The United Nations Secretary-General Antonio Guterres has labeled the COVID-19 vaccination imbalance "unacceptable", as poor countries struggle to obtain the vital shots.

"It is totally unacceptable that a few countries can vaccinate most of their population while others have not had access to a single dose," Guterres said on Twitter.

"Everyone, everywhere deserves access to a COVID-19 vaccine. Only together can we end this pandemic."

The U.N. chief's comments come a day after the World Health Organization (WHO) revealed that Africa had administered just over 22 million doses, accounting for 1.69 percent of the 1.3 billion COVID-19 vaccines given globally so far.

The health agency further noted that at present, only 0.3 percent of COVID-19 vaccine supply is going to low-income countries.

The continent has struggled to obtain doses of the jabs, with the most affected countries being those that rely entirely on the WHO's COVAX facility.

Guterres last week added his voice to calls supporting the waiver of vaccine patents, which proponents argue will boost production and thus avail the life-saving shots to every country.

"It opens the opportunity for vaccine producers to share the knowledge and technology that will allow the effective expansion of locally-produced vaccines and can significantly increase the supply to the COVAX facility," the UN chief said at the time.

"We must also ensure that countries have the materials required to produce these vaccines. We are all agreed: none of us will be safe from the virus until all of us are safe."

On Friday, the WHO Director-General urged countries not to start vaccinating their young just yet, instead calling on those who have vaccinated their elderly to donate jabs to other countries that are still struggling to inoculate their high-risk populations.