A group of institutional investors representing $3.5-trillion in assets under management on Thursday called on pharmaceutical companies to link their executives' pay to making Covid-19 vaccines available around the globe.

While the majority of citizens of wealthy nations are vaccinated and many are now receiving booster shots, across the African continent vaccination rates average only around 10%.

The World Health Organization has set a target of a 70% vaccination rate in every country by July 2022 in order to end the "acute phase" of the pandemic.

The 65 participating asset managers, pension funds and insurance companies signed a letter viewed by Reuters dated January 4 that was sent to the boards of Pfizer, Johnson & Johnson, Moderna Inc and AstraZeneca. The letter asks them to adopt a WHO roadmap for achieving equitable vaccine access and tying it to management pay "in a meaningful, material, measurable and transparent way".

Vaccine deliveries worldwide have been delayed by production problems, hoarding by governments of rich countries, export restrictions and red tape.

The investor group said key points include better participation in international vaccine programs and licensing and sharing technology so countries can produce vaccines locally.

"It should make business sense for a vaccine manufacturer to aim to vaccinate the whole world," said Frank Wagemans of Achmea Investment Management, one of the backers of the initiative with $225 billion in assets under management.

Other participating investors include Nomura, Investec, Boston Common Asset Management, Candriam, GAM, Aegon and PGGM.

Moderna could not immediately be reached for comment.

A spokesperson for Pfizer said the company and partner BioNTech had met a goal to deliver 1 billion doses to low and middle income countries in 2021 and would do so again in 2022.

Johnson & Johnson said in reaction that 60% of its vaccine has been shipped to low and middle income countries as of the end of 2021, and the company is in talks on a licensing agreement with Aspen Pharmacare to produce vaccine in South Africa.

A spokesperson for AstraZeneca said the company has distributed most of its supply to low and middle income countries, and it does so for no profit in those countries.

Peter Singer, Special Advisor to the Secretary General of the WHO, said the investor initiative was "extremely welcome".

The current unequal vaccine distribution represents "not only a complete moral failure for the world but also a very significant economic failure and a significant drag on the world economy", he said.

Achmea's Wagemans said he believed vaccine makers will generally be receptive to the request but the fund manager will look at how the companies put promises into action before their annual meetings.

"I cannot speak for the other signatories as to how they will vote, but for Achmea management, yes, we will vote against (executive pay packages) if there's no link made" to the WHO roadmap, he said.