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11 August 2021 | Story André Damons | Photo Anja Aucamp
Prof Felicity Burt from the University of the Free State (UFS) and the National Health Laboratory Services (NHLS) holds an NRF-DST South African Research Chair in Vector-borne and Zoonotic Pathogens Research. She is also an expert on arbovirology in the UFS Division of Virology.

New variants of severe acute respiratory coronavirus 2 (SARS-CoV-2) have the potential to influence the size and duration of waves of infection and may prolong the duration of COVID-19’s stay with us. Despite the development of vaccines and the technology available to adapt vaccines in the future to address the emergence of new variants, it is extremely unlikely that COVID-19 will ever be eradicated.

The emergence of new variants has illustrated the importance of continually monitoring circulating variants for changes in viral proteins associated with cell binding (in other words, influencing entry of the virus into a cell) and immune responses (which would influence vaccine efficacy and reinfections). 

Prof Felicity Burt from the University of the Free State (UFS) and the National Health Laboratory Services (NHLS), who holds an NRF-DST South African Research Chair in Vector-borne and Zoonotic Pathogens Research, says the current vaccines are effective against severe disease, but do not prevent transmission. Hence, complete eradication of the virus is unlikely, as the virus will continue to circulate at low levels in the population even if high levels of vaccine coverage are achieved.  Prof Burt is also an expert on arbovirology in the UFS Division of Virology

“To date, the only pathogen that has been eradicated globally is the smallpox virus. This was achievable because of a highly efficacious vaccine and because smallpox caused a disease that was readily recognisable, enabling rapid isolation of afflicted patients. In contrast, a virus such as SARS-CoV-2 that can cause asymptomatic infections in which the person is unknowingly infected and able to shed and transmit the virus, is probably impossible to eradicate,” explains Prof Burt.  

Development of affordable treatment options remains important 

The current vaccines are, however, able to reduce the severity of the disease until a vaccine is available that prevents complete transmission of SARS-CoV-2; therefore, the development of affordable treatment options remains important. Novel therapeutics, such as an antiviral drug that interrupts replication of the virus, or monoclonal antibodies that neutralise the virus, would go a long way to contribute to the treatment of infections.  

“Currently, monoclonal antibody therapy is available in higher-income countries. Monoclonal antibodies mimic our natural antibody response, targeting specific regions of the virus, neutralising the virus, and stopping it from entering cells. Monoclonal antibodies have been used to treat other viral infections such as Ebola; however, they have significant limitations due to cost, availability, and high specificity, meaning that mutations in emerging variants could influence their efficacy. They are unlikely to be an affordable option in lower-income countries.”

Mutations become problematic

According to Prof Burt, viruses have a propensity to acquire mutations, or changes, in their genetic make-up during replication, and as expected, this virus has changed during the pandemic and will inevitably continue to mutate.

“These mutations become problematic if they influence the way the virus is transmitted between people, or if the disease profile changes and the virus causes a more severe disease, or if the changes result in a virus that is not recognised by the body's immune response.  In other words, the virus is capable of hiding from, or can escape, the immune response that a person has developed as a result of a previous natural infection or from vaccination. 

“If the virus has changed such that an existing immune response does not recognise it, then a person can become reinfected. Hence, changes in the ability to escape immunity are considered to confer an advantage to the virus. Although there are changes in all regions of the viral genes, we are concerned with changes that occur in the gene that codes for the spike protein. This protein is responsible for binding and entry of the virus into cells, hence changes in the spike protein that allow the virus to more readily enter cells are considered to be an advantage to the virus.” 

Variants of interest vs variants of concern

Prof Burt says there is now some evidence suggesting that antibodies produced in response to the Beta variant – the dominant variant during the second wave in South Africa – are less efficient at neutralising the Delta variant of the virus. In addition, there is evidence suggesting that the Delta virus can replicate to higher levels in the body, resulting in a higher viral load. Although the kinetics of each variant are still not completely understood, the combinations of higher viral load, and the potential for reinfections to occur will likely contribute towards a larger wave of infection.

“The World Health Organisation (WHO) and international partners characterise emerging variants as variants of concern (VOC) or variants of interest (VOI). Although there are multiple new variants globally, only a small proportion of these meet the definition. The Lambda variant, initially recognised in South America, is deemed a VOI. This is a level below VOC, indicating that it has mutations that are known or have the potential to affect the characteristics of the virus and that the prevalence is increasing in multiple countries over time. Currently, Lambda is not a concern in SA. In contrast, a VOC has the same characteristics as a VOI, but in addition, has one or more of the following: increased transmissibility or is associated with change in disease severity or clinical presentation, or the public health and social measures are less effective against the variant,” says Prof Burt.  

Vaccines will likely need to be adapted to accommodate future variants 

It is impossible to predict which variants may emerge next, explains Prof Burt. “Fortunately, although the current vaccines may not prevent mild disease, they have all been shown to reduce the incidence of severe disease and fatalities. The technology for adapting vaccines is available – but of course – if a vaccine has to be adapted, it will take some time for that to be available. As this virus is now well established globally and will continue to evolve over the years, it is likely that, in the future, vaccines will be required to be adapted to accommodate circulating variants.”

“Although there is some reduction in vaccine efficacy against the currently circulating variants, there are fortunately high levels of protection against severe disease and hospitalisation in people who have received the single-dose Johnson & Johnson vaccine or both doses of the Pfizer vaccine. In other words, they are fully vaccinated,” says Prof Burt. 

Despite reduced effectiveness and potential for vaccine breakthrough, it is still important for people to be vaccinated, as it reduces viral load and duration of virus shedding. Less viral replication means that the virus has less chance to mutate, with less chance of new variants emerging.   

News Archive

HIV/AIDS could kill 20% of southern Africa’s farm workers by 2020
2008-09-27

HIV / AIDS is claimed to account for 40% - 50% of infections in the workforce in some labor-intensive industries. This means that every farmer will have to replace up to 50% of his workforce within the next 10 years.

This was said by Mrs Estelle Heideman (pictured) of the Faculty of Natural and Agricultural Science at the University of the Free State (UFS) at the launch of a DVD about a project to equip farm workers with knowledge and skills regarding HIV / AIDS.

Mrs Heideman was quoting the research findings of Agrimark Consultant, Johan Willemse, and added that farm workers, because of low literacy levels, remoteness of the areas in which they live and the distances to health care facilities, are often forgotten when it comes to HIV/AIDS prevention and care programmes.

This weekend Mrs Heideman leaves for New York City to take up a scholarship awarded to her by the University of Columbia and the University of California, Los Angeles (UCLA) to participate in the M-A-C AIDS Sponsored Leadership Programme.

The leadership Initiative provides a structured support program to enable participants to exchange best practices in the approach to HIV prevention that can be adapted to local circumstances. At the conclusion of the program the Leadership Initiative will, amongst other benefits, provide funds for Fellows to carry out their prevention program in South Africa.

Such a program was already carried out from February to May this year as part of the Lengau Agri Centre’s Farm Project in collaboration with the Chief Directorate Community Service at the UFS on the farms Slangfontein, Dwarsrivier and Pypersfontein in the Philippolis district.

According to Mrs Heideman, who is the co-coordinator of the project, the aim of this project was to equip farm workers with knowledge and skills regarding HIV/AIDS so that they can take control of their lives and make quality decisions.

“A major advantage of working with farm workers is that the whole family is included in the session and this ensures that all generations get the same message”, she said.

At the end the feedback from the farm workers about the programme was positive. “Many said they had tested for HIV and will continue to do so to ensure that they would be around to see their children grow up”, said Mrs Heideman.

Copies of the DVD can be obtained from Estelle Heideman (0828211230) or Tarryn Nell (0832573843).

Media Release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt.stg@ufs.ac.za  
26 September 2008


 

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