Skip to main content

Johnson & Johnson says COVID-19 vaccine protects against delta variant

Johnson & Johnson vaccine vials and syringe.
(Image credit: Shutterstock)

The Johnson & Johnson COVID-19 vaccine is highly effective against the highly transmissible delta variant, the company announced on Thursday (July 1). 

Though the analysis was conducted on only a small number of participants and hasn't yet been peer-reviewed, it suggests that the Johnson & Johnson vaccine, like the Pfizer and Moderna's vaccines, may provide a buffer for the U.S. against the highly transmissible variant. The findings were submitted as two separate studies to the preprint server bioRxiv.

The delta variant (B.1.617.2) was first discovered in India in October 2020, and the World Health Organization designated it a "variant of concern" in May 2021, Live Science previously reported. The variant has spread to at least 92 countries and prompted new COVID-19 restrictions in some places. In the U.K., the delta variant now accounts for more than 90% of newly diagnosed cases, and in the U.S., it currently makes up more than 20% of new cases, Live Science reported.

Related: Quick guide: COVID-19 vaccines in use and how they work 

Delta is thought to be around 60% more transmissible than the alpha variant, the variant first discovered in the U.K. and the one that is currently dominant in the United States. A recent study conducted by Public Health England found that Pfizer's COVID-19 vaccine was 88% effective against symptomatic disease caused by the delta variant, while AstraZeneca's vaccine was 60% effective against the variant, Live Science reported. 

Because Moderna's COVID-19 vaccine is very similar to Pfizer's vaccine (they're both mRNA vaccines), experts think it will likely confer a similar amount of protection. But less was known about how protective Johnson & Johnson's vaccine would be against the delta variant. Some experts predicted that the Johnson & Johnson vaccine would confer similar protection against delta as the AstraZeneca vaccine because they use the same platform, according to The New York Times. But the two vaccines have some differences, the major one being that Johnson & Johnson’s vaccine is given in a single dose, whereas AstraZeneca’s is given in two doses.

The new data is based on two separate analyses. The first, based on data from eight participants in the company's phase 3 trial, found that the vaccine generated neutralizing antibodies — immune system cells that bind to the virus and inactivate it before it can infect cells — against the delta variant.

The second analysis, conducted by researchers at the Beth Israel Deaconess Medical Center in Boston, analyzed data from 20 participants enrolled in an earlier clinical trial testing the vaccine. They found that the Johnson & Johnson vaccine protects people against SARS-CoV-2 for at least eight months and generates "neutralizing antibodies against a range of SARS-CoV-2 variants of concern," including delta, the company wrote. (Protection may persist beyond eight months, but this is the timeframe that researchers have studied so far).

The level of neutralizing antibodies increased with time: People had a higher average number of neutralizing antibodies eight months after they were vaccinated compared with 29 days after they were vaccinated, according to the statement. The vaccine also generated immune system cells known as T cells that lasted for over eight months. 

"Current data for the eight months studied so far show that the single-shot Johnson & Johnson COVID-19 vaccine generates a strong neutralizing antibody response that does not wane; rather, we observe an improvement over time," Dr. Mathai Mammen, the global head of Johnson and Johnson's Janssen Research & Development, said in the statement. "In addition, we observe a persistent and particularly robust, durable cellular immune response."

Moderna and Pfizer have previously both announced that their vaccine protects for at least six months, according to CNN. A small new study found that the mRNA vaccines might even provide protection for years if the virus doesn't evolve significantly, Live Science previously reported

Originally published on Live Science.

Yasemin Saplakoglu
Yasemin is a staff writer at Live Science, writing about biology and neuroscience, among other science topics. Yasemin has a biomedical engineering bachelors from the University of Connecticut and a science communication graduate certificate from the University of California, Santa Cruz. When she's not writing, she's probably taking photos or sitting upside-down on her couch thinking about thinking and wondering if anyone else is thinking about thinking at the exact same time.