Photo: Li Hao/GT

China's top respiratory disease specialist, Zhong Nanshan, said that sufficient and enough antibodies level to prevent infection against COVID-19 would only appear at least 40 days after vaccination, in response to a recent case in Xi'an, Northwest China's Shaanxi Province. 

It is not strange to see people get infected with COVID-19 in the second week after getting the vaccine as it usually takes at least 40 days for inactivated vaccines to introduce sufficient and enough antibodies in the person to prevent infection, Zhong said on Tuesday during a program aired by Hong Kong Phoenix TV.

The comments came after a medical worker in Xi'an was confirmed positive for COVID-19 earlier this month after getting two shots of COVID-19 vaccine in late January and early February.

Zhong also added that there is no vaccine that can effectively fend off the virus 100 percent. In other words, there would be certain people who would not get antibodies or immunity against the virus.  

Zhong revealed that a study has been conducted to evaluate the efficacy of vaccines after inoculation, an important research subject.