Beijing has recommended Covid-19 booster shots for high-risk and vulnerable groups, but said further study is needed before extra jabs are considered for the general public. The recommendation comes as China races to inoculate its vast population to reach herd immunity . By Thursday, more than 2 billion doses had been administered, with 1.07 billion people given at least one dose. More than 889 million people, or 63 per cent of the total population, have been fully inoculated, according to the National Health Commission. China evacuates thousands of residents along Myanmar border to stop Covid-19 spreading In recent months, some countries, such as the United Arab Emirates and Indonesia, that used inactivated vaccines by Chinese firms Sinopharm and Sinovac , have announced third doses of various technologies to boost protection for the elderly or health workers. Citing studies by Sinopharm and Sinovac, Zheng Zhongwei, head of medical science development at the NHC, said a booster shot would offer greater protection even though the levels of neutralising antibodies – an indicator of protection induced by vaccines – still dropped six months after the booster was given. The studies observed a rapid rise in the levels of antibodies three days after the third shot was given, rising to 15-30 times the original level by 14 days. Levels dropped after six months but still exceeded the peak of the two-dose vaccination. “From this perspective of immunogenicity, we feel that the protection can be enhanced with the booster shot,” Zheng said. But the boosters will only be offered to certain groups as the country is almost free of local outbreaks and the focus of Covid-19 control still lies in preventing infections from overseas, according to Zheng. “Those at high risk of importing Covid-19, such as employees involved in customs, border control, aviation, quarantine hotels, and designated medical institutions, can take a booster shot six months after completing the inoculation regimen,” he said. The commission recommended boosters for the immunosuppressed and people above 60 years old because of their higher risk of severe illness or death – and because the two-dose regime did not offer as much protection to these groups as it did to people aged 18 to 59 years old. A booster shot was also recommended for travellers to countries where Covid-19 was prevalent. “However, the experts suggest that further research is needed and overall epidemiological situation should be considered to determine whether a booster shot would be introduced for the entire population at this stage,” Zheng said. He did not say which vaccines could be offered as boosters. Inactivated, adenovirus-vectored and protein-based vaccines have been approved for use in China and some trials on mixing the technologies have been registered. But no results have been released. Zheng defended the vaccines developed in mainland China even though breakthrough infections were observed in recent outbreaks involving the more transmissible Delta variant in Nanjing, Yangzhou and Zhengzhou. Among the 1,395 infections in the outbreaks, some were vaccinated and even developed serious or even critical illnesses. But Zheng said those who completed the full regimen only accounted for less than 5 per cent of the total severe cases and less than 10 per cent of the critical cases. “It can be said very clearly that the Covid-19 vaccines have been beneficial to the control of the entire wave of Covid-19 outbreaks,” Zheng said. Coronavirus: China’s CanSino says vaccine booster shot can reverse drop in antibodies Globally, Pfizer-BioNTech is seeking US regulatory approval for a third shot after trials of a booster dose resulted in a more than threefold increase in antibodies against the coronavirus. It will also seek such approval in Europe. The United States has not approved any booster shot yet but the US Centres for Disease Control and Prevention said those who received the one-dose Johnson & Johnson Janssen shot were likely to need a booster dose. The Europe Union has yet to approve a booster and Britain has given the go-ahead for a booster for those above 50 years old starting next month.