A single-shot vaccine developed by Belgium-based Janssen is 85 percent effective in preventing the most serious coronavirus symptoms, according to data from mass trials released by the American giant Johnson & Johnson owned pharmaceutical company on 29 January.

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It said latest tests carried out in several countries also showed the vaccine was 66 percent effective overall at preventing moderate to severe COVID-19. "This is yet more good news from Janssen on vaccines. If this jab is approved this could significantly bolster our vaccination programme, especially as a single-dose vaccine, said the UK Health Secretary. "Once the full data has been submitted [to the Medicines & Healthcare products Regulatory Agency (MHRA), they will consider the evidence to determine whether the vaccine meets robust standards of safety, effectiveness and quality," he said.

The UK has pre-ordered 30 million doses of the vaccine, which would need to be approved by the MHRA for its deployment alongside the other vaccines already approved for use Pfizer/BionTech, Oxford/AstraZeneca and Moderna. "These topline results with a single-shot COVID-19 vaccine candidate represent a promising moment, said Paul Stoffels, Johnson & Johnson's chief scientific officer. The potential to significantly reduce the burden of severe disease, by providing an effective and well-tolerated vaccine with just one immunisation, is a critical component of the global public health response. A one-shot vaccine is considered by the World Health Organisation to be the best option in pandemic settings, enhancing access, distribution and compliance," he said.

The 85 percent efficacy rate in preventing the most severe cases "will potentially protect hundreds of millions of people from serious and fatal outcomes of COVID-19," he said, adding that it offers the hope of helping ease the huge burden placed on healthcare systems and communities. As well as being one shot, it also only needs to be kept at fridge temperature, making its storage, distribution and handling much easier. And costing around 7 pounds a dose, it is cheaper than most of the other vaccines coming in at about the same as two shots of the Oxford/AstraZeneca vaccine already being rolled out in the UK. "A single-dose regimen with fast onset of protection and ease of delivery and storage provides a potential solution to reaching as many people as possible. The ability to avoid hospitalisations and deaths would change the game in combating the pandemic," said Dr Mathai Mammen, from Janssen.

The interim data for the Janssen jab will be submitted to regulators and trials will continue, with information being fed back as part of a rolling review. The company confirmed that the injection also worked across multiple variants of coronavirus, including the South African variant. The Janssen vaccine uses a common cold virus that has been engineered to make it harmless. It then safely carries part of the coronavirus's genetic code into the body. This is enough for the body to recognise the threat and then learn to fight coronavirus. This trains the body's immune system to fight coronavirus when it encounters the virus for real. This is similar to the approach used by the vaccine produced by University of Oxford and AstraZeneca. The news comes alongside similar positive results from the Novavax two-dose vaccine, which will now proceed for the MHRA approvals process.