The WHO has recently warned about the Delta variant that is a significantly more transmissible strain of coronavirus and is expected to become a “dominant lineage” if current trends continue. This warning has come after this variant has been reported in 85 countries and continues to be detected in more places around the world.
An updated data has been released by the World Health Organisation (WHO) on June 22 in the COVID-19 Weekly Epidemiological update. This data said that globally the variant Alpha has been reported in 170 countries, territories or areas, Beta in 119 countries, Gamma in 71 countries and Delta in 85 countries.
The update said, “Delta, now reported in 85 countries globally, continues to be reported in new countries across all WHO Regions, 11 of which were newly reported in the past two weeks.”
The current four variants that are considered to be the ‘Variants of Concern’ are being closely monitored, the Alpha, Beta, Gamma and Delta – are widespread and have been detected in all WHO regions, said WHO.
“The Delta variant is significantly more transmissible than Alpha variant, and is expected to become a dominant lineage if current trends continue.”
“Decreasing trends in the weekly case and death incidence in the Region are predominantly associated with decreases reported in India,” the update said. New evidence has been published on the phenotypic characteristics of the Delta variant has been noted in the detailed update released on June 8.
“A study from Singapore showed that infection with Delta variant was associated with higher odds of oxygen requirement, intensive care unit (ICU) admission, or death,” it said. Further, a study in Japan “estimating the relative instantaneous reproductive number (a measure of transmission at a specific point in time) showed that the Delta variant was associated with greater transmissibility” when compared to the Alpha variant.
The update noted, “when compared with the variants circulating in Japan before December 2020, the relative instantaneous reproduction number for Alpha was estimated to be at 1.56 and for Delta 1.78. Overall, this study showed Delta was associated with 1.23 times higher transmissibility than Alpha.”
This update has taken noted from two studies to provide the proof of the effectiveness of Pfizer BioNTech-Comirnaty and AstraZeneca-Vaxzevria vaccines against the Delta variant. On the effectiveness of these vaccines against severe disease (hospitalisation) due to Delta among persons over the age of 16 years in the United Kingdom, was studied and it was found that vaccine effectiveness estimates against hospitalisation due to Delta and Alpha variants over 14 days post second dose was estimated to be 96 per cent and 95 per cent respectively for Pfizer BioNTech- Comirnaty and 92 per cent and 86 per cent respectively, for AstraZeneca-Vaxzevria.
The study further found that over 21 days after immunisation remained high for Pfizer BioNTech-Comirnaty at 94 per cent against Delta and 83 per cent against Alpha with single dose that was effective against hospitalisation.
Two doses of Pfizer BioNTech-Comirnaty were 83 per cent and 79 per cent effective against symptomatic disease and infection due to Delta. respectively, over 14 days after receipt of second dose in persons 15 years and older.
“Together, these studies suggest moderately reduced VE at preventing symptomatic disease and infection due to the Delta variant as compared to Alpha…The studies also provide further evidence of the importance of two doses of both Pfizer BioNTech-Comirnaty and AstraZeneca-Vaxzevria in preventing hospitalisation, symptomatic disease and infection due to both Delta and Alpha variants,” the update said.