The two cases are the first lawsuits brought in England and Wales over an adverse reaction to a Covid-19 vaccine.

Since the middle of last year, global vaccine production has exceeded demand with the gap continuing to grow.

Evusheld can be used for patients with immune system problems or severe reactions to other coronavirus vaccines.

The decision underscores challenges many developing countries face in their slow inoculation campaigns, as vaccines donated by wealthy countries arrive with a relatively short shelf life of just a few months or even weeks.

The interval between the second dose and booster jab for the two vaccines was originally fixed at six months.

Levels of neutralising antibodies are higher with the booster jab than with individuals who had previously been infected and recovered naturally from Covid-19.

North Korea and Eritrea are the only countries that have yet to start their vaccination campaign against Covid-19, according to the WHO.

AZD7442 or Evusheld is AstraZeneca's preventative Covid-19 shot for people who do not respond well to vaccines.

Health DG Dr Noor Hisham Abdullah says this will apply to those who were initially vaccinated with the same type of jab.

An announcement will be made once the Drug Control Authority comes to a decision.

The drug comprises monoclonal antibodies which are administered to people already infected, to make up for deficiencies in the immune system.

The group's treatment, known as AZD7442, has been undergoing phase 3 or final clinical trials to assess its safety and efficacy.