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Most Vaccine Combos Yield Higher Omicron Shield Than Just J&J (1)

Jan. 19, 2022, 8:30 PMUpdated: Jan. 19, 2022, 10:29 PM

Nearly all combinations of Covid-19 shots appear to ramp up antibodies to fight off the omicron variant, although researchers found that two doses of Johnson & Johnson’s vaccine offer the least antibody protection.

The two other vaccines available in the U.S., from Pfizer/BioNTech and Moderna, differ from J&J by using genetic material called messenger RNA, or mRNA, to help the body form antibodies against Covid. An mRNA booster after a J&J vaccine or another mRNA vaccine is effective against omicron, a National Institutes of Health study found.

“A third dose after an initial priming series with mRNA definitely helps in neutralizing against variants of concern, including the omicron variant,” Emily Erbelding, director of the division of microbiology and infectious diseases at the National Institute of Allergy and Infectious Diseases, part of the NIH, said in an interview Wednesday.

The study found that a second shot of J&J’s vaccine elicited the lowest amount of antibody protection against the highly contagious variant compared to three mRNA shots or an mRNA shot after an initial dose of J&J. There are about 12 million Americans who received a J&J shot but haven’t gotten a booster yet.

Although it’s unclear how many of those people are eligible for a booster, the findings could provide some insight as they navigate vaccination decisions while the pandemic continues into its second year.

A J&J booster after a J&J primary vaccine “had a smaller boost” in antibodies, but Erbelding cautioned that those levels offer just one indicator of how much protection against Covid the vaccines offer. Research is ongoing, and forthcoming data on T-cells could give a more robust picture of J&J’s protection against Covid.

The current study, which appears on the pre-print server MedRxiv, comes as the omicron strain now accounts for 98% of cases of Covid-19 in the U.S. Public health leaders have stressed the importance of boosters, but most of the data showing that the additional doses increase antibody levels stems from the Pfizer or Moderna vaccine.

“These data support that most homologous and heterologous boost combinations will increase humoral immunity to Omicron and can be considered as a strategy to mitigate risk from this variant,” the study authors said. The NIH funded the study, which included researchers from across the country.

About 16.5 million people got a J&J shot in the U.S., far less than the 118 million who are fully vaccinated with Pfizer, or the 74 million who opted for Moderna, according to data from the Centers for Disease Control and Prevention. Fewer than 4.2 million people who took J&J’s vaccine have gotten their boosters, and just a quarter of them opted for a second round of J&J. About 42% got a Moderna booster and about 33% received a Pfizer booster.

J&J Plus mRNA

The study authors looked at six combinations, four of which examined the effects of giving the same type of booster as the primary vaccine series. The two remaining study arms looked at Pfizer boosted with J&J, as well as J&J boosted with Pfizer.

The paper didn’t include a J&J primary vaccine with a Moderna booster, though Erbelding said she expects the Moderna booster to perform similarly to Pfizer’s. Data on that combination is forthcoming, she said.

The original study design used a 100-microgram dose of Moderna as a booster, since it began before the company announced it would use a 50-microgram dose for its booster. Erbelding and her team have since added a study arm that looks at the 50-microgram Moderna booster.

The researchers, in the interest of getting the findings out as quickly as possible, chose the “most relevant group” that got an mRNA booster “given the limited bandwidth for the lab that does the virus neutralization assays, and the intense pressure from other studies to test for omicron neutralization, and the fact that our earliest cohorts were boosted with Moderna 100mcg dose,” Erbelding said in an email.

Antibodies vs. T-Cells

Antibody levels—the focus of the research—are just one type of protection, and J&J’s own data shows a booster shot works well against the latest variant of concern.

Erbelding pointed to a separate study from J&J that showed its vaccine builds up durable protection over time, despite being slower than the mRNA vaccines at developing antibodies.

Testing antibody levels in a harmless version of the virus takes less time than evaluating immunity at the cellular level, which requires greater technical investment and research volunteers to come in for study visits. She said those studies are happening now and that an evaluation of the effect of vaccines on T-cell response will probably come out in several months.

The CDC has encouraged Pfizer and Moderna’s booster over J&J’s as part of an overarching recommendation to opt for mRNA vaccines when possible. Regulators have shortened the recommended interval between primary and booster doses to five months from six months for those who received the Pfizer or Moderna vaccine.

A study published in the fall indicated that a J&J primary vaccine followed by a Moderna booster may offer the best antibody response. A study published last month found two shots of J&J in South Africa cut hospitalizations caused by the omicron variant up to 85%. A third study indicated J&J’s vaccine may be slower at revving up antibodies but provides durable protection.

The authors of the mix-and-match study noted real-world data is needed on the effectiveness of vaccines against the omicron variant, as well as a better understanding of how well other parts of the immune system, such as T-cells, work in fighting off the disease.

J&J didn’t respond to a request for comment.

(Updated with additional reporting in the 11th, 12th, and 13th paragraphs. )

To contact the reporter on this story: Jeannie Baumann in Washington at

To contact the editors responsible for this story: Alexis Kramer at; Fawn Johnson at

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