WHO DG has said that the deal between rich countries and vaccine manufacturers is undermining its COVAX initiative.
WHO said it would require $1.96 billion in support from its member states to continue fight against the pandemic.
Nigeria was not shortlisted for the Pfizer vaccines by the COVAX global initiative.
WHO has disclosed that around 130 countries, with 2.5 billion people, are yet to administer a single dose of COVID-19 vaccine.
A team of WHO experts visited Huanan market on Sunday, the wholesale seafood centre in the Chinese city of Wuhan.
The WHO has warned that Africa is in danger of being left behind in Covid-19 vaccination.
In-coming US President, Joe Biden has resolved to immediately return the country back to the WHO after his inauguration.
The WHO has said that the prospects of equitable distribution of COVID-19 vaccines were at serious risk.
China has announced that a team of 10 WHO scientists will visit the country on Thursday.
WHO has called on COVID-19 vaccine manufacturers and the wealthier countries buying them to stop making bilateral deals.