The research team earlier invited 80 citizens who have received two doses of the Sinovac vaccine to receive a booster shot of either BioNTech or Sinovac vaccines.

For those who received a BioNTech booster shot, the level of antibodies against the original coronavirus increased to 96 percent, while the level against the Delta variant was 95 percent.

For those who received a Sinovac jab for the third dose, the level of antibodies against the original coronavirus was 57 percent, while that against the Delta variant was only 48 percent.

The results indicated that there will be a more promising and significant boost on the level of antibodies for citizens who receive the BioNTech vaccine as a booster shot.

Earlier research by Hui found at least 80 out of 375 people, or 21.3 percent, saw antibody levels in their bodies drop more than expected a month after they had completed their Sinovac vaccination.