The world needs a "quantum leap" in funding for Covid-19 vaccines, the UN head has said as donors raised $700 million - less than half the target - to purchase any future vaccines for poor countries and global deaths passed 900,000. UN Secretary-General Antonio Guterres urged countries to find $15 billion over the next three months to fund the ACT-Accelerator programme, a global collaboration to hunt for a vaccine and treatments led by the UN's World Health Organization (WHO). "Either we stand together or we will be doomed," Mr Guterres said as he called the virus the "number one global security threat". "We need a quantum leap in funding to increase the chances of a global solution to get the world moving, working and prospering again," he said. According to the WHO's latest overview, 35 candidate vaccines for the virus are being tested on humans, of which nine have reached Phase III trials where they are tested on tens of thousands of people. A further 145 candidate vaccines are in earlier testing phases. Typically only about 10 per cent of candidate vaccines succeed. Meanwhile, the global health initiative to ensure eventual vaccines do not go only to rich countries, named COVAX Advanced Market Commitment, has an initial target of $2 billion to buy vaccines. "Up to today, what has been mobilised so far is $700 million... So, there is a great deal of work to be done to diversify the possible sources of funding," Matshidiso Moeti, Africa regional director for the WHO, told an online press briefing. COVAX aims to deliver 2 billion doses of effective, approved Covid-19 vaccines by the end of 2021. At least eight African countries, including South Africa, Gabon, Namibia and Equatorial Guinea had agreed to self-finance access to the vaccine, Mr Moeti said. But worldwide cases and deaths continued to rise with 27.7 million now having tested positive for the virus and over 900,000 having died of the disease. The United States remains the world’s hardest-hit nation, with over 190,00 deaths and 6.3 million cases. America is trailed by Brazil with 127,00 deaths and then India with 74,000 deaths.