China considers mixing vaccines to bolster efficacy

China’s Center for Disease Control is thinking about mixing vaccines and varying the sequence of doses to boost efficacy. It is the first time a government body has discussed publicly that there are concerns over the effectiveness of Chinese jabs.

Gao Fu, the CDC head, told a forum on Saturday that the agency was “considering how to solve the problem that the efficacy of existing vaccines is not high”, according to local media.

In a now unavailable Weibo social-media post, the influential “Vaccines and Science” account said Gao’s comments were “very candid”. But it also reminded readers that taking the jab was still important for protecting the country. It added that “we can’t wait for vaccines to become perfect before getting vaccinated”.

Gao proposed mixing different vaccines as well as amending the sequence of doses, such as changing the number and quantity of doses, and the interval between them.

Some of the WeChat social-media posts on Gao’s remarks were swiftly censored, according to Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations.

“It is the first time . . . a government official publicly admitted that the protection rate is a concern in the vaccination drive,” Huang added.

China had administered 65m doses across the country by the middle of March.

Unlike other vaccine producers, China’s manufacturers have not published their phase 3 trial data, leading to accusations of a lack of transparency over their effects on different groups.

Any new strategy will have ramifications for the more than 20 countries that China said it was supplying jabs to in mostly bilateral “vaccine diplomacy” deals. As of March, China had supplied 40m doses abroad.

Chile is facing another Covid wave from new variants, despite a successful rollout of China’s Sinovac vaccine. The efficacy of one jab was only 3 per cent, compared with 56 per cent with two shots. Experts, however, have not linked the latest wave to the vaccine’s efficacy rate.

Vaccine makers in other countries have conducted dosage experiments, too. In the UK, Oxford/AstraZeneca researchers stumbled upon the efficacy of lowering the initial dose after a dosing error.

Gao also suggested mixing different vaccines. For now, the only jabs approved for use in China are the traditional “inactivated virus” vaccines produced by Sinopharm, Sinovac and other domestic groups, which are similar in mechanism to Oxford/AstraZeneca.

Sinopharm claims a 79 per cent efficacy rate, similar to the rates recently achieved by AstraZeneca in its US trials. However, while AstraZeneca revised down its rates after facing criticism for releasing incomplete data, neither Sinopharm nor any of its Chinese peers have released phase 3 data for public scrutiny.

Sinovac Biotech’s CoronaVac vaccine has an overall efficacy rate of 50.66 per cent among people aged between 18 and 60 years old, according to documents published by a Hong Kong panel of experts.

However, CoronaVac phase 1 and 2 data published in the Lancet found the shots were “safe and well tolerated”.

Gao also warned that reopening China’s borders to foreigners, who have been barred from entering the country since March last year, posed a risk to elderly people, who have not yet been vaccinated.

The timing of relaxing border restrictions will affect attendees at Beijing’s Winter Olympics in February 2022.