Delta variant Johnson & Johnson good for 8 months Johnson & Johnson said late on Thursday that its Covid-19 vaccine showed strong promise against the Delta variant and other emerging strains and also provided durable protection against the infection more broadly. The US-based company said in a statement that recipients of its single-shot Covid-19 vaccine produced strong neutralising antibodies over the course of at least eight months against all variants including Delta, which was first seen in India and has been spreading around the world. The healthcare company added that its vaccine was 85 per cent effective and could also help prevent hospitalisation and death.