Moderna says studies show its vaccine is effective against emerging strains of the coronavirus but plans to test a booster to its two-dose regimen.

Source: COVID: Moderna says vaccine protects against UK, South Africa variants

Does note that it might be less effective against the South Africa strain, but they are also developing a “booster shot” to be given later which will address that.

Meanwhile, Merck has abandoned its vaccine efforts after its vaccine candidate did not meet effectiveness goals.