Researchers to combine Sputnik V with British AstraZeneca vaccine

AstraZeneca will start clinical trials to test a combination of its experimental COVID-19 vaccine with Russia’s Sputnik V shot, says Reuters citing Russia’s Direct Investment Fund (RDIF). The British company will soon begin exploring with Russia’s Gamaleya Institute, which developed Sputnik V, whether two common cold virus-based vaccines can be successfully combined. The cooperation between the two institutions highlights the pressure to develop an effective tool to fight the pandemic.

Last month, the developers of Sputnik V urged AstraZeneca to try the combination after the publication of interim results of the British vaccine’s late-stage trial. According to the RDIF, the British drugmaker accepted the proposal. The trials will start by the end of the year, and if the new vaccine is proven to be effective, Russia wants to jointly produce it, said the fund. “The decision by AstraZeneca to carry out clinical trials using one of two vectors of Sputnik V in order to increase its own vaccine’s efficacy is an important step towards uniting efforts in the fight against the pandemic,” commented head of the RDIF Kirill Dmitriyev. He added that other vaccine producers might follow the example.

The move is likely to be considered as a long-awaited vote of confidence by a Western manufacturer in the Russian vaccine. While its clinical trials are still underway, the developers have already stated that the shot’s efficacy rate exceeds 90%, which is higher than AstraZeneca’s own vaccine and similar to those of Pfizer and Moderna. However, some Western scientists have criticised Russia for giving the regulatory go-ahead for its vaccines and launching large-scale vaccinations with Sputnik V before completing full trials.

Sputnik V and AstraZeneca’s vaccines are both using harmless adenoviruses to prompt cells to produce vaccine proteins. This approach has previously been used in an Ebola vaccine. However, the immune system can attack the adenovirus vehicle, known as the viral vector, and, in particular, neutralise the staggered booster shot. Thus, researchers including those from the Gamaleya Institute are using different viral vectors for the primer and booster shot. Combining vaccines from different developers may also help avoid the problem.

Chair of the UK’s Vaccine Taskforce Kate Bingham said last week that the country would start trials of combinations of different kinds of vaccine for the initial and booster vaccinations next year. Such a “mix-and-match” approach may maximise the immune response.