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- SARS-COV-2 B.1.617.2 Delta Variant Emergence and vaccine breakthrough and emergence collaborative study:
- Mutant has enhanced spike proteins for attachment to the lung epithelial cells which has provided it Wuhan higher capacity to infect many more people than the wuhan strain.
India
healthysoch
New Delhi, July 5, 2021 :
Recent research study (attached) on B.1.617.2 Delta Variant on over 100 HCW (health care workers) across three centres in Delhi including Sir Ganga Ram Hospital has revealed that in vitro, the variant is less sensitive to neutralising antibodies in sera from recovered individuals, with higher replication efficiency as compared to the Alpha variant. The study is available on-line as a non-peer reviewed preprint version in research in RESEARCH SQUARE. It is a collaborative study from India with scientists from Cambridge Institute of Therapeutic Immunology & Infectious Disease.
In an analysis of vaccine breakthrough in over 100 healthcare workers across three centers in India, the B.1.617.2 Delta variant not only dominates vaccine-breakthrough infections with higher respiratory viral loads compared to non-delta infections (Ct value of 16.5 versus19), but also generates greater transmission between fully vaccinated HCW as compared to other variants B.1.1.7 or B.1.617.1
In Vitro, the Delta Variant shows 8 fold approximately reduced sensitivity to vaccine-elicited antibodies compared to Wuhan-1.
According to Dr. Chand Wattal, Chairperson, Institute of Clinical Microbiology & Immunology, Sir Ganga Ram Hospital, “From this study it appears that we have to go miles before we sleep in case of Covid-19 pandemics. These mutations are bound to happen if we lower our guard and allow ourselves to fall prey to this virus giving it an opportunity to multiply and achieve better fitness with our Covid inappropriate behavior. This is a straight eye opener to the fully vaccinated people that you cannot lower guard in the name of vaccination. Virus is on prowl still looking of its prey. *This mutant has come back with enhanced spike proteins for attachment to the lung epithelial cells which has provided it much higher capacity to infect many more people than the Wuhan strain.”
These combined epidemiological and in vitro data indicate that the dominance of the Delta variant in India has been most likely driven by a combination of evasion of neutralising antibodies in previously infected individuals and increased virus infectivity resulting in the second wave. Whilst severe disease in fully vaccinated HCW was rare, breakthrough transmission clusters in hospitals associated with the Delta variant are concerning and indicate that infection control measures need to continue in the post-vaccination era.
The B.1.167.2 Delta variant appears more transmissible than B.1.1.7 in the UK based on recent data and the dominance of new infections by this variant. In the absence of published data on transmissibility of the Delta variant we predicts that this variant will have a transmission advantage relative to Wuhan -1 with D614G in individuals with pre-existing immunity from vaccine / natural infection as well as in settings where there is low vaccine coverage and low prior exposure. Lower protection against B.1.351, the variant with least sensitivity to neutralizing antibodies, has been demonstrated for at least three vaccines. However, progression to severe disease and death was low in all studies. Therefore, at population scale, extensive vaccination will likely protect against moderate to severe disease and will reduce hospitalisation due to the Delta variant.Dr.
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