Delta Plus Variant
Instead of painting gloomy picture about the newly emerged ‘Delta Plus’ variant of SARS CoV-2 virus, I would like to present the logic interpretation of speculations surrounding the new variant.
World Health Organisation, as of June 14, had classified the Delta Plus variant (technically named B.1.617.2.1 or AY.1.) as Variant of Concern.
A variant of concern (VoC) carries the highest threat perception of a coronavirus variant, which is characterised by increased infectivity, transmissibility or resistance to vaccines and treatment.
Delta Plus variant possesses not only all of the characteristics of the original Delta variant but also a mutation known as K417N, which was discovered in the Beta variant in South Africa, with fears that this mutation might be able to evade both immunity from vaccination as well as immunity conferred by earlier infections.
K417N is a mutation in the spike protein of the Sars-CoV-2 which helps the virus to latch on to human bodies and enter human cells.
Since the Delta variant is causing major threat in many countries and was a predominant variant of devastating second wave in India, Delta Plus, an offshoot of Delta variant is being theoretically considered as bigger threat.
‘Delta Plus’ variant was first seen in Europe in March 2021, but was brought to public notice on June 13.
Public Health England (PHE) does not use the ‘Plus’ label and instead refers it as Delta-AY.1., since it is considered part of the Delta variant, rather than a new variant.
The first case of Delta Plus variant in India was reported in a 65-year-old woman from Bhopal, who had recovered from COVID-19 under home isolation and was also administered two doses of the vaccine.
Two cases reported in Ratnagiri, Maharashtra, India were also asymptotic.
Mysuru, India has reported the first case of Delta Plus variant in Karnataka, and the infected person is asymptomatic and none of his contacts have contracted the virus.
Tamilnadu has reported the first case in Chennai, India (tested positive on May 5th), who had mild illness and she recovered under home quarantine.
Her contacts at workplace and family did not have any symptoms and were found to be negative for Covid-19.
As a precautionary measure Central govt. in India has asked chief secretaries of the states which are reporting the variant to take up immediate containment measures in the districts and clusters, including preventing crowds and intermingling of people, widespread testing, prompt tracing as well as vaccine coverage on a priority basis.
Speculated functional changes in ‘Delta Plus’ variant
1. Increased transmissibility
Though the new variant was identified from March 2021, so far no evidence for the Delta Plus variant in community circulation anywhere in the world.
Most of the Delta Plus variant infected persons recovered in home quarantine and none of the family member got infected with the disease.
According to the experts, “We do not have any indicators as of now to show that Delta plus should be causing any public health worry or panic”.
Moreover, this mutation has not changed the route of transmission and hence the social vaccine (behavioural changes) like, masking, social distancing, hand-washing, avoiding three ‘C’s still remains the same.
2. More severe illness due to stronger binding capacity to receptors of lung cells
From the past experience of second wave in India, we have come across considerable mortality not due to the pathogenicity of the virus per se, but due to scarcity of appropriate medical facility, mismanagement of available resources, delayed appropriate medical care, scarcity of relevant drugs etc.
Now, the government authorities and private hospitals have improved upon their short comings and are confident of facing any eventuality with better case management, which should bring down the case fatality rate in the event of wide-spread infection with Delta Plus variant.
The natural infection immunity (acquired during the second wave) in majority of the population, should have some protection against the severity of the disease since the Delta Plus variant is an offshoot of Delta variant.
Even in all those reported cases in India, the illness was mild and required only home quarantine.
So far, no deaths were reported among Delta Plus infected cases anywhere in the world including India.
Moreover, resistance to the therapy may not indicate the higher virulence of the virus or severity of a disease.
Only when there is a study on this aspect will give an overview of the possibility.
3. Potential reduction in monoclonal antibody treatment response
As stated earlier, while there may be some setback in the use of commercial antibody cocktail due to the new variant, resistance to the therapy is not an indication of higher virulence or severity of a disease.
Further, it is only the ‘monoclonal antibody’ treatment response is reduced and not for other line of treatments.
Moreover the monoclonal antibody treatment was adopted only in few covid-19 cases, due its prohibitive cost (Rs 59,750 per dose), scarce availability and ‘limited stage appropriate’ management benefits.
4. Reduced immune response to presently available vaccines or prior infected persons
Delta plus might have a slight advantage at infecting and spreading between people who were previously infected earlier during the pandemic or who have weak or incomplete vaccine immunity.
Every possibility of adverse impact of the Delta Plus variant on available vaccines is only an assumption by the experts, and the ICMR and the NIV are now planning to conduct a study about ‘vaccine-induced antibody’ escape feature of the Delta Plus variant.
Even if it is the case, only those countries which have already vaccinated majority of the population with the presently available vaccines have to rethink on incorporating a booster dose or administering a newer vaccine capable of tackling the new variant.
As far as Indian scenario, it seems there is blessing in disguise as we have vaccinated only around 7% of the population and majority of the population are already infected with the ‘Delta’ variant (during second wave), from which the new Delta Plus variant emerged.
Which means Indian population would have acquired some partial ‘natural-infection induced’ antibody protection against the delta plus variant and have the possibility of getting vaccinated with appropriate vaccine/vaccination schedule in future.
Moreover It is important to note that antibodies are not the sole immune defence against Covid-19 and antibodies alone do not indicate the immunity of a person.
This is so because of T-cells undergo certain changes when we receive the vaccine or get infected.
Till date, we have limited understanding of the involvement of T-cells in immunity against SARS-CoV-2.
Whether the Delta Plus variant can cause devastating third wave in India?
Third wave due to Delta Plus variant may be a remote possibility, because when we observe the timeline (from first identification of delta plus variant and its subsequent Covid-19 incidence in India), there is no marked changes in the incidence of Covid-19.
According to NITI Aayog of India, the `Delta Plus` variant has been present in India since March 2021, but no significant increase in prevalence.
It is assumed by scientist community that majority of the population is infected with Delta virus during second wave, but we have done only less than 1% genome sequencing of reported cases in India, which brings doubt about the presence of Delta Plus variant during second wave itself.
One reason for hope is that, unlike in January and February 2021, the Government Authorities are preparing the healthcare system for another wave.
Understanding this continued evolution of SARS CoV-2 is of great importance in mapping the evolutionary landscape of emerging variants.
Regions where the Delta Plus variant has been found, may need enhancement of the public health response by focusing on surveillance, enhanced testing, quick contact-tracing and priority vaccination.
So, it’s fair to keep an eye on the new variant but not panic.
Original article written by Dr.Mathivanan, Rtd. DDHS from India