Explained: All you need to know about new ‘variant of concern’ Delta Plus

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While India is coming out of the devastating second wave of the coronavirus pandemic, new concerns have cropped up recently. The Delta variant, reportedly the more transmissible strain of Covid-19, is expected to become a ‘dominant lineage' if current trends continue, the World Health Organisation (WHO) warned after it was detected in 85 countries and continues to be detected in more places around the world. This was part of the Covid-19 Weekly Epidemiological Update released by WHO on June 22.

Further, on June 23, the Union Health Ministry stated that around 40 cases of the Delta Plus variant [a sub-lineage of the Delta variant], classified as a variant of concern (VOC), have been detected sporadically in Maharashtra, Kerala and Madhya Pradesh. As reported by Mid-day, so far 21 cases of the new variant have been found across seven districts in Maharashtra, with coastal Ratnagiri topping the list.

Mid-day.com spoke to Dr. Lancelot Pinto, consultant pulmonologist and epidemiologist, P.D Hinduja Hospital about what the Delta Plus variant is, the difference between it and the Delta variant, and what precautionary measures can be taken to avoid exposure to it.

What is the Delta variant of Covid-19?

Delta variant or B.1.617.2 was first described in India in late 2020. It has now been reported in over 70 countries across the world and is the major variant in the United Kingdom at present. It has been reported to be at least 40% more transmissible than the Alpha variant, possibly either due to the avid binding to the ACE2 receptor or enhanced fusion with the receptor. There are indicators that the Delta variant might be associated with increased hospitalisation rates in addition to increased transmissibility.

What is the difference between the Delta variant and Delta Plus variant?

The Delta Plus variant, in addition to having the mutations that the Delta variant has, also has an additional K417N mutation which causes a substitution of an amino acid called lysine with arginine in the spike protein. This mutation is also seen in the Beta variant which was first described in South Africa. This is concerning because the Beta variant in South Africa seemed to evade the protective immunity generated by the Astra vaccine (Covidshield vaccine in India). This is why South Africa chose not to use the vaccine. There is also a suggestion that the Delta Plus variant is not neutralised by the antibody cocktail which is currently been used in the treatment of Covid-19. As the virus proliferates and is transmitted in the community it constantly gains and undergoes new mutations resulting in the formation of variants.

Delta Plus has been named a Variant of Concern (VOC). What does this mean?

A variant is called a variant of concern when there is evidence for an increase in transmissibility (it is more infectious) or it results in more severe disease (more individuals who get infected get hospitalised or die) or shows a significant reduction in neutralisation by the antibodies generated either from natural infection that a person has had in the past or from vaccination, resulting in potentially high rate of reinfections or vaccine breakthrough infections. A variant is also called a variant of concern when the existing diagnostic tests for the virus fail to detect it.

How does one get infected by it?

One gets infected with this variant in the same way one gets infected with the other variants through droplets or through airborne mode of spread suggesting that masking, sanitising and distancing are still likely to be the most effective tools against spread.

How prevalent is it so far? How many cases have been reported?

The Delta Plus variant has been reported in multiple countries across the world. However, the numbers are still small and we do not know whether the mutation (K417N) renders the variant more or less transmissible. There is speculation, however, that this variant is likely to be more transmissible.
What are its symptoms? Are they different from the symptoms noted so far with Covid-19?
For the Delta variant it was suggested that headache, fever and running nose were the three most common symptoms reported, whereas loss of smell, which was the predominant symptom for the alpha variant, did not seem to occur as commonly. For the Delta Plus variant we do not have enough information to know whether the symptoms would be any different.

Which age group is the most vulnerable against this variant?

We don't know which age group would be most vulnerable.

What is the indication so far on its transmissibility? It is said to have stronger binding in receptors of lung cells. What does this mean?

There is some speculation that it is likely to be more transmissible however the numbers are too small yet to be sure.
The Delta variant was found to have a stronger binding to the ACE2 receptor and enhanced fusion with the receptor. This was thought to be one of the reasons because of which it was easily transmissible from one person to another as it bound avidly to the receptors which are present in the nasopharyngeal and lower respiratory tract.

It is also said that it shows potential reduction in monoclonal antibody response. Can you explain this?

Every virus and variant has shown to have certain thresholds for neutralising antibodies to neutralise the virus. Variants that are called escape variants or variants that have escape mutations have mutations that would render them resistant to neutralisation by lower titers of antibodies and would take a higher level or neutralising antibodies to neutralise them.

There is also a possibility that some mutations render a virus resistant completely to the neutralising effects of neutralising antibodies and this might be the case for the Delta Plus variant when it comes to the neutralisation of the virus which occurs with the antibody cocktails that are currently available. This would suggest that there are different proteins in the virus's structure that would need to be targeted with antibodies for neutralising them and the current neutralising antibodies may not adequately neutralise the new variants.

How effective are vaccines against this variant?

Data from the UK suggest that the current vaccines have a lower efficacy against the Delta variant than the alpha variant for symptomatic disease. However, when it comes to hospitalisations and deaths two doses of the Astra vaccine do appear to be effective in preventing hospitalisations to a significant extent and deaths. We do not know if that is true for the Delta Plus variant.

What precautionary measures, apart from the usual Covid-19 protocols, should citizens and governments take?

Since we do not yet know the efficacy of the currently given vaccines against the newer variants such as the Delta Plus variant, the traditional measures of arresting spread such as masking (double masking when indoors, sanitising, distancing) need to be re-emphasised.
Governments also need to be very cautious before completely unlocking society and allowing for the free movement of individuals especially in the context of over-crowding in indoor situations.

(With inputs from PTI)

Also Read: Explained: What to do and what to avoid before and after vaccination