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Delta and Delta Plus Variant of COVID-19: Key things to know

Are covid-19 vaccines effective against Delta and Delta Plus Variants


The leading cause for rapid transmission and depletion of oxygen levels in patients during the second wave of COVID-19 in India was due to the Delta Variant of COVID-19. The Centers for Disease Control and Prevention (CDC) has classified COVID-19 variants into Variants of Interest, Variants of Concern, and Variants of High Consequence. This classification is being done depending upon the evidence on how rapid does the virus transmit and how serious cases it can cause leading to decreased efficacy of vaccine or any other medicine, increased hospitalization including disruptive diagnostic tests. According to CDC, at present, there are no SARS-CoV-2 variants that can be classified as a variant of high consequence.

The B.1.617.2 variant of SARS-CoV-2 is known as the Delta Variant. The term Delta is given by WHO. The Delta variant is classified as a Variant of Concern. Variant comes into the picture when a virus mutates.

It is interesting to understand how viruses mutate. The SARS-CoV-2 is an RNA virus and is made of about 30,000 base pairs of amino acids. Any change or alteration in these base pairs can lead to mutation, and the virus changes its shape and behavior. The delta variant is thus a product of multiple mutations in the spike protein. There are four mutations that play an important role in the delta variant.

  1. L452R mutation
  2. P681R mutation
  3. D614G mutation
  4. T478K mutation

Now, recently it has been found that the Delta Variant has undergone mutation, and now it is known as the Delta Plus Variant. So, what are these Delta and Delta Plus Variant? Will the present vaccine work on these variants? How can we protect ourselves from these variants? This blog has tried to address every corner of the COVID variant that will create awareness among people.

What is Delta variant?

The Delta variant (B.1.617.2) of the SARS-CoV-2 virus has spread rampantly across the globe around 92 countries. It originated from India. Researchers believe that the Delta variant is 40-60% more contagious or transmissible than the Alpha variant (U.K./B.1.1.7) and from the original coronavirus strain of 2019. The delta variant can have multiple mutations leading to the rapid transmission of the virus, which can create more severe COVID waves.

In England, as of June 14, there were 33,630 cases of delta variants in a week. In India, the delta variant dominated the entire second wave, which hit India from the second week of February and was at its peak during May 2021. The delta variant infection resulted in a severe decrease in oxygen level in patients, creating havoc in the country.

What is Delta plus variant?

The Delta plus variant is a part of the existing Delta variant with the addition of K417N mutation in its spike protein. The variant is designated as B.1.617.2.1 and is also called as AY.01 variant. It is considered to be the most dangerous variant of SARS-CoV-2. The first sequence of Delta Plus Variant was discovered in Europe in March 2021. Although despite the Delta variant’s high frequency, its transmission in India has been quite limited. The Delta plus variant is not yet declared a “Variant of Concern” in India, and it is still a “Variant of Interest.” The new variant is being monitored closely by healthcare authorities. The variant is dangerous because it is also affecting people who have been vaccinated for COVID-19. However, there is yet no evidence to prove that the Delta plus variant is highly transmissible. Twenty-one cases of the Delta Plus variant have been registered in India as of June 21, 2021 of which 4 people have succumbed despite being vaccinated.

In an article published by India Today, according to Professor Shahid Jameel, who happens to be one of India’s top virologists and a former member of the INSACOG, “ the Delta Plus variant may be capable of evading immunities that people developed from vaccination well as natural immunity after recovering from COVID. This is because the Delta plus variant not only has all the symptoms that the original Delta variant had, but also carries symptoms from its partner Beta variant (K417N mutation)”.

Are vaccines effective against Delta and Delta Plus?

Laboratory tests by scientists have shown the Delta Variant to have stronger resistance to vaccines than other variants and are contagious. There has been published in a reputed journal which mentioned that the antibody levels in people who took certain mRNA vaccines were six times lower in the presence of the Delta variant when compared to the antibody levels against the original COVID-19 strain for which the vaccine was made.

However, the real-world observations and data will differ and play a significant role in determining the vaccine's effectiveness against delta variants. Public Health England published data to show that certain mRNA vaccine prevents 96% of hospitalization caused by Delta variant. The Adenovirus Vaccine has also revealed 60% efficacy against the delta variant.

Now coming to Delta Plus variant, scientist says that the delta plus variant is very dangerous variant as it transmits faster. However, there is little knowledge about its severity or resistance to antibodies. Some reports claim that the Delta plus (AY.1) is resistant to monoclonal antibodies cocktail, but more research is required in this area. Multiple studies are ongoing in India and globally to test the effectiveness of vaccines against the Delta plus Covid-19 mutation.

According to Dr. Balram Bhargava, the director-general of the Indian Council of Medical Research, “the Delta Plus variant has recently been cultured and it is being examined whether the vaccines are effective against this variant.”

Steps to take care and prevent transmission of Delta and Delta Plus variant of COVID-19

  • Move out of your house only when it is necessary
  • Wear a Face mask when you are moving out of your house.
  • Wash your hands properly with sanitizer and soap before leaving and entering house.
  • Take vaccine. Do not miss your vaccination dose. The delta plus variant may have shown to dominate vaccines in laboratory, but we still do not know how it will behave if its affects to large population. So, take vaccine to keep yourself and your family safe.
  • Maintain Social Distancing. Do not touch your eyes, nose, and mouth without washing your hands.
  • If you have fever, cough, breathing difficulty or any COVID-19 symptom, then isolate yourself from your family and report to a doctor immediately.
  • Headache, sore throat, and runny nose are the major symptoms of the delta variant. So, keep an observation for such symptom.


  1. Here's the Difference Between Delta Variant and Delta Plus Variant of COVID-19. Accessed at
  2. Explained: What is the Delta variant of Covid, and why it is a concern? Accessed at
  3. SARS-CoV-2 Variant Classifications and Definitions. Accessed at
  4. What We Know About the Dangerous COVID B.1.617.2 (Delta) Variant, Chas Danner and Paola Rosa-Aquino. Accessed at
  5. Covid-19 Delta variant cases jump by 33,630 in one week in UK, now make up 99% of country’s cases. Accessed at
  6. Delta Plus variant may defeat vaccines, antibodies and infection immunity, warns Prof Jameel. Accessed at
  7. Delta Plus: Key things to know about new coronavirus variant in India. Accessed at
  8. Covid-19: How vaccines work against the Delta variant. Accessed at
  9. How effective are Covishield and Covaxin against Delta Plus? Report in 7-10 days. Accessed at
  10. Delta variant more contagious, resistant to vaccines than other COVID-19 variants: Here's all we know. Accessed at

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