Delta ‘is likely more severe’

WITH a new wave of COVID-19 infections fuelled by the Delta variant striking countries worldwide, disease experts are scrambling to learn whether the latest version of coronavirus is making people, mainly the unvaccinated, sicker than before.

The US Centers for Disease Control and Prevention warned that Delta, first identified in India and now dominant worldwide, is “likely more severe” than earlier variants, according to an internal report made public on Friday.

The agency cited research in Canada, Singapore and Scotland showing that people infected with the Delta variant were more likely to be hospitalised than earlier in the pandemic.

In interviews, disease experts said the three papers suggest a greater risk from the variant, but the study populations are limited and the findings have not yet been reviewed by outside experts.

Doctors treating patients infected with Delta described a more rapid onset of Covid-19 symptoms, and in many regions an overall increase in serious cases.

But the experts said more work was needed to compare outcomes among larger numbers in epidemiologic studies to establish if one variant causes more severe disease than another.

“It’s difficult to pin down increase in severity and population bias,” said Lawrence Young, a virologist at the UK’S Warwick Medical School.

In addition, it was likely that the extraordinary rate of Delta transmission was also contributing to a greater number of severe cases arriving at hospitals, the experts said.

Delta is as contagious as chickenpox and far more contagious than the common cold or flu, according to the CDC report.

Shane Crotty, a virologist at the La Jolla Institute for Immunology in San Diego, said the clearest indication that the variant may cause more severe disease comes from the Scotland study, which found that Delta roughly doubled the risk of hospitalisation.

The majority of hospitalisations and deaths in the US are occurring in people who have not been vaccinated. But there is evidence that the shots are less effective in people with compromised immune systems, including the elderly. For vaccinated, healthy people, the odds are if they contract Covid-19 they will only experience asymptomatic or mild disease, said Dr Gregory Poland, infectious disease expert at the Mayo Clinic.