The Johnson & Johnson coronavirus vaccine provides effective protection against the delta variant, according to a small study, offering hope to many developing economies facing a summer surge of the highly contagious strand.

Blood samples obtained from eight inoculated people who participated in a laboratory study showed that Johnson & Johnson’s single-dose shot generated a strong immune response against the delta variant, the New Brunswick, N.J.-based company said. (The results have not been peer reviewed.) Earlier clinical trials had shown the vaccine offered 66% protection against symptomatic infection.

“We believe that our vaccine offers durable protection against COVID-19 and elicits neutralizing activity against the Delta variant,” Paul Stoffels, chief scientific officer at Johnson & Johnson, said in a news release. “This adds to the robust body of clinical data supporting our single-shot vaccine’s ability to protect against multiple variants of concern.”

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The data so far indicates that the three U.S.-approved vaccines offer effective protection against all known variants of the virus. Analysis by British health authorities, drawing on data from a large pool of people, indicates that the Pfizer-BioNTech messenger RNA vaccine provides 96% protection against hospitalization from the delta variant, which was first detected in India.

Moderna also announced Tuesday that its mRNA vaccine only saw a “modest reduction” in neutralizing antibodies against the delta variant when compared with the original strain. Data from a major trial, which was reviewed by the Food and Drug Administration, has indicated the Moderna vaccine offers 94.1% protection against infection from the strand discovered in Wuhan, China.

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There have been rising concerns about how much protection vaccines provide against the highly virulent delta strain, which the World Health Organization said has been detected in almost 100 countries. Health authorities in the Seychelles on Thursday said six fully vaccinated people in one of the world’s most inoculated nations, which has been combating a delta variant surge, had died of the covid-19. Those people had received either an Indian-made version of the Oxford-AstraZeneca vaccine or Sinopharm shots.

(Public Health England said its analysis shows the Oxford-AstraZeneca vaccine also offers effective protection against the delta variant.)

About 12 million doses of the Johnson & Johnson shot, which is based on similar technology as the Oxford-AstraZeneca vaccine, have been administered in the United States. Because only one dose is required for protection – though there has been talk of booster shots – the relatively cheap Johnson & Johnson vaccine had been seen as a potential lifeline for developing countries, which have borne the brunt of the delta variant.

Johnson & Johnson announced in May that it would be providing 200 million doses to Covax, the global initiative to distribute vaccines equitably. In recent weeks, the Biden administration has dispatched 5.5 million doses of the company’s vaccine to Brazil, where the virus has wreaked havoc, and Colombia.

There have been reports of a very small number of dangerous blood clots occurring in people who received the Johnson & Johnson vaccine, which led the United States to briefly pause its rollout in April. Following a safety review, the CDC and the FDA lifted the suspension.