Pharmaceutical firm Astrazeneca announced the pause of the trial Wednesday, after one of the British participants fell ill reportedly with transverse myelitis. Inflammation of the spinal cord, the participant is expected to recover. The coronavirus vaccine developed by Astrazeneca and oxford university, is seen as one of the most promising of dozens under development around the world. After successful early stage trials, it had moved to phase 3 testing in recent weeks, involving 30,000 participants in the United States, Britain, Brazil and South Africa. Scientists emphasized that there is no indication yet that the participants illness is linked to the vaccine. You're giving the vaccine to very large numbers of people. And at any given time randomly by chance, it's quite possible some of those participants may have health problems that happen to come up. So I think it's normal to expect to see these events, and what's critical is to then pause and to investigate in more detail.
That investigation is underway though it's not clear how long it might take. Britain's health minister sought to assure the public. It just shows how much of an emphasis we put on the safety of the vaccine, even though, of course, we're all desperate to see it work. This week, nine leading US and European vaccine developers issued a pledge to uphold safety standards for their vaccines. The US government launched Operation Warp Speed earlier this year, with almost 10 billion dollars of funding to accelerate the development of a vaccine, with a target date of January next year. The US Centers for Disease Control and Prevention has told health departments across the country to draft vaccination plans by October. Globally there are at least seven vaccines undergoing phase-3 trials, involving thousands of participants. It's a slow process because it depends on how many people are being infected. And of course that's spread across various different regions, and in different regions, you know that the number of cases every given week is varying from week to week. Even if a vaccine is approved, scientists say it will take time to roll out. We need to make large amounts of the vaccine. We need to fill it into little glass vials. And then we need to distribute it and then work out how to actually vaccinate people. To date, only one vaccine has been approved, the so-called sputnik 5 in Russia, which the government says will be rolled out to the Russian population starting in October. Experts have raised concerns about the vaccine safety as it has not entered phase-3 clinical trials. Henry Ridgwell for voa news London