The Duke and Duchess of Sussex have called on Covid vaccine manufacturers to act with “responsibility and leadership” and increase their allocation of doses distributed to poorer parts of the world.

Harry and Meghan have written an open letter to the chief executives of pharmaceutical companies like Pfizer, Moderna and AstraZeneca urging them to redouble their support for the UN-sponsored Covax programme.

The couple have called on all firms to temporarily suspend intellectual property rights applied to Covid vaccines, and for a “global public-private collaboration” so production methods for the jabs can be shared.

The Sussexes’ intervention into the global debate about the vaccine rollout comes on the second birthday of their son Archie, and separately they have asked those wanting to mark this to donate funds which will support Covax.

At the weekend Harry appeared with a host of famous names from the worlds of music, film and politics at Global Citizen’s Vax Live: The Concert to Reunite the World, a charity performance in aid of the international Covid vaccination effort.

Speaking to an animated crowd of only fully-vaccinated guests, the duke asked for vaccines to be “distributed to everyone everywhere”, while also saluting frontline medical workers both at the concert and around the world.

Harry and Meghan, writing in their roles as Vax Live campaign chairs, said: “As of May 1, over 80% of the 1.2 billion vaccine doses administered globally have occurred in high and upper-middle-income countries while the very lowest income countries have administered just 0.4%.

“As we are seeing in countries like India, the urgency to deliver doses now to save lives and stop the spread of Covid-19 is only increasing.

“That’s why it is imperative that we ensure equitable vaccine access globally so that people are protected, economies can recover, and this global pandemic can be brought to an end everywhere.

“Therefore we, the undersigned, stand with global citizens who want to see Covid-19 vaccine manufacturers act with extraordinary purpose, responsibility, and leadership in response to this equity crisis.”

Harry and Meghan’s letter is available for the public to sign on the website of the anti-poverty movement Global Citizen, and it calls on Moderna to “move up your delivery schedule with Covax and increase the promised 2021 volume to at least 100 million doses”.

It also urges Pfizer/BioNTech “to commit at least 100 million additional doses to Covax at a not-for-profit price and to deliver them as soon as possible this year”.

Covax was set up last year to try to establish fair access to the vaccines for poor and rich nations, but huge discrepancies have emerged.

It has been reported that more than 49 million doses have been delivered through the system but more than £25 billion is still needed to ensure most adults are immunised.

While the British Government is among the biggest donors to Covax, it has come under criticism for slashing the aid budget to 0.5% of gross national income, despite the Conservative manifesto pledging to keep it at 0.7%.

Marie Rumsby, UK country director for Global Citizen, said: “The work of the Duke and Duchess of Sussex on the Vax Live campaign demonstrates how urgent the need is to act now and ensure everyone, everywhere has access to Covid-19 vaccines.

“We are grateful for their leadership in urging Covid-19 vaccine equity to help end the pandemic. We hope this will be the catalyst for many more commitments to come.”