Increase routine sequencing of SARS-CoV-2 viruses to catch mutations: WHO


In its advisory following the detection of a new strain of SARS-CoV-2, the World Health Organization (WHO) has called for more epidemiological and virological studies to understand specific mutations described by the UK and other countries.

This would help investigate changes in the function of the virus in terms of infectivity and pathogenicity, the WHO said, urging countries to increase the routine sequencing of SARS-CoV-2 viruses, besides sharing this sequence data internationally to report mutations of concern.

Besides the UK and South Africa, the new variant (VUI-202012/01) has been identified in several countries, including Australia, Denmark, Italy, Iceland and the Netherlands.

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“All viruses, including SARS-CoV-2, change over time, but most of these mutations or changes do not have a direct benefit to the virus or may even be detrimental to its propagation,” the WHO said, in its risk assessment. “Further laboratory investigations are required to more fully understand the impact of specific mutation on viral properties and the effectiveness of diagnostics, therapeutics and vaccines.”

Vaccinations continue

WHO Director General Tedros Adhanom Ghebreyesus said, “Viruses mutate over time; that’s natural and expected.” And while the UK had reported that this new variant transmits more easily, there is no evidence so far that it is more likely to cause severe disease or mortality, he added.

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Concern over the new variant comes even as the European Medicines Agency authorised the Pfizer-BioNTech vaccine for emergency use in the European Union member states, and the US embarked on a vaccination drive with its second Covid-19 vaccine from Moderna.

Reports suggest that Pfizer and Moderna were also testing their vaccines against the UK variant of the virus.

PCR caution

On December 14, UK authorities reported to WHO that a new SARS-CoV-2 variant was identified through viral genomic sequencing. Preliminary reports from the UK indicated that the variant was more transmissible than previous circulating viruses, with an estimated increase of between 40 per cent and 70 percent in transmissibility, the WHO said.

Even as lab studies are under way, the WHO said, “There is not enough information at present to determine if this variant is associated with any change in severity of clinical disease, antibody response or vaccine efficacy.”

The WHO also drew attention to concerns over the reported loss of performance of PCR assays that target the spike (S) gene of the virus. “Laboratories using commercial PCR kits for which the targeted viral genes are not clearly identified in the manufacturer’s instructions are advised to contact the manufacturer for more information” the WHO said.

“In order to limit the impact on the detection capacities in the countries, an approach using different assays in parallel or multiplex assays targeting different viral genes is also recommended to allow the detection of potential arising variants,” it added.

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