Developers of Russia’s COVID-19 vaccine, Sputnik V, have told British pharmaceutical firm AstraZeneca to try combining its experimental vaccine with Russia’s, in order to boost efficacy.

“If they go for a new clinical trial, we suggest trying a regimen of combining the AZ shot with the #SputnikV human adenoviral vector shot to boost efficacy,” the developers of the Russian shot tweeted.

“Combining vaccines may prove important for revaccinations,” it added.

Sputnik V, developed by Gamelya Research Institute, has said its vaccine candidate is 92% effective at protecting people from COVID-19.

AstraZeneca has said its vaccine candidate showed 70% efficacy. The British firm has said it will have as many as 200 million doses of its vaccine by the end of 2020.

The vaccine is offering the best hopes in the underdeveloped, developing countries because of its cheaper cost. Its also beneficial for those with warmer climates because of its transportation at normal fridge temperatures, as compared to other vaccines who need lower temperatures.