Following the WHO's action, Chinese manufacturers of vaccines are eligible to apply for WHO "pre-qualification" status. Successful applicants are allowed to supply vaccines to the United Nation's Children's Fund (Unicef) for distribution in developing countries.

China has been producing vaccines for domestic use for the past 90 years. Thirty-six manufacturers produce 49 types of vaccines against 27 diseases, including measles, polio, BCG (TB), hepatitis B, and H1N1 (swine flu).

The second hurdle to be cleared to allow China to enter the world vaccine market is for the WHO to approve the production standards for each vaccine for which individual Chinese vaccine companies have applied for prequalification. The WHO and Chinese manufacturers are in negotiation about this process and its successful completion for the first few vaccines is expected in two to three years.

"WHO is extremely excited about China's involvement [in international vaccine production] and we've therefore made immense investment in the country, particularly in terms of training," said the organisation's vaccine director, Jean-Marie Okwo-Bele. "It will be fantastic to have another supplier from the developing world and this will hold immense advantages in terms of price and availability from which Africa will undoubtedly benefit."

Nearly half of Unicef vaccines are funded by the Global Alliance for Vaccines and Immunisation (Gavi), with about two-thirds of Gavi-eligible countries being African. Such countries receive vaccines for free, with Gavi financing inoculation for about 40-million children in poor countries each year. Cheaper prices would result in Gavi being able to buy considerably more and also a wider variety of vaccines to save more lives, particularly in Africa.

Jiankang Zhang, the programme leader in China of global health organisation Path, said China's vaccine manufacturing capacity was nearly one billion doses a year.