By Nita Bhalla NAIROBI, March 11 (Thomson Reuters Foundation) - Charities in Africa slammed rich nations on Thursday for blocking efforts to waive patents for COVID-19 vaccines, saying this would prolong the pandemic for years in poorer nations and push millions across the continent deeper into poverty. More than 40 charities, including Amnesty International and Christian Aid, said Wednesday's move by Western nations to prevent generic or other manufacturers making more vaccines in poorer nations was "an affront on people's right to healthcare." Peter Kamalingin, Oxfam International's Africa director, said sub-Saharan Africa - 14% of the global population - had received only 0.2% of 300 million vaccine doses administered worldwide.