Can COVID-19 Vaccines Combat The Newly Emerged Delta Variant?

Introduction

With the pandemic still rampant across the country, it does appear to us that it may take a long time due to emerging multiples of virus variants. Some of these variants are silent mutations and are not effective, while the others, like the latest COVID Delta variant B.1.617.2, are increasing the severity of the COVID-19 spread in India. Scientists say that the sudden surge in COVID-19 cases is because of the additional mutations in B.1.617.2 lineage, leading to a Delta plus variant (AY.1).

The COVID Delta variant was first detected in India and is now a Variant of Concern (VoC) for about 85 countries. The Delta variant is the dominant strain in the UK, comprising 91% of the cases. The Delta plus variant is present in 12 countries and so far 50 cases have been identified in 12 Indian states. According to the statement released by the Union Health Ministry, the COVID Delta plus variant has characteristics like increased transmissibility, stronger binding to lung receptors and decreased monoclonal antibody production.  

Although there is a substantial decline in effectiveness, the approved COVID-19 vaccines remain effective against infection and hospitalization due to the Delta variant.

Dr. M.G. Kartheeka, MBBS, MD(Pediatrics)

Delta Variant and Vaccine Concern

All the experts worldwide are confident that most of the existing vaccines can deal with the new COVID Delta variant. Although it is 60% more transmissible than the alpha variant, they have observed only around 50 cases of the new variant in the last two months. So, experts opine that there is no need to panic but suggest scaling up vaccination drives across the countries as it is the only practical way to combat the Coronavirus. 

Scientists are concerned about the effects because of the mutation on the spike protein of the Delta plus variant. In India, the spread of the COVID Delta variant infection is localised and sporadic. However, it mainly spreads to the unvaccinated populations and it affects the most vulnerable individuals who suffer severe illness and have chronic infections. 

Most of the vaccines developed are active against the alpha strand of the COVID-19 virus. Therefore, the COVID-19 vaccine’s efficacy is a concern for the Delta variant, which has led to the public being apprehensive about getting vaccinated. The effectiveness of vaccines, which was up to 94% for the alpha variants, has been reduced to about 60% – 70% for Delta variants. Moreover, the clinical trials of the Novavax vaccine and Sputnik V vaccine are still in process for the Delta variant.

COVID-19 vaccines give you protection against serious illness caused by the original strain of the virus and the viruses variants that cause COVID-19, many developed across the world are bringing in seasonal flu and covid vaccinations to continue building herd immunity.

Dr. Ashish Bajaj, MBBS, MD in Clinical Pharmacology and Toxicology

How Effective are the Existing Vaccines Against the Delta Variant?

The Delta variant is more resistant to existing vaccines than other COVID-19 variants. It is estimated that the Delta variant may present mild illness in people who received both doses of the COVID-19 vaccine. According to the research data published in Lancet, two weeks after the second dose, the Oxford/AstraZeneca vaccine – Covishield in India – is showing 60% efficacy against the Delta type while the Pfizer/BioNTech seems to be around 88%.  

The Pfizer and AstraZeneca vaccines were only 33% effective three weeks after the first dose against the Delta variant. The Covaxin of Bharat BioTech, Sputnik V and Novavax vaccines were also reported to be effective against the Delta variant but it is not known to what extent. Other studies by Public Health England (PHE) suggest that the Pfizer/BioNtech vaccine has shown 94% effectiveness after hospital administration of one dose and 96% after the second dose. The Covishield vaccine efficacy was 71% and 92%, respectively.  

Why is it Hard to Decide the Most Influential Vaccine?

Despite the various COVID-19 vaccines in the market, it takes time to decide the best among them. Efficacy is usually denoted as the percentage reduction of the disease in people who received the vaccination, whereas the effectiveness can be compared after administering different vaccines to the same populations. For instance, Pfizer and AstraZeneca have similar effectiveness and they reliably prevent COVID-19 symptoms, hospitalization and death even after a single dose. 

Regardless of the statistical figures, the studies and the clinical trials are ongoing to determine the existing COVID-19 vaccine’s efficacy against the COVID Delta variant. Researchers at the Indian Council of Medical Research (ICMR) have cultured the COVID Delta variant and are now testing in the laboratory to check the performance of the COVID-19 vaccines against the Delta variant. Though researchers test a range of doses, schedules and combinations of vaccines, it is sometimes difficult to conclude how long the vaccine-mediated immunity will last. 

It is not simply possible to compare the results alone. In order to rank the vaccines, one must consider their reported effectiveness, supplies and logistics costs, the durability of the protection they offer and their ability to resist emerging viral variants. Nevertheless, the best vaccine is the one you can get immediately. 

Conclusion

The global pandemic is emerging with distinct viral variants of concern. Mutations that alter immunogenicity, virulence and pathogenicity can lead to the new strain. As new strains emerge because of coronavirus mutations, the only reliable measure to stay safe is to get vaccinated and follow COVID-appropriate behavior.

There have been cases in India wherein fully vaccinated individuals were affected by the COVID-19 Delta variant. But the majority of these individuals were able to make full recovery. Therefore, vaccination protects to an extent. 

Getting both shots of the vaccine and maintaining social distancing not only ensures your safety but prevents the creation of new strains through mutation as well.  

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