Exactly two years ago Prof Sir Andrew Pollard was starting to panic. “We were just waking up to the reality of Covid-19 and that we would need vaccines for our very survival,” the director of the Oxford Vaccine Group told the Guardian last week. He joined forces with a colleague, Prof Dame Sarah Gilbert, and together they launched one of the greatest medical missions in modern history. Their seemingly impossible task – to design, develop and deliver a vaccine from scratch to slow the advance of a lethal pandemic – was completed in less than 12 months, to the relief of millions. Today though, the coronavirus landscape – and the status of their jab, ChAdOx1 nCoV-19 – looks very different. In the UK, half the population have had their vaccine, restrictions have ended, and while cases and hospitalisations are rising in the UK, a dramatic uptick in deaths is not expected. The jab has saved more than a million lives, according to estimates, but its reputation has been battered by a toxic mix of misinformation, miscommunication and mishaps. Two years after Pollard, Gilbert and their teams first began making the miracle jab now known as Vaxzevria or Covishield, it has been sidelined in the UK and Europe, and snubbed in the US. Instead, ChAdOx1 nCoV-19 is gearing up for what will probably be its final act: saving the rest of the world. About 2.6bn doses of it have been distributed to 183 countries, but 3 billion people have yet to receive a first dose of any Covid jab. The highly infectious Omicron variant is flagging in the west, but new cases are soaring in less-vaccinated areas. Globally, daily cases remain high, averaging about 1.8m – three times the 600,000 a day in December. Cases are rising in the Middle East, Asia and Latin America, and the low cost and ease with which the Oxford/AstraZeneca vaccine could be deployed to these regions, as well as the more “inaccessible parts of the world”, meant the jab could still play a crucial role in helping end the pandemic, Pollard said. “Protecting people elsewhere is also important for our own defence,” he added. The current vaccine gap could open the door to a deadly new variant, which is why he believes the Oxford/AstraZeneca jab’s ultimate legacy will be to build a “global wall of immunity” in 2022 – saving more lives in low- and middle-income parts of the world but also slashing the risk of new variants arriving in the UK and elsewhere. While Pollard takes “huge satisfaction” from “a team of boffins” developing a jab that has been so widely used, he admitted the last two years had not been straightforward, adding: “Misinformation has undermined confidence in the vaccine.” Particularly damaging, he said, was a story from Germany in January 2021 incorrectly claiming the jab had only 8% efficacy in elderly people. Looking back at the behaviour of politicians who pushed the “nonsense” claims, Pollard was scathing. “President Macron amplified the story globally by claiming the vaccine was ‘quasi-ineffective’,” he said. “It is difficult to fathom why he would make such a comment in the midst of the Alpha wave with thousands dying across the continent, but the damage was done.” Hours later the European Medicines Agency approved its use for all ages, but many countries still opted not to use the vaccine for their elderly people. “The rhetoric undermined confidence in the vaccine, undoubtedly costing lives,” said Pollard. Delayed deliveries and lower efficacy rates than mRNA jabs have also not helped the Oxford/AstraZeneca cause. But other scientists have a different take on the jab’s bumpy ride – suggesting those involved with its development are also to blame. The lack of older people in its trials compared with the mRNA studies, for example, was a “big issue”, Prof Paul Hunter, of the University of East Anglia, told the Guardian. “Given that these age groups were always going to be the number one priority, not including them was a mistake.” Dr Julian Tang, a clinical virologist at Leicester University who previously worked on respiratory virus outbreaks in Hong Kong and Singapore, is also critical of the “overly complex” early Oxford/AstraZeneca trials. Reflecting on them this week, what still strikes him now was their “uneven make-up” with “no elderly initially, and few BAME participants”. Hunter and Tang also raise the dosing debacle. A blunder meant some doses given to volunteers were only half-strength. The initial half-dose jab received by about 3,000 British patients proved far more effective than the full dose that up to 20,000 Brazilians received. The efficacy rate in Britain was 90%, compared with 62% in Brazil. The overall rate of 70% sowed huge confusion, especially when compared with the much clearer results of trials by Pfizer and Moderna. The final straw for some came in March 2021. A link between the jab and rare blood clots emerged, which partly explains why the UK now favours other jabs as boosters. In December, Menelas Pangalos, the executive vice-president for research and development at AstraZeneca, said the company hoped to tweak its recipe to avoid the issue. However, the Guardian has learned the company has since abandoned that idea – because it has still not identified the cause. “This being the case we are not at this time looking to modify the vaccine,” a spokesperson confirmed this week. Two years after the jab’s inception, Pascal Soriot, the chief executive of AstraZeneca, insists he has no regrets. “It is really hard to regret anything when you have delivered 2.6bn doses of vaccine, saved 1 million lives around the world and enabled economies in many countries to restart,” he said. “A lot of people focus on some of the challenges that we faced in parts of the world, but I would like to remind everybody again that the US and Europe represent about 10% of the world’s population.” Indeed, a data analysis for the Guardian by Airfinity, the health analytics company, reveals that despite the jab’s trials and tribulations, it is already reaching every corner of the globe. Among the 2.6bn doses delivered, 166m have gone to Brazil, 84m to Mexico, 60m to Vietnam, 54m to the Philippines, 19m to Nigeria, and 16m to Iran, for example. Even Germany and France, once the sources of slipshod reporting and false claims about the jab, have quietly accepted 31m and 10m doses respectively, the analysis reveals. Despite the early “excessive hype”, Tang says it remains an “effective” and “useful” vaccine that can still play a big role. “The AZ vaccine is cheap, easy to store and its overall efficacy is still generally sufficient to roll out across many countries to offer protection against severe Covid-19.” Designed to be sold not-for-profit – for about £3 a dose, a fifth of the price of Pfizer’s jab – it recently started turning a modest profit. Rivals have made tens of billions of dollars but Pollard calls AstraZeneca “morally brave” for ignoring the “perverse commercial incentive in a pandemic to sell first to the rich”. A spokesperson says low-income nations will continue to receive the vaccine on a not-for-profit basis. AstraZeneca is under contract to deliver a further 1.4bn doses worldwide this year, according to a second Airfinity data analysis for the Guardian. “We estimate these [orders] will be fulfilled by the autumn,” said Matt Linley, Airfinity’s analytics director. Some of AstraZeneca’s 25 facilities in 15 countries will reduce their output after that, he expects. “However, we do not foresee demand for the AstraZeneca jab ending completely,” Linley added. “There will remain a need for it, although at a much lower level, especially in difficult to reach parts of the world.”