The latest update from WHO on the new SARS-CoV-2 variant suggests that scientists still do not know whether it is more transmissible than the Delta variant. Speaking on behalf of WHO, epidemiologist Maria Van Kerkhove said “We don’t have all the information yet on transmission; if it is more transmissible (than delta)”.
Dr. Kerkhove however said that available information hints at this being the case. She told reporters “there is some suggestion of this (Omicron being more transmissible than Delta). But, again, it is still early days”.
Omicron is a heavily mutated variant of SARS-CoV-2, with over 50 mutations. Over 30 these mutations are in the spike protein. The Delta variant, in contrast, has less than 20.
But, it remains unknown whether the greater number of mutations translates to better transmissibility. As of November, the Delta variant was responsible for the majority of COVID-19 infections worldwide. Studies conducted in the US and the UK estimated that as much as 99% of new infections were caused by this variant.
Newer variants of SARS-CoV-2 that spread rapidly are often sufficiently mutated to evade immune response. If Omicron successfully outcompetes the Delta variant, scientists fear that immunity gained from prior infections or vaccines may be less effective against it.
“One of the scenarios is that the virus, as it continues to evolve, may still have a fitness advantage; meaning that it could become more transmissible. More transmissible than Delta? We’ll have to see.”
Maria Van Kerkhove, COVID-19 Technical Lead @WHO
According to the WHO, adequate information to determine Omicron’s transmissibility will likely be available within days, and not necessarily weeks. Dr. Kerkhove also declined to speculate on the severity of disease caused by Omicron, saying “we have seen reports of cases with Omicron that go from mild disease all the way to severe disease”.
