COVID-19: Johnson & Johnson vaccine recipients benefit from mRNA boosters

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CDC says effectiveness rises when Pfizer, Moderna are second shots.

COVID-19 booster shots are effective in protecting against hospitalizations for people who received Johnson and Johnson (J&J) vaccines, according to a new study.

The U.S. Centers for Disease Control and Prevention published the results as the federal Food and Drug Administration authorized second booster doses of the Pfizer-BioNTech or Moderna vaccines for certain immunocompromised patients and people age 50 or older.

Adults who received a primary vaccine and booster of the J&J vaccine at least four months ago may now receive a second booster dose using an mRNA vaccine, according to CDC.

“We found that any booster strategy is better than a single J&J dose, which should encourage anyone who has only had a J&J vaccine to get a second COVID-19 vaccine as soon as possible, especially before the expected next surge in COVID,” Brian Dixon, PhD, MPA, senior author of the study, said in a news release. “Individuals with three doses of mRNA had the strongest level of protection against severe consequences from the disease, but being boosted made a significant difference in protection for those who had J&J vaccines.”

The latest study examined 80,287 emergency department/urgent care visits and 25,244 hospitalizations across 10 states from Dec. 16, 2021, to March 7, 2022, when the Omicron variant was predominant variant.


Vaccine effectiveness against COVID-19-associated emergency department and urgent care visits was 24 % after one J&J vaccine. It increased to 54% after two J&J doses, and 79% after one J&J dose plus an mRNA booster from Pfizer-BioNTech or Moderna.

That’s compared to 83 percent after three mRNA doses, the news release said.

Vaccine effectiveness for the same strategies against COVID-19 associated hospitalizations was 31% for the single J&J shot, 67% for two J&J shots, 78% for one J&J shot and an mRNA booster, and 90% for three mRNA doses.

“Even though our study focused on booster effectiveness during the period of Omicron prevalence, data continue to show that we should expect that boosters will be effective against new variants as they emerge,” Dixon said in the news release. “This paper reinforces the importance of getting boosted. It’s important to do it now when rates of disease are low, so you are protected against the resurgence that we expect to see later this year, especially among individuals in high-risk groups.”

Researchers noted the findings had at least five limitations based on factors such as timing and a “small number” of J&J vaccine recipients.

Dixon works with the Regenstrief Institute and Indiana University Richard M. Fairbanks School of Public Health. It is part of the CDC’s VISION Network of universities and health care systems that serves patients across 10 states and that oversaw the study.

The formal title is: “Effectiveness of Homologous and Heterologous COVID-19 Booster Doses Following 1 Ad.26.COV2.S (Janssen [Johnson & Johnson]) Vaccine Dose Against COVID-19–Associated Emergency Department and Urgent Care Encounters and Hospitalizations Among Adults — VISION Network, 10 States, December 2021–March 2022.”