at the National Institute for Communicable Diseases (NICD), says it is known that vaccines are highly effective in reducing the severity of disease and fatalities in individuals infected with other variants, such as Beta and Delta, despite mutations in critical regions of the spike gene in the variants.

The epidemiological data acquired from cases and the results of laboratory tests for neutralising capability will contribute towards understanding the effectiveness of the vaccine against Omicron. The questions regarding severity of the disease and level of protection from previous infection and vaccines are priority areas to understand the impact of this variant. The early identification of the variant and the initiation of vital research and data analysis highlight the importance of genomic surveillance.

Cases of Omicron have already been confirmed in Israel, the United Kingdom, Europe, Australia, and Africa. Travel restrictions have previously been shown to be ineffective in stopping the geographical spread of new variants, merely delaying the inevitable, and at significant cost to economies. “We know with certainty that vaccination has reduced the severity of illness and death with previous variants; even in the face of reduced neutralising ability, there was sufficient protection to save lives,” says Prof Burt.

She concluded, “Globally, the impact of vaccination is evident in countries experiencing fourth waves, with a reduced number of deaths compared to previous waves. Many decisions in life are based on a risk assessment and consideration of the pros and cons. Vaccines save lives. Vaccines definitely boost waning immune responses from natural infection.”

“This is certainly not the time to reject the vaccine based on perceived risks from inaccurate social media spreading harmful disinformation compared to the known risks associated with contracting COVID-19 and the known protection against severe disease afforded by the vaccines.”

News Archive

Inaugural lecture: Prof Robert Bragg, Dept. of Microbial, Biochemical and Food Biotechnology

2006-05-17

Attending the inaugural lecture were in front from the left Prof Robert Bragg (lecturer at the Department of Microbial, Biochemical and Food Biotechnology) and Frederick Fourie (Rector and Vice-Chancellor). At the back from the left were Prof James du Preez (Departmental Chairperson: Department of Microbial, Biochemical and Food Biotechnology) and Prof Herman van Schalkwyk (Dean: Faculty of Natural and Agricultural Sciences). Photo: Stephen Collett

A summary of an inaugural lecture delivered by Prof Robert Bragg at the University of the Free State:

CONTROL OF INFECTIOUS AVIAN DISEASES – LESSONS FOR MAN?

Prof Robert R Bragg
Department of Microbial, Biochemical and Food Biotechnology
University of the Free State

“Many of the lessons learnt in disease control in poultry will have application on human medicine,” said Prof Robert Bragg, lecturer at the University of the Free State’s (UFS) Department of Microbial, Biochemical and Food Biotechnology during his inaugural lecture.

Prof Bragg said the development of vaccines remains the main stay of disease control in humans as well as in avian species. Disease control can not rely on vaccination alone and other disease-control options must be examined.

“With the increasing problems of antibiotic resistance, the use of disinfection and bio security are becoming more important,” he said.

“Avian influenza (AI) is an example of a disease which can spread from birds to humans. Hopefully this virus will not develop human to human transmission,” said Prof Bragg.

According to Prof Bragg, South Africa is not on the migration route of water birds, which are the main transmitters of AI. “This makes South Africa one of the countries less likely to get the disease,” he said.

If the AI virus does develop human to human transmission, it could make the 1918 flu pandemic pale into insignificance. During the 1918 flu pandemic, the virus had a mortality rate of only 3%, yet more than 50 million people died.

Although the AI virus has not developed human-to-human transmission, all human cases have been related to direct contact with infected birds. The mortality rate in humans who have contracted this virus is 67%.

“Apart from the obvious fears for the human population, this virus is a very serious poultry pathogen and can cause 100% mortality in poultry populations. Poultry meat and egg production is the staple protein source in most countries around the world. The virus is currently devastating the poultry industry world-wide,” said Prof Bragg.

Prof Bragg’s research activities on avian diseases started off with the investigation of diseases in poultry. “The average life cycle of a broiler chicken is 42 days. After this short time, they are slaughtered. As a result of the short generation time in poultry, one can observe changes in microbial populations as a result of the use of vaccines, antibiotics and disinfectants,” said Prof Bragg.

“Much of my research effort has been directed towards the control of infectious coryza in layers, which is caused by the bacterium Avibacterium paragallinarum. This disease is a type of sinusitis in the layer chickens and can cause a drop in egg product of up to 40%,” said Prof Bragg.

The vaccines used around the world in an attempt to control this disease are all inactivated vaccines. One of the most important points is the selection of the correct strains of the bacterium to use in the vaccine.

Prof Bragg established that in South Africa, there are four different serovars of the bacterium and one of these, the serovar C-3 strain, was believed to be unique to Southern Africa. He also recently discovered this serovar for the first time in Israel, thus indicating that this serovar might have a wider distribution than originally believed.

Vaccines used in this country did not contain this serovar. Prof Bragg established that the long term use of vaccines not containing the local South African strain resulted in a shift in the population distribution of the pathogen.

Prof Bragg’s research activities also include disease control in parrots and pigeons. “One of the main research projects in my group is on the disease in parrots caused by the circovirus Beak and Feather Disease virus. This virus causes serious problems in the parrot breeding industry in this country. This virus is also threatening the highly endangered and endemic Cape Parrot,” said Prof Bragg.

Prof Bragg’s research group is currently working on the development of a DNA vaccine which will assist in the control of the disease, not only in the parrot breeding industry, but also to help the highly endangered Cape Parrot in its battle for survival.

“Not all of our research efforts are directed towards infectious coryza or the Beak and Feather Disease virus. One of my Masters students is currently investigating the cell receptors involved in the binding of Newcastle Disease virus to cancerous cells and normal cells of humans. This work will also eventually lead to a possible treatment of cancer in humans and will assist with the development of a recombinant vaccine for Newcastle disease virus,” said Prof Bragg.

We are also currently investigating an “unknown” virus which causes disease problems in poultry in the Western Cape,” said Prof Bragg.

“Although disinfection has been extensively used in the poultry industry, it has only been done at the pre-placement stage. In other words, disinfectants are used before the birds are placed into the house. Once the birds are placed, all use of disinfectants stops,” said Prof Bragg.

“Disinfection and bio security can be seen as the ‘Cinderella’ of disease control in poultry. This is also true for human medicine. One just has to look at the high numbers of people who die from hospital-acquired infections to realise that disinfection is not a concept which is really clear in human health care,” said Prof Bragg.

Much research has been done in the control of diseases through vaccination and through the use of antibiotics. “These pillars of disease control are, however, starting to crumble and more effort is needed on disinfection and bio security,” said Prof Bragg.

Prof Bragg has been working in close co-operation with a chemical manufacturing company in Stellenbosch to develop a unique disinfectant which his highly effective yet not toxic to the birds.

As a result of this unique product, he has developed the continual disinfection program for use in poultry. In this program the disinfectant is used throughout the production cycle of the birds. It is also used to ensure that there is excellent pre-placement disinfection.

“The program is extensively used for the control of infectious diseases in the parrot-breeding industry in South Africa and the product has been registered in 15 countries around the world with registration in the USA in the final process,” said Prof Bragg.

“Although the problem of plasmid mediated resistance to disinfectants is starting to rear its ugly head, this has allowed for the opening of a new research field which my group will hopefully exploit in the near future,” he said.

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