BEIJING -- A Chinese study has shown that having a different vaccine as the booster shot can increase the protective effect against the COVID-19 virus.

In the study, adults who had received two doses of the inactivated vaccine CoronaVac in the past three to six months were vaccinated with Convidecia, the adenovirus type-5 vector-based COVID-19 vaccine or a third dose of CoronaVac.

The post-vaccination geometric mean titer (GMT) is a key immunological parameter adequately expressing antibody response after vaccination.

According to the study published in the journal Nature Medicine, the GMT of neutralizing antibody against SARS-CoV-2 was 197.4 after Convidecia was given as the booster shot, while the GMT was 33.6 when the third dose of CoronaVac was given.

The researchers said that the data suggest heterologous boosting with Convidecia following initial vaccination with CoronaVac is safe and more effective than homologous boosting.