After being reported in 85 countries and continuing to be detected in more places around the world, the WHO has warned that the Delta variant, a significantly more transmissible strain of Covid-19, is expected to become a “dominant lineage” if current trends continue.
According to the World Health Organization’s (WHO) Covid-19 Weekly Epidemiological Update, Alpha has been reported in 170 countries, territories, or areas worldwide, Beta in 119 countries, Gamma in 71 countries, and Delta in 85 countries.
“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 update said.
WHO said the four current ‘Variants of Concern’ being monitored closely – Alpha, Beta, Gamma and Delta – are widespread and have been detected in all WHO regions.
“The Delta variant is significantly more transmissible than Alpha variant, and is expected to become a dominant lineage if current trends continue.”
According to the update, India had the highest number of new Covid-19 cases, 441,976, in the previous week (June 14-20, 2021), a 30% decrease from the previous week. India had the highest number of new deaths reported (16,329 new deaths; 1.2 new deaths per 100,000; a 31 per cent decrease).
Over 600,000 new cases and over 19,000 new deaths were reported in the South-East Asia Region this week, down 21% and 26% respectively from the previous week.
“Decreasing trends in weekly case and death incidence in the Region are predominantly associated with decreases reported in India,” the update said.
WHO noted that since the last detailed update on June 8, new evidence has been published on the phenotypic characteristics of the Delta variant. “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.
Furthermore, when compared to the Alpha variant, a study in Japan found that “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 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,” the update said.
The update also mentioned two studies that showed that the Pfizer BioNTech-Comirnaty and AstraZeneca-Vaxzevria vaccines were effective against the Delta variant. In the United Kingdom, one study looked at the effectiveness of these vaccines against severe disease (hospitalisation) caused by Delta in people over the age of 16.
Over 14 days after the second dose, vaccine effectiveness against hospitalisation due to Delta and Alpha variants was estimated to be 96 percent and 95 percent for Pfizer BioNTech-Comirnaty and 92 percent and 86 percent for AstraZeneca-Vaxzevria, respectively.
“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.
