Because the original 2-dose mix-and-match version performed well against the deadliest Covid variant so far. Will it have one for the Omicron variant? It could by the end of next month – and have an initial 100m dose ready – but this will depend on how the first version holds up against the milder but way more infectious virus. Results from several studies in Hungary and Italy have shown that the Russian vaccine offers better protection against Omicron than Pfizer and is the best jab in preventing deaths and the second best in avoiding infections. It may also help us avoid 3-4 boosters a-year which would overload our immune system.
