Delta variant 8 times less sensitive to COVID vaccine antibodies, more infectious than Wuhan strain: Study

The Delta variant of the coronavirus is eight times less sensitive to antibodies generated by the COVID-19 vaccines than the original Wuhan strain, a study conducted on 100 healthcare workers in Delhi has found.

The study also discovered that the Delta variant also is also more infectious than the Wuhan strain.

The study from India entitled Sars-Cov-2 B.1.617.2 Delta variant Emergence and Vaccine Breakthrough: Collaborative Study, a collaborative effort with scientists from Cambridge Institute of Therapeutic Immunology & Infectious Disease is available online as a non-peer reviewed preprint version in Research Square.

The study found the Delta variant is less sensitive to neutralising antibodies from recovered individuals, with “higher replication efficiency" as compared to the Alpha variant.

“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, but also generates greater transmission between fully vaccinated healthcare workers, as compared to other variants B.1.1.7 (Alpha variant) or B.1.617.1 (Kappa variant)," the study noted.

Speaking of Delta variant's increased transmissibility, the study found the variant has enhanced spike proteins for attachment to the lung epithelial cells, which provided it a much higher capacity to infect many more people than the original Wuhan strain.

“From this study it appears that we have to go miles before we sleep in case of COVID-19 pandemics," said Dr Chand Wattal, chairperson, Institute of Clinical Microbiology & Immunology, Sir Ganga Ram Hospital.

"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 behaviour."

“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 for 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,” Dr Wattal added.