According to an independent comparative study conducted at the National Institute for Infectious Diseases Lazzaro Spallanzani (Italy) by a joint team of researchers of the Institute and the Gamaleya Center showing that 2 doses of Sputnik V provide more than 2 times higher geometric mean titers (GMT) of virus neutralizing antibodies to the Omicron variant of Covid-19 than 2 doses of Pfizer vaccine (2.1 times higher in total and 2.6 times higher 3 months after vaccination).

An article by a team of 12 Italian and 9 Russian scientists led by Francesco Vaia, Director of the Spallanzani Institute and Alexander Gintsburg, Director of the Gamaleya Center, has been published in medRxiv

The study was conducted in Spallanzani Institute in the equal laboratory conditions at the Italian Spallanzani Institute on comparable groups of sera from individuals vaccinated with Sputnik V and Pfizer, with no statistically significant difference in neutralizing activity against Wuhan variant.

The advantages of Sputnik V are the use of native S glycoprotein (spike protein without proline-stabilization and other modifications) and the use of a heterologous prime-boost vaccination regimen. The Pfizer vaccine utilizes the spike protein in a proline-stabilized form in contrast to Sputnik V. Proline-stabilization and other modifications may move an immune response predominantly to the actively mutating receptor-binding domain (RBD) of spike protein. In the Omicron variant, a substantial number of mutations were registered precisely in RBD, which is why such a significant drop in neutralizing activity against this variant may be observed in the sera of Pfizer-vaccinated.

Boosting with Sputnik Light as part of the “mix & match” approach may help address the lower efficacy of mRNA vaccines against Omicron as well as the documented, quickly waning, efficacy of mRNA vaccines against COVID-19. Partnerships between adenoviral and mRNA vaccines could provide for stronger protection against Omicron and other variants.

Based on the data collected by the Spallanzani Institute and results of previous studies, heterologous (“mix & match”) boosting with Sputnik Light is the best solution to increase other vaccines’ efficacy and extend the booster protection period as optimal adenoviral platform configuration provides better protection against Omicron and other mutations.