Data Suggests Johnson & Johnson Vaccine Still Effective Against Delta Variant

Johnson and Johnson storefront.

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Key Takeaways

  • New data suggests that the Johnson & Johnson COVID-19 vaccine provides significant protection against hospitalization and death from the Delta variant.
  • Booster shots are likely needed for Johnson & Johnson vaccine recipients, but more data is needed before health officials make a formal recommendation.
  • Although vaccines provide adequate protection against COVID-19, it’s still important to wear masks, maintain physical distancing, and practice proper hand hygiene.

With the rise of the highly transmissible Delta variant, many are concerned that the current COVID-19 vaccines may not hold up. But, if you've got the Johnson & Johnson shot—new research suggests not to worry. You're likely protected from severe disease.

According to new data from a large clinical trial, the Johnson & Johnson COVID-19 vaccine is up to 71% percent effective against hospitalization and 96% percent effective against death from the Delta variant.

The clinical trial is the first real-world test of the vaccine’s efficacy against the highly transmissible variant. For the study, researchers evaluated almost 500,000 healthcare workers in South Africa.

The preliminary results were reported by South Africa’s Ministry of Health at a news conference earlier this month and have not been published in a scientific journal yet. However, it shows more promise than the data the company referenced back in July, which analyzed vaccine efficacy against the Delta variant among eight participants.

Is the Single-Shot Johnson & Johnson Vaccine Effective?

Compared to the two-dose mRNA vaccines like Pfizer-BioNTech and Moderna, the Johnson & Johnson only requires one vaccine dose, which may concern people about its effectiveness against COVID-19.

“The different technologies behind the mRNA versus adenoviral vector vaccines means that there are likely different kinetics of the immune response,” Margaret Liu, MD, board chair of the International Society for Vaccines, tells Verywell. “For example, the expression of spike protein by the mRNA versus from an adenoviral vector may be different, which could affect the kinetics and persistence of the antibody responses.”

Even though the three vaccines with emergency use authorization (EUA) were developed with different technologies, they all provide significant protection against COVID-19.

“Based on the currently available data, people vaccinated with either an mRNA vaccine or the single-dose vaccine should feel very protected from the severe harms of COVID-19 including hospitalization and death,” Arjun Venkatesh, MD, MPH, emergency medicine physician at Yale Medicine and section chief of administration, tells Verywell. 

Since July, the continued spread of the Delta variant has caused a significant uptick in cases nationwide.

“While no vaccine is perfect, both types of vaccine appear to be highly effective against the Delta variant in real-world studies, and when combined with simple behavior changes such as mask-wearing indoors, community transmission rates of SARS-COV-2 are substantially lower,” Venkatesh says.

Will Johnson & Johnson Recipients Need A Booster?

According to the joint statement from the Health and Human Services (HHS), Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC), booster shots are likely needed for those who were vaccinated with the Johnson & Johnson vaccine. However, they are waiting on more data before making an official recommendation.

"It is possible that people will boost their immune responses after a second shot of Johnson & Johnson or after a boost with a different type of vaccine," Liu says. 

Earlier this month, the San Francisco Department of Public Health allowed Johnson & Johnson vaccine recipients to receive a supplemental mRNA vaccine dose should they wish to do so. Health officials made it clear that this is not a recommendation nor a new state requirement, but rather, an accommodation for patients who have consulted with their physician about a supplemental dose.

“There is no published data to suggest that a ‘hybrid’ vaccination schedule would afford better protection yet,” Venkatesh says. “There are ongoing trials that we should expect results from this fall regarding whether receiving one vaccine before another type of vaccine is better.”

A study preprint, which has not been peer-reviewed and should not be used to guide clinical practice, found that a first dose of the AstraZeneca vaccine followed by a second dose of Pfizer-BioNTech vaccine induces higher antibodies than a two-dose AstraZeneca vaccination series.

Ultimately, more research is needed to ascertain if mixing doses of viral vector vaccines—such as Johnson & Johnson—with mRNA vaccines is effective and beneficial.

What This Means For You

If you were vaccinated with the Johnson & Johnson COVID-19 vaccine, you already have significant protection against COVID-19. Health officials say booster doses are likely needed after a certain period, but they need to evaluate more data before making an official recommendation.

Protecting Yourself From the Delta Variant

All the authorized COVID-19 vaccines provide a high degree of protection against severe illness and hospitalization. However, it’s important to continue practicing various safety measures to minimize the spread of the virus and protect those who are extremely vulnerable to disease.

“I don’t like the term 'breakthrough,' since post-vaccination COVID-19 infections have always been expected and the vaccines were not developed to prevent any infection,” Venkatesh says. “They were designed to prevent real harm including hospitalization and death.”

Many were concerned about the CDC's recent report that 74% of infections in the Massachusetts COVID-19 outbreak were among vaccinated individuals. However, as vaccination rates increase, it's expected that a larger proportion of infected people will then be composed of fully vaccinated individuals. It doesn't dismiss the fact that vaccines are still effective.

“While the vaccines are so much better than we had hoped, people should still take long-haul COVID seriously, which can occur even after asymptomatic infections,” Liu says. “The key for everyone, regardless of what vaccine they were immunized with, is to limit unnecessary and risky interactions as much as possible, re-institute masking and social distancing and hand-washing, even when around people you think are immunized, and especially when you don't know.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Johnson & Johnson. Positive New Data for Johnson & Johnson Single-Shot COVID-19 Vaccine on Activity Against Delta Variant and Long-lasting Durability of Response.

  2. The White House. Remarks by President Biden Laying Out the Next Steps in Our Effort to Get More Americans Vaccinated and Combat the Spread of the Delta Variant.

  3. U.S. Department of Health & Human Services. Joint Statement from HHS Public Health and Medical Experts on COVID-19 Booster Shots.

  4. San Francisco Department of Public Health. Health Advisory: COVID-19 Vaccination Updates.

  5. Liu X, Shaw RH, Stuart ASV, et al. Safety and Immunogenicity Report from the Com-COV Study – a Single-Blind Randomised Non-Inferiority Trial Comparing Heterologous And Homologous Prime-Boost Schedules with An Adenoviral Vectored and mRNA COVID-19 Vaccine. Preprints with The Lancet.

  6. Brown CM, Vostok J, Johnson H, et al. Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021. MMWR Morb Mortal Wkly Rep. 2021;70:1059-1062. doi:

By Carla Delgado
Carla M. Delgado is a health and culture writer based in the Philippines.