Race between covid-19 vaccines and delta variant plays out in UK

The other message is one of caution. Epidemiologists say the U.K.’s experience shows how easily the variant can spread even within populations where vaccine uptake is high. That underscores the risk of further outbreaks of Covid-19 in the U.S. and other advanced economies, as well as the urgency of widening and accelerating vaccination programs.

“The Delta variant is currently the greatest threat in the U.S. to our attempt to eliminate Covid-19," Anthony Fauci, President Biden’s chief medical adviser, said Tuesday.

Delta, also known as B.1.617.2, was first identified in the U.K. in March and has since spread to become the dominant version of the coronavirus in the country, with more than 75,000 cases confirmed by genetic analysis. A planned lifting of all remaining public-health restrictions this week was postponed until mid-July in response to the variant’s surge.

British scientists estimate the variant is 40% to 80% more transmissible than the Alpha variant, the dominant variant in multiple countries, which is itself more transmissible than the original virus that emerged from China in late 2019.

Delta was first spotted in India, where it propelled a deadly wave of infections this spring. It has now been detected in more than 70 countries. U.S. Centers for Disease Control and Prevention data on Tuesday showed the proportion of Delta virus samples in the U.S. hit 20.6% in the two weeks ending June 19, up from 9.9% the previous two weeks. A study published this week estimated it could account for 50% of cases as soon as next month.

The U.K.’s experience shows how fast Delta can take hold. The U.K. seven-day average of new Covid-19 cases was around 2,000 in early May. Now, daily cases are five times that number and rising, and Delta, undetected until March, accounts for 99% of viral samples subject to genetic analysis, according to England’s public-health agency.

The outbreak has accelerated despite widespread U.K. vaccination. Almost 60% of adults are fully vaccinated there and another 22% are awaiting their second dose.

“It’s a much more difficult virus to control," said Martin Hibberd, professor of emerging infectious diseases at the London School of Hygiene and Tropical Medicine, with regards to the Delta variant.

Still, U.K. data show vaccines are having a powerful effect. Data published by Public Health England show the variant is primarily spreading among younger age groups, who have only recently been made eligible for vaccination, in a government drive to extend immunity before a full reopening now slated for July 19.

Under 40s account for three-quarters of Delta cases, according to the data. Over 60s, around 90% of whom are fully vaccinated, make up only 4% of cases.

The vaccine effect is even more pronounced in hospitalizations. In previous waves of infection, between 10% and 15% of all cases would end up in hospital with severe illness, said Linda Bauld, professor of public health at the University of Edinburgh. Now, with vaccines, the proportion is closer to 4%, she said.

Doctors on the front line say they are seeing far fewer elderly people needing hospital treatment compared with similar stages of past waves of infection, as well as fewer patients overall. Data from the National Health Service in England shows over 65s accounted for less than one-third of 3,000 Covid-19 hospital admissions in the six weeks through June 6. Before the vaccine rollout began in December, over 65s routinely made up more than two-thirds of admissions.

“It is the younger, unvaccinated people that are getting sick," said Nathan Spence, a physician who works on a Covid-19 ward in Oxford. Doctors say they are sometimes seeing unusual symptoms with Delta cases, such as runny noses and congestion, rather than the classic Covid-19 symptoms of high fever and loss of taste or smell.

David Strain, a physician and medical school instructor in Exeter, said there are eight people in hospital with Covid-19 in his district, compared with the 50 to 60 he would have expected in the absence of vaccines. The bigger pressure on staff is coming from the backlog of other illnesses that went untreated during the pandemic, he said.

“I don’t see us getting back to a position where we’ve got ICUs [intensive-care units] being overwhelmed again," he said. “The vaccine is doing a tremendous job at breaking the chain between infection and ICU."

Public Health England had logged just 73 deaths from Delta as of June 14. Over the last seven days, 13 deaths from Covid-19 have been reported daily on average. Disease experts anticipate deaths will increase in the coming weeks as Delta reaches more people, but the effectiveness of vaccines at preventing severe illness is expected to keep average fatalities well below the 1,200-a-day level reached at the height of the last wave in January.

Two additional lessons on Delta from the U.K. are that two doses of vaccine provide much better protection than one against the variant, and that some vulnerable people are likely to still succumb to the virus even after two doses, because the shots aren’t 100% effective. Of those 73 deaths associated with Delta, 26 were among people who had been fully vaccinated. Scientists say those deaths are likely concentrated among the old and frail groups that are prioritized for vaccination because they are at much greater risk from Covid-19.

Deaths would likely have been considerably higher without the shots, said Irene Petersen, professor of epidemiology and health informatics at University College London. “The vaccines are working," she said.

This story has been published from a wire agency feed without modifications to the text