London, June 22 : Many poorer countries lack Covid-19 vaccine doses to continue with their inoculation programmes, the World Health Organisation (WHO) has said. WHO senior adviser Dr Bruce Aylward said the Covax programme -- the international vaccine-sharing initiative -- had delivered 90 million doses to 131 countries, but it is nowhere near enough to protect populations from the deadly virus, the BBC reported on Monday. Uganda, Zimbabwe, Bangladesh, and Trinidad and Tobago have reportedly run out of vaccines in recent days. Of the 80 low-income countries involved in Covax, "at least half of them do not have sufficient vaccines to be able to sustain their programmes right now", Aylward said, at a WHO briefing in Geneva on Monday. "If we look at what we're hearing from countries on a day-to-day basis, well over half of countries have run out of stock and are calling for additional vaccines. But in reality, it's probably much higher," Aylward said. He said some countries had tried to make alternative arrangements to end shortages, with harsh consequences, such as paying above market value for vaccines. On Monday, South African President Cyril Ramaphosa called for an end to vaccine hoarding by wealthier countries as his government scrambled to curb a steep rise in cases. On a continental level, only 40 million doses have been administered so far in Africa -- less than 2 per cent of the population, Ramaphosa said. To address this, he said his government was working with Covax to create a regional hub to produce more vaccines in South Africa. Led by the WHO and other international organisations, Covax initially set a target of providing two billion doses worldwide by the end of 2021. Most of those are being donated to poorer countries, where Covax hopes to distribute enough vaccines to protect at least 20 per cent of the populations. However, the distribution of these vaccines has been hampered by manufacturing delays and supply disruptions, leading to shortages in countries wholly reliant on Covax, the BBC reported. Early this month, the Group of Seven(G7) countries -- Canada, France, Germany, Italy, Japan, the UK and the US -- also pledged to donate one billion doses of Covid-19 vaccines to poor countries to help vaccinate the world by the end of next year. Of the 100 million Covid doses, 80 million will go to the Covax programme 20 million will be shared bilaterally with countries in need. /IANS