Pfizer and BioNTech will test a vaccine against the Delta variant
Pfizer and BioNTech announced on Thursday that they are developing a version of the coronavirus vaccine that targets Delta, a highly contagious variant that has spread to 98 countries. The companies expect to launch clinical trials of the vaccine in August.
The Delta variant, first identified in India, is believed to be about 60 percent more contagious than Alpha, the version of the virus that tore through Britain and much of Europe earlier this year, and perhaps twice as contagious as the original coronavirus. The Delta variant is now driving outbreaks among unvaccinated populations in countries like Malaysia, Portugal, Indonesia and Australia.
Delta is also now the dominant variant in the United States, the Centers for Disease Control and Prevention reported this week. Until recently, infections in the United States had plateaued at their lowest levels since early in the pandemic. Hospitalizations and deaths related to the virus have continued to decline, but new cases may be rising, although it’s not yet clear to what extent the variant is responsible. A slowing vaccination drive and swift reopenings also are playing roles.
In their news release, Pfizer and BioNTech also reported promising results from studies of people who received a third dose of the original vaccine, but the companies did not provide the data. A booster given six months after the second dose of the vaccine increases the potency of antibodies against the original virus and the Beta variant by five to tenfold, the companies claimed.
The vaccine makers expect to submit that data to the Food and Drug Administration in the coming weeks, a step toward gaining authorization for booster shots. Antibody levels in the blood may decline six months after immunization, the companies said, and booster doses may be needed to fend off variants.
But antibodies are only part of the body’s immune response, and independent studies have suggested that immunity induced by full vaccination is likely to remain robust for years, even against variants. A study published in Nature on Thursday found that two doses of the vaccine are highly effective against the Alpha, Beta and Delta variants.
Delta is in the spotlight now, but it is a harbinger of variants to come, underscoring the need to vaccinate the world as quickly as possible. Already the Gamma variant, first identified in Brazil, has found a foothold in Washington State, and a more recent variant, Lambda, is on the march in South America.