Pfizer, AstraZeneca, Moderna. Britons have become so accustomed to the three Covid vaccines available in the UK that most have forgotten about another jab, Novavax – even though the government has ordered 60m doses and hundreds of British jobs depend on it. Late last month the US company, with a factory on Teesside primed to manufacture doses, submitted final data to UK regulators and a positive decision is anticipated within days or weeks. It will bring to an end what feels like a long wait compared with the speedy development and approval of the other jabs, including for those who took part in trials. So what difference would this additional weapon make to the UK’s vaccination armoury? Novavax’s offering is a protein-based jab – similar to those used to protect against flu, and for routine childhood vaccination against pertussis (whooping cough) or meningococcal infection. Other protein-based Covid vaccines are also in late-stage clinical trials, including one being developed by Sanofi and GSK, again with 60m orders from the UK. Final data from its phase 3 trial is expected any day now, paving the way for the companies to seek regulatory approval. Whereas existing UK Covid-19 jabs instruct our cells to manufacture the coronavirus spike protein, protein-based vaccines deliver pre-made fragments of it alongside an immune-stimulating adjuvant. Clinical trials suggest that two doses of the Novavax jab have an efficacy of about 90% against symptomatic Covid – similar to the other approved UK vaccines. It is also undergoing “mix and match” testing with the Oxford/AstraZeneca or Pfizer/BioNTech jabs and preliminary data suggest it generates a robust immune response when given as the second dose. But it is the emerging signs of reduced side-effects that could make Novavax particularly attractive. Trial data appear to show the potential for lower “reactogenicity” compared with existing jabs, meaning side-effects such as injection-site swelling, fatigue, headaches and muscle pain occur less frequently. No direct head-to-head comparisons have yet been done, however, and further studies are needed. “Lower reactogenicity becomes particularly important in groups such as children, where the balance between vaccination and not vaccination becomes a little less clear, simply because, for example, in young children the likelihood of them having severe Covid-19 is so small,” said Prof Paul Heath, the director of the Vaccine Institute at St George’s, University of London, and chief investigator of Novavax’s UK trial. However, a caveat with any new vaccine is that rarer side-effects may not become apparent until a vaccine is used widely, said Azeem Majeed, professor of primary care and public health at Imperial College London. “Post-marketing surveillance would be needed to identify any previously unknown side-effects,” he said. The fact that it uses a more established vaccine technology could also make it more appealing. Heath said: “It may well be that those people who have been hesitant about receiving other Covid vaccines may be more open to receiving a vaccine that uses this protein adjuvant technology; it may be something that’s more familiar to them, and therefore will be happy to receive.” Majeed is less convinced Novavax will make much difference to uptake but can see other benefits to such protein-based vaccines. It can be stored in a standard vaccine fridge at 2C to 8C, making it easier to transport and store than mRNA-based vaccines. He said: “The AstraZeneca vaccine has similar storage requirements to Novavax but the UK government seems to have largely stopped using it.” Access to a broader range of vaccines would also be helpful if regular booster shots are needed in the future. “Because of Novavax’s simpler storage requirements, it would be easier to use in GP surgeries and pharmacies,” said Majeed. This combination of easier transport and storage is even more important in developing countries, where low temperature-controlled supply chains are less well established. “Worldwide, the more vaccines the better, particularly if they are low cost and don’t require freezing for storage and delivery,” said Brendan Wren, professor of microbial pathogenesis at the London School of Hygiene and Tropical Medicine. Jobs could come alongside the new jab, too: in March, Boris Johnson announced that 60m doses would be made in north-east England. Fujifilm Diosynth would manufacture them at its plant in Billingham, while GSK would fill and finish them – package them up in vials – at its operation in Barnard Castle. About 300 people at FujiFilm are said to have been working on the vaccine, though delays had prompted concerns that jobs would be hit. Fujifilm last month said manufacturing was unaffected by the delay, and it planned to expand its workforce in the years to come. The local Labour MP, Alex Cunningham, who represents Stockton North, met with a representative of Novavax and said he felt reassured. “I don’t know how long the approvals process will take but hope production will get up and running soon,” he said. The Novavax jab has already been approved for use in the Philippines and Indonesia. On 4 November, the company submitted an emergency use application to the World Health Organization. If approved, it would be the first protein-based vaccine to be recommended by the WHO. Novavax told the Guardian that it was now routinely producing high-quality product at commercial scale at multiple sites across the world. The Serum Institute of India is also manufacturing doses, 20m of which have been approved for export to Indonesia. Silvia Taylor, the senior vice-president of global corporate communications and investor relations at Novavax, said: “Now that the submission [to the UK Medicine and Healthcare products Regulatory Authority] is complete, the timeline is in the hands of the regulatory agencies.”