Johnson & Johnson has said that its single-shot Covid-19 vaccine showed promise against the highly contagious Delta variant in a laboratory study, Reuters reports.

An analysis of blood from eight patients showed that immune responses elicited by the vaccine against the Delta variant, first identified in India, were at a higher level than against the Beta variant, which was first identified in South Africa.

"We believe that our vaccine offers durable protection against Covid-19 and elicits neutraliaing activity against the Delta variant," Johnson & Johnson Chief Scientific Officer Paul Stoffels said.

However, disease experts believe the J&J's vaccine may require booster shots of the Pfizer/BioNTech or Moderna vaccines to be more effective against the Delta variant.

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