New COVID-19 Variant 'Delta Plus' With 'Higher Transmissibility' Found In US, UK

A new and more transmissible COVID-19 variant has been detected by health officials in the United Kingdom and the United States, sparking concerns over whether it can evade immunity offered by currently available vaccines.

The new variant, called “Delta Plus,” is an offshoot of the B.1.167.2 Delta variant. The Delta sublineage strain was first identified in July and was found to include some new mutations that affect its spike protein, according to BBC.

The AY.4.2 variant has since been detected in the U.S., Denmark, Israel and the U.K. where it was found in 8% of all COVID-19 samples sequenced beginning Sept. 27, according to an Oct. 15 report from the UK Health Security Agency.

In the U.S., the AY variants are listed as variants of concern by the Centers for Disease Control and Prevention. However, it is unclear how many of the sequenced COVID-19 cases in the country are caused by the AY.4.2 variant as the agency does not list it separately from the other AY variants.

It is unclear whether the Delta Plus variant is more infectious, but Dr. Christina Pagel, director of the Clinical Research Unit and professor of operational research at University College London, said it is possible.

"At most AY.4.2 is about 10% more transmissible than Delta—so a bit worse but not that much,” Pagel said in an email to Health.

However, Professor Francois Balloux, director of University College London’s Genetics Institute, said a 10% increase in transmissibility does not explain the recent surge of cases in the U.K.

“Assuming 10% higher transmissibility and a freq of 10% only translates in 1% additional cases per ~5 day viral generation interval,” he said, according to Deadline.

A study led by Germany’s Leibniz Institute for Primate Research, published on Oct. 11, showed that the Delta Plus variant is more efficient in invading lung cells and resisting treatment. The study also found that the offshoot Delta variant particularly resists monoclonal antibodies that help prevent COVID-19 hospitalizations.

However, the same study found that a combination of vaccines developed by Oxford-AstraZeneca and Pfizer-BioNTech could provide a robust protection against both the Delta variant and the offshoot AY.4.2. variant.

“The combination of two vaccines may thus induce a particularly strong immune protection against SARS-CoV-2 variants,” the researchers for the Leibniz Institute said in a press release.