The government has approved China’s CanSinoBio Covid-19 vaccine for emergency use in Pakistan, Special Assistant to the Prime Minister (SAPM) on Health Dr Faisal Sultan said on Friday.

“Yes, Correct,” Sultan texted Reuters after being asked to confirm that the Drug Regulatory Authority of Pakistan (Drap) had met and approved the vaccine.

Drap has already approved three other vaccines for use in Pakistan — China's Sinopharm, Russia's Sputnik-V and the Oxford University-AstraZeneca vaccine.

CanSinoBIO last week released interim efficacy results of a multi-country trial, which included Pakistan, showing 65.7 per cent efficacy in preventing symptomatic coronavirus cases and a 90.98pc success rate in stopping severe infections.

In the Pakistani subset, the efficacy of the vaccine at preventing symptomatic cases was 74.8pc and 100pc at preventing severe disease.

Although Covid-19 vaccines from Chinese developers have shown lower protection rates than some Western ones, and no detailed study results are publicly available yet, they have already been approved in several developing countries battling a surge in coronavirus infections.

Besides Pakistan, the CanSinoBIO vaccine is being tested in Mexico, Russia, Argentina and Chile, according to clinical trial registration data, and the company has supply deals with some of those countries, including Mexico.

SAPM Sultan had said that Pakistan could receive “in the range of tens of millions” of the vaccine under an agreement with the Chinese firm. On another occasion he said the country is entitled to receive 20 million doses of CanSino's vaccine, "provided the results are positive and the vaccine proves to be effective".

Hassan Abbas, head of the CanSinoBIO trial at AJ Pharma in Pakistan, earlier said it had already applied to the government for permission to import the vaccine.

“The initial set of vaccines will come in vials already filled, but we hope in the future to get them in the form of concentrates from CanSino, and do the filling here in Pakistan,” he told Reuters.

No serious safety concerns were raised in the study, Sultan said.

Single-dose regimen

While the vaccine's protection rate trails the more than 90pc efficacy of shots developed by Pfizer Inc and its partner BioNTech SE and Moderna Inc, its single-dose regimen and normal refrigerator storage requirement could make it a favourable option for many countries.

CanSinoBIO's vaccine — which was approved for use in the Chinese military last year and has since been given to at least 40,000-50,000 people — uses a modified common cold virus known as adenovirus type-5 (Ad5) to carry genetic material from the coronavirus protein into the body.

However, researchers in an early and mid-stage trial report expressed concern the vaccine may not work in those previously exposed to Ad5, as the pre-existing antibody against the common cold virus could weaken the vaccine-triggered immune response.

CanSinoBIO is also testing a two-dose regimen of the vaccine in China including on participants aged between six and 17 and older than 55.

Shots from Chinese companies Sinovac and state-backed Sinopharm have shown efficacy of between 50pc and 91pc.

The three firms have applied to join the global vaccine sharing scheme Covax for approval and China plans to provide 10m doses to the initiative, which is backed by the World Health Organisation and GAVI vaccine alliance.