Johnson & Johnson Vaccine Protects Against Delta Variant, Company Reports The vaccine also produced long-lasting immune responses, researchers said. Booster shots seem unnecessary, at least for now. Natalia Dubom of Honduras got the Johnson & Johnson vaccine at Miami International Airport in May.Credit...Marta Lavandier/Associated Press July 1, 2021 The Johnson & Johnson coronavirus vaccine is effective against the highly contagious Delta variant, even eight months after inoculation, the company reported on Thursday — a finding that should reassure the 11 million Americans who have gotten the shot. The vaccine showed a small drop in potency against the variant, compared with its effectiveness against the original virus, the company said. But the vaccine was more effective against the Delta variant than the Beta variant, first identified in South Africa — the pattern also seen with mRNA vaccines.