STOCKHOLM, March 9. /TASS/. Sweden’s Umea University scientists have discovered the reason why certain COVID-19 vaccines act differently to what was initially expected. The study they conducted helps us to understand the mechanism behind higher efficiency of vector-based vaccines such as the Johnson & Johnson jab produced in the US and Russia’s Sputnik V, SVT channel reports.

Such shots pierce into body cells through adenoviruses and launch antibody response when inside. However, the Swedish scientists who joined forces with their German and Dutch colleagues found out that some vaccines use a different entry mechanism to what was believed previously, which explains their higher efficacy rates.

"This is how it works, the vaccine ‘gets a free ride’ to the cells and when there uses protein as a key to open up cells and transfere the gene responsible for launching antibody production," Niklas Arnberg, virology professor at Umea University, said. "It was previously believed that vaccines relying on adenoviruses as a transportation agent used spike protein as a key to get into cells. However, when we tried to reproduce this in a lab, we failed. Then, we started researching a different protein, the so-called hexon protein, and discovered that it is precisely what acts as a cell key."

At the same time, Arnberg highlighted the better level of protection provided by the Russian vaccine. "Johnson & Johnson offers inoculation with one dose, while the Russian vaccines needs two. This will likely lead to Sputnik V ensuring better protection than Johnson & Johnson," he commented.

The Umea University study is published in the PNAS scientific journal.