Saturday November 27, 2021

Delta calling

July 21, 2021

Ancient Greek alphabets, alpha, beta, gamma, delta…. are once again being used widely worldwide – this time recommended by the World Health Organization (WHO) to refer to different variants of Covid-19 for non-scientific purposes.

This recommendation is based on three reasons. First, Greek alphabets are easy to pronounce and remember. Second, an alphabetic sequence can reveal the order in which the variants were discovered. And third, the alphabets are non-stigmatizing. Scientists and scientific research follow the nomenclature systems established by GSAID, Nextstrain, and Pango – B 1 1 7 for alpha or the British variant, and B 1 6 1 7 2 for the Delta or Indian variant.

Here it is pertinent to mention that until Donald Trump used the term ‘Chinese Virus’ to stigmatize China, it was common to refer to pathogenic viruses by the name of the place where they were first identified. The Ebola virus is named after a river in Congo, the Zika virus after a forest in Uganda and the West Nile virus after a district of that country.

How do the new variants evolve? Here is a non-technical explanation. A virus attacks a host cell, fuses with it, and passes on instruction for replication (to produce more viruses). Commonly, slight copying errors (or genetic changes) known as mutations occur during this replication process. These mutations distinguish the new viruses from their parents. As an epidemic widens, so does the range of mutations.

Not all, but certain mutations may affect the virus’s properties, such as its transmissibility, virulence (disease symptoms), or the response to diagnostics, vaccines and therapeutics. A variant associated with one or more of the above changes at a degree of ‘global public health significance’ is classified by the WHO as a variant of concern. Alpha, beta, gamma, and delta are variants of concern (VOCs).

For the first time in the history of pandemics, scientists are doing real-time monitoring (within their constraints) of the Covid-19 virus for mutations. That has led to the discovery of the Iota, Kappa, and Lambda variants in the US, India, and Peru, respectively, during the last three months. The three are not VOCs yet but have enough potential to be so, hence being closely monitored and called variants of interest (VOIs).

Data from the Centres for Diseases Control and Prevention US, and Public Health England suggest that Epsilon (US), Alpha (UK) and Beta (South Africa), Gama (Brazilian), and Delta variants are 1.25, 1.5, 2.0, and 2.5 times more transmissible respectively than the original virus that was first discovered in Wuhan.

What makes the Delta variant the most dangerous variant of Covid-19 yet discovered is its transmissibility and enhanced ability to evade the human body’s immune system. These two properties are attributed to the mutations in their protein spikes (signature crown shape structure on virus surface).

Let us see how mutation helps the delta variant to evade our immune system. Our immune system defends the attack of a virus through antibodies produced during earlier infection and/or through a vaccine. When attacked by Covid-19, the antibodies (if present in host cells) trap the invader by binding with its spikes. German researchers have discovered that Delta (and Kappa)’s spikes are mutated in a manner that some of the existing’“weaker antibodies’ may not bind to them as tightly or as often, thus enhancing their chances to escape from the immune system. This research does not challenge the effectiveness of Covid-19 vaccines against the Delta variant. Instead, it emphasizes that even vaccinated individuals should observe all established safety protocols to stay safe from the delta variant.

Once inside the body, the Covid-19 virus latches onto its target (ACE2 receptors, abundantly found in human lungs) through its spike proteins. Mutation at certain spikes is assumed to enhance the Delta variant’s capacity to bind with its receptor. Hence, even a low virus load of the variant may cause more damage. Efficiency in finding and binding a target also increases the transmissibility of the delta variant.

In India, some fully vaccinated healthcare workers also got infected by the Delta variant. This may be due to their exposure to high virus load in hospitals. The greater the number of viruses with better binding capacity and enhanced ability to evade our immune system, the higher the odds that they would find and bind to a host cell, causing infection: no escape from following SOPs.

After the virus binds to a receptor, the next step is fusion and replication. Virologists at the University of Texas have discovered that one of the mutations present in Delta makes it easy for the virus to fuse with the host cell and produce more viruses within a short time – thus potentially making it easier for the person carrying that virus to infect someone else.

Ease of fusion with the host cell may cause more severe disease. According to the British Health System, in Scotland the Delta variant has caused about twice as many hospitalizations than the Alpha variant, which already caused more severe illness than the original SARS-CoV-2.

More people worldwide have got infected and died due to Covid-19 in the first six months of 2021 than in 2020. The Delta virus may not be the sole reason for this – but vaccine inequity is one of the major reasons (another reason is not following Covid-19 SOPs) for the increased infection rate and the emergence of new variants. Let me explain why.

According to the Atlantic magazine, of the three billion vaccine doses administered worldwide, about 70 percent have gone to just six countries; Delta has already been detected in at least 85 countries, including Pakistan.

Pakistan has administered 20.5 million vaccine doses so far. Only two percent of our population is fully vaccinated, and 8.13 percent is partially vaccinated. A more than 90 percent unvaccinated population is a feast for the Delta variant. The more the pandemic spreads, the higher the odds for new and potentially dangerous mutations (Kappa variant in India after the Delta).

Since May 29 this year, for the first time, more than 2500 hundred news infections of Covid-19 were recorded in Pakistan on July 15 (2,545 cases). This was a massive 28.5 percent increase over the 1,980 cases reported a day earlier. After remaining below five percent for nearly two months, Pakistan's Covid-19 positivity rate has once again crossed five percent. It is a clear sign that the NCOC’s warnings about the fourth wave in the country need to be taken seriously.

Only by following Covid-19 SOPs and getting vaccinated can we contain the spread of pandemic. Following SOPs are particularly important in the context of Eid and the forthcoming AJK’s elections. Two crucial factors leading to human disaster through the Delta variant in India were a religious festival (Kumbh Mela) and electoral rallies for the state elections. I hope we are ready to learn from the mistakes of our neighbors.

The writer heads the Sustainable Development Policy Institute.

Twitter: @abidsuleri