Since many variants are emerging continuously everywhere, it is not possible to measure how transmissible or more severe a given variant is with respect to others that have already circulated worldwide or that are circulating today. On the other hand, of the thousands of variants that are emerging on the SARS-CoV-2 genomes, it is reasonable to expect that some variants can eventually achieve biological advantages and be more transmissible, clinically aggressive or resistant to treatments or vaccines. Moreover, explanations other than genetic advantages, such as the randomness associated with the model of infection (e.g. super-spreaders hosts or events) and social behaviour, can also explain the predominance of a particular strain.
While mutations of SARS-CoV-2 are expected, it is important to continue to monitor the public health implications of new virus variants. WHO routinely assesses if variants of SARS-CoV-2 result in changes in transmissibility, clinical presentation and severity, or if they impact on countermeasures, including diagnostics, therapeutics and vaccines. Meanwhile, current disease control measures recommended by WHO continue to be effective and should be adapted in response to increasing disease incidence, whether associated with a new variant or not.