Photo/Illutration The Delta variant of the novel coronavirus (Provided by the National Institute of Infectious Diseases)

Researchers in Japan are calling for new vaccines to be developed to protect the public from breakthrough variants of the novel coronavirus, such as the highly contagious Delta strain that comes with a combination of mutations.

A team led by Hisashi Arase, a professor of immunochemistry at Osaka University’s Research Institute for Microbial Diseases, issued a paper on its research findings that can be viewed by accessing (https://www.biorxiv.org/content/10.1101/2021.08.22.457114v1.full#ref-44).

It said mRNA-based vaccines, such as the one developed by Pfizer Inc., provide effective protection against most common COVID-19 variants, but “identifying likely breakthrough variants is critical for future vaccine development.”

The group ascertained that when four specific mutations are added to the Delta variant, the effectiveness of current vaccines could be greatly weakened.

The members first analyzed blood samples taken from 20 people who had received Pfizer vaccine jabs to gauge the ability of their immune systems to fight off infection. They confirmed that the vaccine is effective in preventing infection through the Delta variant.

But the researchers discovered that the vaccine’s effectiveness against the Delta variant has decreased in comparison with its effectiveness against other existing strains.

They also found that some antibodies created by the vaccine do not attach themselves to the Delta variant.

A key mechanism in preventing infection requires antibodies created by a vaccine to attach to the protein of a virus. If this does not happen, the effectiveness of the antibodies noticeably drops.

They also studied changes in the effectiveness of antibodies when the Delta variant further mutates. To accomplish this, they created an artificial non-pathogenic virus for laboratory use and chose four mutations that potentially derive from the Delta variant, based on mutations already detected.

When a mutation was added to the Delta variant one at a time, the effectiveness to prevent infection remained intact.

But when all four mutations were added at once, many antibodies did not attach to the virus, meaning effectiveness was substantially reduced.

Team members found that creating an antibody based on the Delta variant, rather than on conventional variants, can help protect against the Delta variant with four mutations added.

A variant that contains two of the four mutations has already been found, the researchers said.

The chances of the virus mutating rises exponentially with increased rates of infections, they added.

“It is clearly necessary to find a new strategy to develop a new vaccine,” Arase said.