Covid-19: Delta variant has greater ability to evade immune response, finds study

In a study published in Nature journal, a team of researchers have found that the Delta variant was eight times more likely to escape immunity gained through AstraZeneca or Pfizer vaccines compared to the original coronavirus.

In a possible explanation of the rapid spread of the Delta variant of the SARS-CoV2 virus, a new study has found this particular variant to have a much higher ability to infect, and to evade the immune response built through previous infections or vaccines.

In a study published in Nature journal, a team of researchers from India and other countries have found that the Delta variant (or B.1.617.2 lineage) was eight times more likely to escape immunity gained through AstraZeneca or Pfizer vaccines compared to the original virus. Also, the Delta variant was six times more likely to re-infect people who have recovered Covid-19.

The study also found “higher replication efficiency” in the Delta variant, giving it a better capability to infect and “potentially explaining the B.1.617.2 dominance”.

The study said that “increased replication fitness” and “reduced sensitivity” to neutralising bodies, built either through natural infection or vaccines, had contributed to the rapid spread of the Delta variant in more than 90 countries.

The researchers 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.

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