The Omicron variant has been detected in samples from 13 people that arrived in the Netherlands from South Africa.
Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, University of Leicester, said:
“So far, the sporadic cases of the omicron variant are still imported cases.
“But once we start to see local spread within a population, i.e. cases of the omicron variant not linked to any international travel – then we will then be able to see how much transmissibility this virus has in a more typical European/Western population.
“The patterns of spread of the omicron variant in the Southern African populations may not be applicable Western populations as those populations do have much higher endemic levels of HIV and tuberculosis which may reduce host immune control of virus replication and therefore lead to higher transmissibility.
“Note that several previous variants have not spread widely in the UK, despite more widespread dissemination in their countries of origin – like the earlier beta (South African), gamma (Brazilian), lambda (from Peru), and mu (from Columbia) variants:
Prof Sheila Bird, Formerly Programme Leader, MRC Biostatistics Unit, University of Cambridge, said:
“Of around 600 passengers who flew from South Africa to The Netherlands and, on arrival, underwent PCR-testing for SARS-CoV-2, 61 were PCR-positive: 13/61 were infected by Omicron (21% of those who were PCR-positive; around 2% of those who were PCR-tested).
These results are alerting but let me outline some important caveats.
“First, there may be household-clusters among the 13 Omicron positives or clustering may have been induced by where passengers were seated on the flight from South Africa. Secondly, the immunization status of the passengers on the flight from South Africa to The Netherlands may be less favourable than applies in Europe, and in the UK in particular. Third is the age-distribution of the passengers tested; of all PCR-positives; and the ages specifically of those who were Omicron-positives . Any/all of these age-distributions may be different from the age-distribution of the general population in South Africa, let alone of the UK.
“Hence, alert rather than alarm until more is known about the household ties, seating ties, vaccination-status and age-distribution of the 13 Omicron positives versus the 48 persons who were PCR-positive but not Omicron-positive. Even my short list of four key epidemiological features makes clear that we shall need the corresponding data from more flights than the currently-reported “South Africa to The Netherlands” to account for the role of four potentially-influential factors.
“Relevant data shall accumulate fast with international co-operation. Meantime, both The Netherlands and South Africa deserve our thanks for prompt testing, diagnosis and dissemination of crucial information about Omicron.”
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