PARIS – The Delta variant of Covid-19 doubles the risk of hospitalisation compared with the Alpha strain it has supplanted as the dominant one worldwide, researchers reported in The Lancet today.
Only 1.8% of the more than 43,000 cases assessed in comparing the two variants were patients who had been fully vaccinated.
Three-quarters were completely unvaccinated, and 24% had received only one jab of a two-dose vaccine.
“The results from this study therefore primarily tell us about the risk of hospital admission for those who are unvaccinated or partially vaccinated,” said co-lead author Anne Presanis, a senior statistician at University of Cambridge’s MRC Biostatistics Unit.
Researchers analysed healthcare data from 43,338 Covid-19 cases in England from March 29 to May 23, including vaccination status, emergency care, hospital admission and other patient information.
All virus samples underwent whole genome sequencing, the surest way to confirm which variant caused the infection.
Just under 80% of the cases were identified as Alpha, and the rest, Delta.
One in 50 patients was admitted to hospital within 14 days of their first positive test.
After accounting for factors known to affect susceptibility to severe illness, including age, ethnicity and vaccination status, the researchers found that the risk of being admitted to hospital more than doubles with Delta.
‘Excellent protection’
Since these samples were taken, Delta has surged and now accounts for over 98% of new coronavirus cases in Britain, said the authors.
Multiple studies have shown that full vaccination prevents infection with symptoms and hospitalisation, for both Alpha and Delta.
“We already know that vaccination offers excellent protection against Delta,” said Gavin Dabrera, another lead author and a consultant epidemiologist at the National Infection Service, Public Health England.
“It is vital that those who have not received two doses of the vaccine do so as soon as possible.”
An earlier study from Scotland also reported a doubling in hospitalisation risk with Delta over Alpha, suggesting that the former causes more severe disease.
The variant was first reported in India last December, and early studies found it to be up to 50% more transmissible than Alpha, first identified in England in September the same year.
Nearly 4.5 million deaths worldwide have been attributed to Covid-19, though the final tally is likely to be higher once “excess deaths” are calculated over the pandemic period.
In some countries – and some states in the United States – hospitalisation and death rates are the highest they have been since the first cases reported at the beginning of 2020. – AFP, August 28, 2021
