Liam Mannix
Science reporter
Vaccine manufacturer AstraZeneca says it is awaiting fresh data on its ability to combat a new COVID-19 variant after clinical trials for rival innoculations showed reduced effectiveness against the emerging South African strain.
Late last week, Johnson & Johnson and Novavax reported earlystage clinical trial data showing their vaccines provided between 49 and 57 per cent protection against the South African variant.
In a larger trial in Britain, Novavax’s vaccine recorded overall efficacy of 89.3 per cent. Johnson & Johnson’s vaccine provided 72 per cent protection against moderate to severe COVID-19 infection on people tested in the US.
A spokeswoman for AstraZeneca said the company was waiting for studies on the vaccine’s effectiveness against the variant to be published, probably next week.
Based on early studies, Pfizer has said it does not expect a significant reduction in the effectiveness of its vaccine. The company says it can adjust its vaccine if necessary.
However, that is based on laboratory studies, not human data. And all four vaccines use different technologies but have an identical core component – a piece of the virus’ spike protein they try to generate an immune response to.
Pfizer’s vaccine was approved for use in Australia in January, and 53.8 million doses of AstraZeneca’s vaccine have been bought and will be distributed over coming months.
The federal government did not respond to questions about this story by deadline last night.
The South African variant of the virus has been picked up eight times in Australia.
‘‘It is hard to say for sure, but you would think there is the potential they would also be reduced,’’ said Associate Professor Corey Smith, head of translational and human immunology at the QIMR Berghofer Medical Research Institute. He said the results suggested the virus could mutate in ways that made antibodies and vaccines less effective. ‘‘But I don’t think that’s a real surprise,’’ he said.
The South African variant, known as N501Y.V2, has several mutations that in lab tests appear to change the shape of the virus’ spike in a way that reduces the ability of some antibodies generated from infection with the original Wuhan variant of COVID-19 from binding.
That raises concerns about reinfection, and about how well COVID-19 vaccines based on the original variant will protect against the South African variant.
Professor David Tscharke, head of the department of immunology and infectious diseases at the Australian National University, said it was always likely that ‘‘we will have to chase variants by changing our vaccines’’. However, he said it was not clear cut that AstraZeneca and Pfizer’s vaccines faced the same problems as Novavax and Johnson & Johnson. ‘‘You might guess that but the extent of that is going to be varied,’’ he said. ‘‘Although they have the same antigens, they are presented in a different way.’’
Virus-killing T cells also played a role in immunity, he said, and they might allow Pfizer and AstraZeneca’s jabs to still offer strong protection against the variant.
Early lab evidence suggested Pfizer’s vaccine would be less effective against the South African variant, but would still cover the virus.
But those studies were carried out using ‘‘pseudoviruses’’ – viruses manipulated to look like N501Y.V2 – and were done on cells in a lab.
Novavax and Johnson & Johnson are the first vaccine developers to report human data on the variants.
Novavax’s trial of more than 4400 patients in South Africa reported efficacy of 49.4 per cent (excluding HIV-positive patients, efficacy rose to 60 per cent).