What are the two vaccines to have yielded new results? Novavax, made by a US company but trialled in the UK, published its results on Thursday night and, within hours, Johnson & Johnson unveiled the final data from trials across the world of the single-dose vaccine made by its Belgian subsidiary Janssen. What is the efficacy of the Novavax vaccine? In an interim analysis of a phase 3 clinical trial conducted in the UK, the vaccine has shown 89% efficacy, with 27% of participants in the trial – almost 4,000 people – older than 65. That trial suggested 95.6% efficacy against the original coronavirus and 85.6% efficacy against the more recent UK variant. A less precise stage 2 trial conducted in South Africa with 4,400 volunteers, in which 90% of cases were caused by the new variant, showed 60% efficacy in preventing mild, moderate and severe coronavirus among those without HIV. Novavax said it would immediately begin to develop a new vaccine aimed specifically at the South African variant. Prof Paul Heath, the principal investigator of the UK arm of the Novavax vaccine trials, said he believed a 60% efficacy in that setting was high enough to consider using the jab, while other work continued. Heath said the Novavax vaccine had not been tested against the Brazil variant, but said the technology behind the vaccine was very adaptable. What is the efficacy of the Johnson & Johnson vaccine? The overall efficacy is 66%, but 72% in the US. That disguises some very important and exciting results. First, the vaccine had 85% efficacy against severe disease anywhere in the world – which includes South Africa where almost all participants had the variant form of the virus. That is hugely reassuring for the vaccine effort. Second, nobody in the trials who was given the vaccine was admitted to hospital or died – so 100% efficacy against the worst outcomes. About a third of the trial participants were over 60, and the results showed they were just as well protected as the younger groups, which is important because older people are most at risk. There were also no differences between people from different ethnic groups. How many doses of Novavax does each person need? Participants received two doses, 21 days apart. However, Heath said further information on the efficacy of one dose, or a longer interval, was expected. “With a standard vaccine like this, I would have very little concern about extending the interval between doses, because we know that works with these types of vaccines and indeed potentially it may even be better if there is a longer gap between two doses,” he said. How many Novavax doses will be available, and when? Subject to regulatory approval, the UK has 60m doses of the Novavax vaccine on order, to be manufactured on Teesside at a plant that is expected to be up and running in March or April, with rollout hoped for in the second half of the year. Doses can be kept in a normal fridge rather than at ultra-low temperatures. In December the EU concluded exploratory talks over a contract that would cover 100m initial doses with another 100m to follow, but that deal has not yet been signed. The US awarded Novavax $1.6bn as part of its Warp Speed programme in July with the aim of securing 100m doses by January or February. How does the science behind Novavax compare with the most prominent existing vaccines? The Novavax vaccine is different from the Oxford/AstraZeneca and the Pfizer/BioNTech vaccines. It contains spike proteins, produced by moth cells infected with a genetically modified virus, together with a substance called an adjuvant, which boosts the immune response. GlaxoSmithKline and its French partner, Sanofi, also produced a Covid vaccine based on spike proteins and an adjuvant, but trials showed it failed to produce a strong immune response in older people. Heath said it was unclear why the GSK/Sanofi was less successful than Novavax, but suggested one possibility was that the vaccines used different adjuvants. How many doses of Johnson & Johnson’s vaccine does each person need? This is the first single-dose vaccine. There are trials, including one of 15,000 people in the UK, to see whether a second dose increases the efficacy or makes it last longer, but it is considered likely that it will be mostly given as a single dose. How many Johnson & Johnson doses will be available, and when? The company said it would manufacture 1bn doses this year. Because of a shortage of vaccine factories around the world, it has been heavily investing in new ones and said it could meet that target. Because it is a single-dose vaccine, that quantity could protect 1 billion people. The vaccine, which also can be kept in a normal fridge at 2-8C and easily transported, is especially important for lower-income countries – J&J has promised 500m doses to Covax, the UN initiative to get vaccines to low- and middle-income nations. The US, which helped fund the vaccine through Operation Warp Speed, has bought 100m doses with options for more, while the UK has bought 30m doses and the EU 200m doses. J&J would not be drawn on how soon any would get their supplies. How does the science behind Johnson & Johnson’s jab compare with the most prominent existing vaccines? This vaccine is made with a similar technology to the Oxford University/AstraZeneca vaccine. It is a protein from the spike of the coronavirus, delivered to train the immune system to respond via a common cold virus. In this case, that delivery adenovirus is from humans, not chimps as with the Oxford version.