









































                                                                                                                         2021, Vol. 1 (S4) 6-8 
 https://doi.org/10.47488/dhrp.v1iS4.20 

 
http://dhrproceedings.org 6 © DHR Health Institute for Research and Development 
 

 

COMMENTARY 

An Evolving Public Health Crisis Caused by the 
Rapid Spread of the SARS-CoV-2 Delta Variant 
The Protective Effect of Vaccination 
Sohail Rao, MD, MA, DPhil1, 2 and Manish Singh, MD, FACS3 

 1 Executive Vice President, DHR Health, 5501 S. McColl Road, Edinburg, Texas 78539 and President 
& Chief Executive Officer, DHR Health Institute for Research & Development, 5323 S. McColl Road, 
Edinburg, Texas 78539.  
ORCID: https://orcid.org/0000-0001-5027-9992  
2 Correspondence should be addressed to: Sohail Rao, MD, MA, DPhil., DHR Health Institute for 
Research & Development, 5323 S. McColl Road, Edinburg, Texas 78539. Tel: (956) 362-2387. E-mail: 
s.rao@dhr-rgv.com  
3 Chief Executive Officer, DHR Health, 5501 S. McColl Road, Edinburg Tx 78539 and DHR Health 
Bariatric and Metabolic Institute, 500 Raphael Drive, Edinburg, TX 78539  
ORCID: Manish Singh: https://orcid.org/0000-0003-4146-3282  
 
Received 06/24/2021 
Accepted for publication 06/29/2021 
Published 06/29/2021 

Keywords:  COVID-19; SARS-CoV-2; Delta Virus; Vaccination

SARS-CoV-2 virus has already infected over 181 million 
people worldwide and has resulted in the death of over 3.9 
million (1). In the United States alone, over 33 million people 
have been infected with SARS-CoV-2 which has resulted in 
the death of over 600,000 (1). The rapid development and 
deployment of several effective vaccines against the virus has 
lowered but not eliminated the threat to imminent public 
health crisis. Further compounding this challenge is the 
continued vaccine hesitancy and the non-availability of 
vaccines globally (2).  

The notable competence of viruses to adapt to new hosts and 
environments is largely conditional on their capacity to 
generate de novo multiplicity in a relatively short period of 
time (3). It is therefore predictable that the rates of 
spontaneous mutation would vary among viruses. 
Additionally, RNA viruses mutate at a much faster rate than 
DNA viruses and the size of the genome is conversely related 
to the rate of mutation. It is important to note that selective 
host and environmental pressures (such as the use of anti-viral 
agents, etc.) can impact the rate of viral mutation thus 
accelerating the generation of new and more contagious 
variants (4).SARS-CoV-2 is an RNA virus and under optimal 
conditions it has a very high rate of mutation. The Centers for 
Disease Control and Prevention has developed a variant 

classification scheme that defines three classes of SARS-CoV-
2 variants (5).  To date, none of the SARS-CoV-2 variants has 
been identified as a Variant of High Consequence. On the 
contrary, seven Variant of Interest and six Variant of Concern 
have been identified (5). Most of the variants have mutations 
in the gene encoding SARS-CoV-2 spike protein, which 
affects their transmissibility; disease severity; reduced 
neutralization by antibodies generated against previous 
infection or vaccination; reduced efficacy of available 
treatment; and potential diagnostic impact.  

One of the variants of SARS-CoV-2 that is a Variant of 
Concern and is rapidly spreading in the US is of the lineage 
B.1.617.2 (Figure 1).  Erroneously labelled as the “Indian 
Variant”, this mutant was first reported in India, but its true 
origin remains unknown (6). Renamed as the Delta variant by 
the World Health Organization, it is believed to be the cause 
of the devastating second wave of the pandemic in India, 
which crippled its healthcare infrastructure resulting in 
thousands of deaths everyday (7, 8). Also identified as the 
Variant of Global Concern, B.1.717.2 has been detected in 
more than 40 countries and is the dominant variant in the 
United Kingdom (9). The Delta variant has mutations in the 
gene encoding the spike protein causing substitutions T478K, 
P681R and 452R (10). Collectively, these mutations increase 

https://orcid.org/0000-0001-5027-9992
mailto:s.rao@dhr-rgv.com
https://orcid.org/0000-0003-4146-3282


DHRP, 2021, Vol. 1 (S4) 6-8  The Protective Effect of Vaccination 

 
http://dhrproceedings.org 7 © DHR Health Institute for Research and Development 
 

viral transmissibility and alter the neutralizing ability of 
monoclonal antibodies and convalescent plasma from 
recovered patients with COVID-19. 

Figure 1: The percentage of Delta variants in patients 
diagnosed with SARS-CoV-2 in the US. 

A recent study published in the journal Lancet suggested that 
the risk of hospitalization doubled in those infected with the 
Delta variant of SARS-CoV-2 as compared to the Alpha 
variant (11). Additionally, this study also underscored the 
protective effect of vaccination against infection with this 
variant. Pfizer-BioNTech vaccine was 88% effective against 
symptomatic disease from the B.1.617.2 variant two weeks 
after the second dose. Two doses of the AstraZeneca vaccine 
were 60% effective against symptomatic disease from the 
B.1.617.2 variant. It is notable that both vaccines were only 
33% effective against symptomatic disease from Delta 
variant, three weeks after the first dose (11).  

Given these observations, it can be envisaged that as in the 
past, SARS-CoV-2 virus will continue to mutate, and it is 
likely that future variants will be as infectious if not more than 
the currently circulating mutants. Therefore, it is imperative 
that we intensify our efforts to sequence all positive cases of 
COVID-19 to ascertain the extent of SARS-CoV-2 mutations. 
Lastly, given the protective effect of currently available 
vaccines, it is highly recommended that all qualified 
individuals 12 years and above get vaccinated to protect 
themselves from symptomatic disease resulting from exposure 
to either the wild-type and/or the variants of SARS-CoV-2 
virus. Incentivizing qualified individuals should be seriously 
considered particularly in regions of relatively lower 
vaccination rates and younger adults who are seemingly 
hesitant to get vaccinated. Needless to say, a robust and 
sustained public health education program is essential to 
address existing crisis and to mitigate such challenges in the 
future. 

 

Diclosures 

SR declares no conflicts of interest.  

MS declares no conflicts of interest. 

Funding 

The project is funded by a Seed Grant from the DHR Health 
Institute for Research & Development 

References 

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https://www.theguardian.com/world/2021/jun/11/delta-variant-is-linked-to-90-of-covid-cases-in-uk


DHRP, 2021, Vol. 1 (S4) 6-8  The Protective Effect of Vaccination 

 
http://dhrproceedings.org 8 © DHR Health Institute for Research and Development 

10. "Expert reaction to VUI-21APR-02/B.1.617.2 being 
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https://doi.org/10.1016/S0140-6736(21)01358-1 

 

 

https://doi.org/10.1016/S0140-6736(21)01358-1

