COVID-19: Delta doubles hospital risk vs Alpha variant

TheDeltavariantof the virus that causesCovid-19doublestheriskof hospitalisation compared to theAlphavariantit has supplanted as the dominant strain worldwide, researchers reported Saturday in The Lancet.

Only 1.8 percent of the more than 43,000Covidcases assessed in comparing the two variants were in patients who had been fully vaccinated.

Three-quarters were completely unvaccinated, and 24 percent had only received one jab of a two-dose vaccine.

"The results from this study therefore primarily tell us about theriskofhospitaladmission for those who are unvaccinated or partially vaccinated," said co-lead author Anne Presanis, a Senior Statistician at the University of Cambridge's MRC Biostatistics Unit.

Researchers analysed healthcare data from 43,338COVID-19 cases in England from March 29 to May 23 of this year, including vaccination status, emergency care,hospitaladmission and other patient information.

All virus samples underwent whole genome sequencing, the surest way to confirm whichvarianthad caused the infection.

Just under 80 percent of the cases were identified as theAlphavariant, and the rest wereDelta.

Around one in 50 patients were admitted tohospitalwithin 14 days of their first positiveCOVID-19 test.

After accounting for factors that are known to affect susceptibility to severe illnessincluding age, ethnicity, and vaccination status, the researchers found theriskof being admitted tohospitalwas more than doubled with theDeltavariant.

'Excellent protection'

Since these samples were taken,Deltahas surged and now accounts for over 98 percent of newCovid-19 cases in Britain, the authors said.

Multiple studies have shown that full vaccination prevents infection with symptoms and hospitalisation, for bothAlphaandDeltavariants.

"We already know that vaccination offers excellent protection againstDelta," 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 vaccine do so as soon as possible."

An earlier study from Scotland also reported a doubling in hospitalisationriskwithDeltaoverAlpha, suggesting thatDeltacauses more severe disease.

TheDeltavariantwas first reported in India in December 2020 and early studies found it to be up to 50 percent more transmissible than theAlphavariant, which was first identified in England in September last year.

Nearly 4.5 million deaths worldwide have been attributed toCovid-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.