Why a New Vaccine for the Delta COVID Variant May Be Needed

Governments should consider offering another COVID vaccine specifically tailored to the Delta variant, according to a U.K. government advisor and Delta researcher.

The guidance comes after a new study indicated that the Delta variant was eight times less sensitive to the antibodies that vaccines provide to people compared to an earlier version of COVID from April 2020, in a lab environment.

This means it would take more antibodies from a vaccinated person to block Delta than to block this earlier version of the virus.

According to an early manuscript of the study available online, it also found that Delta was resistant to antibodies from people who had had COVID before.

It found that Delta was 5.7 times less sensitive to antibodies produced by recovered patients than the April 2020 version of COVID, referred to as a "wild type (WT) Wuhan-1" variant.

"We should seriously consider Delta-specific vaccines," said professor Ravi Gupta, professor of clinical microbiology at Cambridge University, member of the U.K. government's New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) virus advisory group, and lead author of the study. "The infectivity enhancement likely explains a lot of the vaccine breakthrough that we see."

Indeed, breakthrough cases have captured numerous headlines this year amid reports of people getting infected with COVID despite being fully vaccinated.

Breakthrough cases are expected with any vaccine, though some COVID variants are thought to pose extra resistance to immunity compared to others.

To investigate Delta's antibody resistance Gupta and the team used blood samples from people who had previously been infected with COVID or who had been vaccinated with the Pfizer or the AstraZeneca shot.

As well as Delta's observed vaccine resistance, the speed at which it spreads through communities is another advantage this variant has.

The study also indicated that Delta was able to replicate more efficiently in human airways compared to the Alpha variant, another COVID mutation first discovered in the U.K. in September 2020. To investigate this, the team grew artificial organs to study what happens when Delta gets in the respiratory tract.

They found the virus was more efficient at breaking into cells compared with other variants and was also better able to replicate.

Gupta told Newsweek the study explains why Delta has managed to spread so rapidly in countries such as the U.S., the U.K., and particularly India, where the variant overtook Alpha. "Our findings on replication speed and partial immune evasion explain this," he said.

"I think the enhanced infectivity and virus production is concerning as it shows this virus has considerable opportunity to become more infectious."

The study also looked at 130 healthcare workers in India who were infected with COVID during a period in which mixed variants were spreading. It found that the Oxford-AstraZeneca vaccine was less effective against Delta than it was against other variants.

It concludes that infection-control measures will be needed to push back Delta even in the post-vaccination era. Gupta said this could mean higher-protection masks in some settings, social distancing measures, and booster shots in the absence of a Delta-specific vaccine.

Dr. Edward Hutchinson, senior lecturer at the Center for Virus Research at the University of Glasgow, in Scotland, who was not involved in the study, told Newsweek that the work is "consistent with a lot of other studies" and added: "It is becoming clear that current vaccines are less effective at slowing the spread of Delta because it can still get a 'foot in the door' and spread with mild symptoms or no symptoms at all."

But, he added, providing booster shots to adults in wealthy countries would not prevent the spread of Delta elsewhere in the world, meaning there would still be a risk of new variants emerging.

He said: "By prioritizing boosters for the wealthy, we compromise global vaccination, this will both a moral and a practical failing—the virus will continue to thrive and keep coming at us until it is brought under control everywhere."

Professor Anurag Agrawal from the CSIR Institute of Genomics and Integrative Biology in India and a joint author on the study said in a Cambridge University press release that the infection of vaccinated healthcare workers with Delta "is a significant problem" and added: "We urgently need to consider ways of boosting vaccine responses against variants among healthcare workers."

The study, SARS-CoV-2 B.1.617.2 Delta variant replication and immune evasion, was published in the journal Nature on September 6.

COVID vaccine
A nurse holds a COVID vaccine vial at a community center in Bowie, Maryland, in March 2021. A scientist has said governments should consider a Delta variant-specific vaccine. Win McNamee/Getty