Reconstructed spread of ‘Eta’ shows challenge of tracking virus globally
A variant of SARS-Cov-2 might have warranted “variant of concern” status due to its spread in Nigeria if it had been spotted quicker, a study has found.
A predominantly Nigerian team of researchers found that the Eta variant displaced Alpha in the country during the latter part of 2020 and early 2021 before being replaced by Delta in June. But this went largely unnoticed at the time.
“The ability of Eta to outcompete Alpha in West Africa, coupled with the evidence of increased infectivity in vitro and enhanced immune evasion after natural infection, suggest that Eta may have warranted designation as a ‘variant of concern’ had its expansion potential and phenotypic characteristics been recognized earlier,” the researchers say in their 3 February Nature paper.
The World Health Organization did not designate Eta as a variant of concern, as it did with other fast-spreading variants including Omicron, discovered by South African researchers. Scientists complained that the effectiveness of South Africa’s surveillance and genomics networks was subsequently “punished” by the imposition of travel restrictions.
The Nigerian authors of the Nature paper say their results demonstrate clearly that international cooperation in disease surveillance is needed in undersampled regions to combat new variants. They say phylodynamic reconstruction suggests that Eta originated in West Africa.
The authors say their results also show that the viral dynamics of the pandemic are distinct in West Africa, which may also be the case in other undersampled parts of the world.
“These results underline the critical importance of improving genomic surveillance efforts to better understand and monitor new variants as they arise in distinct regions of the globe,” the authors write.