Possible reasons of rapid spread and dominance of Delta variant found in new study
A team of researchers revealed that Delta variant was eight times more likely to escape immunity acquired through vaccines compared to original virus.
A new study has revealed that the Delta variant of the SARS-CoV2 virus has a much higher ability to infect and evade the immune response built through previous infections or vaccines. The study published in the Nature journal can be seen as a potential answer as to why the dominance of the Delta variant is witnessed around the world.
The study conducted by a team of researchers from India and other countries revealed that the Delta variant was eight times more likely to escape immunity acquired through vaccines compared to the original virus. The study also found that the Delta variant was six times more likely to re-infect people who have recovered from COVID-19. The researchers found 'higher replication efficiency' in the Delta variant meaning it has a better capability to infect.
The study revealed that what contributed to the rapid spread of the Delta variant in more than 90 countries is the 'increased replication fitness' and 'reduced sensitivity' to neutralising bodies. The SARS-CoV-2 B.1.617 lineage includes three main subtypes - B1.617.1, B.1.617.2, and B.1.617.3.
The study
The researchers studied individuals who were vaccinated with the AstraZeneca or Pfizer COVID-19 vaccines.
It found that the B.1.617.2 lineage was eight times more likely to escape immunity gained through the above vaccines compared to the original virus.
They also studied breakthrough infections amongst almost 9,000 fully vaccinated healthcare workers in three Delhi hospitals.
A total of 218 workers at these hospitals had symptomatic infections even after taking both doses of the Covishield vaccine.
The prevalence of the Delta variant in this cohort was found to be 5.45 times more than other variants.