According to the unified deployment of COVID-19 vaccination by the authorities at state and provincial levels, Jilin Province has started administering booster doses to residents to strengthen their immunity to COVID-19. Cheng Tao, Director of Immunization Planning of the CDC of Jilin Province, answered the questions the public are concerned about in an interview with our reporter. 

Q: Why booster doses are necessary for strengthening immunity? 

A: After vaccination, the immunity of some people to COVID-19 will get weak with time, putting them in risk of getting infected. A booster dose gives such weakness a “strong rebound” with stronger antibody. The effort is of great significance to protecting vulnerable groups and preventing the spread of the pandemic. 

Q: Are booster doses safe and effective? 

A: Research findings show that no serious adverse reactions were found with those vaccinated with a third dose who had received as instructed two doses of inactivated coronavirus vaccines or one adenovirus vector vaccine six months ago. In the meantime, their antibody level increased significantly. Although the antibody level also went down 6 months after the booster shot, it was still higher than the peak after two or one dose of vaccination, indicating that the protective effect was indeed reinforced. In addition, the research of the Institute of Biophysics of the Chinese Academy of Sciences shows that the third dose of inactivated vaccine can not only increase the level of antibody but also expand its spectrum, making one stronger to resist various variants. 

Q: Who can get booster shots? 

A: The targeted for a third dose are people aged 18 or above with two doses of inactivated vaccine or one dose of adenovirus vector vaccine at least six months ago. The priority shall be given to front-line personnel at high risk of working at airports, customs, or frontier inspection, transportation, medical institutions and those in critical positions ensuring basic social operations as well as the ones to go abroad for official work or personal study, the people required so at ports, borders or for major events, or those vulnerable aged 60 or above. In addition, booster doses are available for those suitable for and willing to strengthen immunity. 

Q: Can booster doses be mixed for use? 

A: The vaccine produced by the same producer, if not, then the one produced with the same technical route, is recommended for booster shot. In principle, the people who received two doses shall get the another booster shot of the same inactivated vaccines. The ones with two different doses shall give priority to the second one for booster shot. If the second dose cannot be supplied by the same producer, the booster shot shall be based on the first dose. The people vaccinated with adenovirus vector vaccines shall still use the same ones for booster shot. 

Q: What requirements for booster shots shall we pay attention to? 

A: The procedure is basically the same as that of the first and the second dose. As for how to select a booster dose producer, the medical staff will follow as required the previous vaccination records. After vaccination, stay for 30 minutes of observation, and avoid any unexpected incident caused by strenuous exercise.