Q1. Why is a booster shot needed?

A: After vaccination, some people's immunity to Covid-19 may decrease after a period of time, increasing the risk of being infected with the virus. Therefore, they need to receive a booster shot to protect them against infection. Strengthening immunization is of great significance for protecting vulnerable people and curbing the pandemic.

Q2. Who can receive a booster shot?

A: People aged 18 years and older are eligible to receive a booster shot 6 months after their two-dose vaccination.

COVID-19 booster shots are prioritized for three groups of people.

- Those with a higher risk of contracting the virus, such as customs, port, airport and health workers

- Those over 60 and individuals with weak immune systems

- Those planning to travel to overseas high-risk areas or countries for work, study or exchange reasons

Caution: Those who experienced allergic reactions during their first or second COVID-19 vaccinations are not recommended to get a booster.

Q3. Which type of COVID-19 vaccines can be used as a booster shot?

A: COVID-19 vaccines that can be used as a booster include the inactivated virus vaccines developed by Sinopharm's Beijing Institute of Biological Products, Sinovac Biotech, Sinopharm's Wuhan Institute of Biological Products or Sinovac Biotech, as well as the adenovirus vector vaccine developed by CanSino Biologics.

1.Those who have received two COVID-19 vaccine doses with the same kind of inactivated coronavirus vaccine, shall receive another dose of the same vaccine.

2.Those who have received two COVID-19 vaccine doses with different kinds of inactivated coronavirus vaccine, shall receive a booster dose that is the same as their second shot to boost immunization in principle. In case of shortage, one booster shot of the same kind as the first dose shall be used instead.

3. Those who have received adenovirus vector vaccines will receive another shot of the same kind to boost immunization.

Q4. Can we mix and match different types of COVID-19 vaccines?

A: During China's current mass immunization campaign, different types of vaccines cannot replace each other.

If a recipient is administered an inactivated vaccine, later inoculations must use the inactivated vaccine. If the recipient is given a CHO recombinant protein subunit vaccine, then the second and third shot must also be the subunit vaccine.

If a recipient cannot finish an inoculation with shots from one company, they must use the same type of vaccine to complete vaccination.

Q5. How does the COVID-19 booster shot work?

A: After a full vaccination, neutralizing antibodies will subside after a period of time. However, the body will have already produced corresponding memory-B cells.

When a booster shot is administered, it will induce memory-B cells to proliferate rapidly and produce antibodies so the human body can maintain high immunity again.

Q6. How long does it take for antibody levels to increase after getting a COVID-19 booster shot?

A: After two weeks, neutralizing antibodies in individuals inoculated with a booster shot will be 10 to 30 times higher than before.

Even six months after the booster shot, the body's antibodies can still be maintained at a relatively high level.