ISTANBUL, Feb. 3 (Xinhua) -- The mass vaccination campaign against COVID-19 continues uninterrupted across Turkey with the inactivated vaccines produced by the Chinese pharmaceutical company Sinovac Biotech Ltd.

Turkey has so far received 13.5 million vaccine doses from China in three separate shipments as part of a procurement deal of 50 million. Over 2.2 million citizens have received their first shots since Jan. 14, when the mass rollout began.

According to officials of the Turkish health ministry, the program proceeds as planned, supported by high national confidence in Sinovac's vaccines.

Clinical trial results conducted in Turkey showed the vaccine has an efficacy rate of 91.25 percent.

Professor Celalettin Kocaturk, a thoracic surgeon at Liv Hospital in Istanbul, told Xinhua that vaccine production across the globe is still far from meeting the demand.

"Considering that the world population is about 8 billion and that every person should be given double doses, it means we need about 16 billion doses of vaccine," Kocaturk said. "However, we do not have that many vaccines. Our current (annual) vaccine capacity is around 6 to 7 billion."

Yin Weidong, chairman of Sinovac, said in a recent interview with Xinhua that the company is ramping up its production to ensure global supply.

Sinovac can increase its annual production capacity to 1 billion doses with a second production line, which will be operational in February, said Yin.

"Sinovac's effort to ramp up its production is extremely valuable in that sense," Kocaturk added.

In his view, the world should be vaccinated as soon as possible, while the jabs are still effective against the coronavirus.

He also expressed the hope that Sinovac and Turkey can establish a joint production plant in Turkey.

In terms of the efficacy, Yin said that the vaccine offers broad-spectrum protection against different coronavirus variants as the serum of volunteers who received the Sinovac vaccine can neutralize the new strain found in Britain.

The company is also studying the protection offered by the vaccine against the strain detected in South Africa and will share the results in a timely manner, said the Sinovac chairman.

Sinovac will export semi-finished jabs to some countries and help them build their local filling and packaging lines to improve the production capacity and efficiency, he said.

"In this way, we can quickly improve global supply capacity," Yin said.