As a booster shot, an inhalable COVID-19 vaccine developed by China’s CanSino Biologics increased neutralising antibody levels by 250-300-fold, according to media reports.
According to the Global Times, the aerosolised inhaled adenovirus Type-5 vector-based COVID-19 vaccine (Ad5-nCoV), taken after completing two doses of inactivated vaccine shots for half a year, is proven to be safe and significantly more immunogenic than taking an inactivated vaccine as a booster.
Taking an inactivated vaccine as a booster after two inactivated vaccine shots, on the other hand, only increases neutralising antibodies by 30 times, according to the study.
According to the report, a heterologous (mix-match vaccine regimen) prime-boost regimen improves the breadth, intensity, and duration of the immune response more than a homogeneous (same vaccine regimen) booster shot.
CanSinoBIO co-founder and chief scientific officer Zhu Tao cited a previous study conducted in Turkey whose data showed that a booster dose of the mRNA vaccine widely used in Western countries for people administered in conjunction with two inactivated doses can increase neutralising antibodies by about 25 times when compared to a booster dose of the inactivated vaccine again.
A similar clinical trial was carried out by US researchers on a heterologous booster shot regimen containing three approved vaccines: one adenovirus-based vaccine from Johnson & Johnson and two mRNA vaccines from Moderna and Pfizer. The findings revealed that a heterologous regimen boosts immunity.
According to a study published recently on the pre-print server medRvix, homologous boosters increased neutralising antibody titers 4.2- to 20-fold, whereas heterologous boosters increased titers 6.2- to 76-fold.
So far, at least 13 provinces and regions in China, such as East China’s Anhui and Fujian provinces, and Central China’s Hubei Province, have initiated programmes to enhance residents’ immunity against COVID-19, the report said.