Global evolution of SARS-CoV-2 Delta variant: is an engineer frivolous toward stemming the global pandemic?

by Eng. (Prof.) Mahesh Jayaweera

What is SARS-Cov-2 Delta variant?

SARS-CoV-2 Delta variant (B.1.617.2) is a mutation of the original SARS-Cov-2 (B.1) first identified from China. This Delta variant has been first identified in India, and as of today, one of its sub-lineages called Delta plus (B.1.617.2.1), another mutated version, became virulent in the UK. One must remember that this Delta variant keeps changing with new mutations over time, and often, the successor could be more threatening and devastating. The World Health Organization (WHO) has declared the Delta variant to be a variant of global concern, as it brings about more casualties than other variants. "As of July 2021, the Delta has been detected in at least 98 countries and is spreading quickly in countries with low and high vaccination coverage," said Dr. Maria Van Kerkhove, Technical Lead, WHO. Adding to the same assertion, "no country is out of the woods yet," said Dr. Tedros Adhanom Gebreyesus, WHO's Head.

Why is Delta variant so threatening?

Epidemiologically, from the hindsight of the rapid emergence of different variants, the Center for Disease Control and Prevention (CDC), the USA, uses three traits to differentiate chimeric variants: viral transmissibility, disease virulence, severity or fatality, and pre-symptomatic or asymptomatic disease transmission. Viral transmissibility is expressed by the basic reproduction number (R0), disease severity by Infection fatality ratio (IFR), and disease transmission by the percentage of infections that are asymptomatic or pre-symptomatic (PI).

R0 is the average number of infected contacts per infected individual. A value of R0 larger than one at a population level means that a virus will continue its propagation among susceptible hosts if no environmental changes or external influences intervene. An R0 value lower than one means that the virus is doomed to extinction at the epidemiological level under those specific circumstances. IFR represents the number of individuals who die of the disease among all infected individuals (symptomatic and asymptomatic). This parameter is not necessarily equivalent to the number of reported deaths per reported cases because many cases and deaths are never confirmed to be the COVID-19, and there is a lag in time between when people are infected and when they die. This parameter also reflects the existing standard of care, which may vary by location and may be affected by the introduction of new therapeutics. PI that is attributed to asymptomatic or pre-symptomatic cases measures the percentage of persons infected with SARS-CoV-2, but never show symptoms of disease or show up symptoms rather late. The CDC has figured out the threatening nature of the Delta variant (B.1.617.2) compared with the original lineage of SARS-Cov-2 (B.1) and manifested in Table 1.

Such conjectures lead us to a pressing question that is so alarmingly awful. The question is, where will we be within another one year if at all, the herd immunity by mass vaccination programs would not be effective or new variants of global concern would significantly evade immune responses? One can argue that this set of conjectures is just a bristling array of implausibilities or a total fallacy that could stand first in line for opprobrium among unwashed masses. In the event of such a bizarre situation close at hand, engineers need to voice against such a wall of silence, as engineers are believed to be a fraternity whose role is to purvey the wisdom of scientists to the unwashed masses with little or no innate skepticism. Therefore, we, being engineers, should look into critically different plausibilities even if they may fall short of proof before such highly contagious strains break out on our doorstep in the foreseeable future.

What can engineers do to avert chimeric contagious variants emerging loud?

Looking at the traits mentioned above of Delta variant, the accepted premise for knocking down such high virulent nature would be to (1) transform more transmissible to less, (2) control more virulent to less, and (3) evade more infectiousness caused by asymptomatic and pre-symptomatic by practicing non-pharmaceutical interventions. Table 2 depicts the most likely interventions that could minimize the superspreading events of Delta variant casualties.

Table 2 manifests that engineers have a great role to play in respect of the first premise. It has been a known fact that engineers are at the forefront of inventing technological marvels to combat global public health epidemics. A defining mark of a responsible engineer is to go to great pains to distinguish what they could do to make a change. With the advent of SARS-CoV-2, engineers have been working round the clock in experimenting with copious technological advances to bring in sound engineering technologies to curb this pandemic. To this end, technologies such as bipolar ionization, UV disinfection, ozonation, and applications of HEPA filters gain popularity worldwide. Such technologies would enable to make most of the Delta variant viral loads unviable in no time. The efficiencies of devices incorporating such technologies seem to be remarkably high (greater than 90%), but their use in enclosures or indoor settings is still lacking. The general public has fettered access to such technologically advanced devices in the global market. Engineers, therefore, need to play their role by educating the general public, groups of different fraternities, and even school-going children. Also, there is a greater need for being proactive with positive gestures to implement such devices to make Delta variant viral payloads unviable. Figure 1 depicts a schema of what an engineer could contribute to stopping transmitting Delta variant (B.1.617.2) in comparison to the original virus (B.1).

As depicted in Figure 1, for the Delta variant, vaccination of both shots would still leave a 35% risk of contraction, and it would lessen to 10% with the strict enforcement of non-pharmaceutical interventions. However, although they bring in significant relief, one can not be complacent with these two actions; hence, the third action (engineering control) becomes indispensable. In other words, with the implementation of engineering controls, we could reduce the risk factor to 5%, which is still high enough to disqualify for a Delta-free setting or society. Reducing 5% by engineering controls would undeniably help stem the exponential transmissibility rates of the Delta variant in a given setting. Hence, we should strive hard to instill pro-mindsets among the general public for engineering controls, lessening the casualties of the Delta variant. Comparing the same scenarios for B.1 strain would yield very positive results, but this strain no longer lingers in our environment. Nevertheless, with widespread episodes of Delta variant in our society, one can not rule out a completely COVID-19 free environment in the foreseeable future.

Letting the engineer’s efforts be not frivolous

In the wake of casualties contracted with the Delta variant becoming high in Sri Lanka, engineers should not turn a blind eye to the control of this epidemic. We should be proactive in preventing the spread of the disease by applying engineering control, particularly in indoor settings where population density is high (Office spaces, restaurants, supermarkets, hospitals, etc.). Although future chimeric variants evade the human immune system, engineering controls, if appropriately applied, would not evade their destruction ability; hence, numerous applications could be made plausible. This message has not yet gone viral, but I believe that all engineers take it forward largely to make a change in Sri Lanka, resulting in very low daily casualties. No sooner the general public realizes the importance of such control measures, the engineer’s efforts will not be frivolous. Your continuous contribution and efforts toward saving lives today against virulent virus episodes would be your priority at this difficult hour. By and large, if you do so, you will show the world that you are a responsible engineer worthy of being praised, honored, and respected.


Eng. (Professor) Mahesh Jayaweera

B.Sc. (Civil Eng), Ph.D. (Env Eng)
Professor, Department of Civil Engineering,
University of Moratuwa
Chartered Engineer, Member of IESL, IWA, SLAAS-Section C, and SLAAS-Chair of Committee for the popularization of Science

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