What is the Delta variant and now the Delta plus?

The Indian government reported last June that a new SARS-CoV-2 Delta coronavirus mutation had already been detected. This mutation changes Spike protein, the key to the virus entering the cells infected with it.

This new version (also known as AY.1 or B.1.617.2.1) has been identified as Delta Plus;  in India, 48 individuals were infected with the Delta variant because of this additional mutation (out of a total of over 45,000 samples tested). Due to increasing transmissibility, Delta Plus is considered a “variant of concern” by the Indian Ministry of Health.

How does the Delta variant differ, and what is known about its ability to evade the vaccine’s immunity?

According to the World Health Organization, the SARS-CoV-2 Delta version was initially detected in India and is now the world’s most important variant according to the World Health Organization. In the violent second wave which struck India last spring it played a significant role.
Several studies have shown that the Delta variant can replicate and spread faster than other versions and that receptors on the surface of lung cells are supposed to bind more closely.
Indian researchers found that three-quarters of the outbreaks in the city of Delhi were from vaccinated individuals. Still, this study was not yet reviewed (8 percent of these infections were reportedly due to the Kappa – or B.1.617.1 – variant, and 76 percent to the Delta – or B.1.617.2 – variant, with the remainder linked to other B.1 variants).

In Europe, in March 2021, the new Delta variant mutation was first found.
The new mutant, a concern for the authorities, was also found in June for patients with Covid-19. Some Indian scientists fear that it may cause new infections.
However, the mutation of the Delta Plus variant in the Spike protein is not a new one. The Beta Variant, initially found in South Africa, has already been described as “K417N.” It has been shown that the Beta variety with this mutation can avoid vaccinated antibodies of AstraZeneca. This raises the concern that several Delta Plus vaccines may not be as effective as other variants.

The Delta Plus variant, according to the Indian Ministry of Health, may be capable of escaping immunity and of withstanding the effects of anti covid 19 anti-compound monoclonal antibody therapies.

It is located on the Spike protein, a significant component of the virus concerning this mutation. Earlier mutations affected the Spike protein receptor-binding domain, which allows the virus to bind to receptors at the cell’s surface.

Delta mutations can already help to some extent evade the immune system. Some vaccines showed somewhat less efficacy and have reduced the level of protection with a single dose. However, the second dose of vaccine continued to produce enough antibodies to prevent symptomatic infections and severe forms of the illness. Keep in mind that most Covid 19 vaccines do not offer absolute immunity but limit the seriousness of the disease.

British researchers have shown that one dose of Pfizer’s RNA vaccine is 33% Delta-effective and 88% effective after a second injection. With AstraZeneca, the efficacy of the first dose and the second dose is 33%. The effectiveness is 60%.
Similar efficacy reductions may affect the Delta Plus variant, but insufficient data may affect the certainty. The efficacy of current vaccinations against this new variant is being tested in India.

Note that the Delta Plus variant is still not widespread and has not yet been classified as a variant of concern by the World Health Organization.

The development of variants with increased transmissibility and the ability to avoid antibodies threatens pandemic success. Moreover, countries with the lowest levels of vaccination are at risk of new outbreaks.

These new mutations do not mean that it is necessary to take further measures to address the epidemic. Instead, it is essential to continue to increase the number of individuals vaccinated, comply with behaviour recommendations during an outbreak and improve genomic surveillance so that the evolution of SARS-CoV-2 is monitored as closely as possible.