Early data suggest a greater increase in CD8+ T-cell response when the Janssen COVID-19 vaccine (Ad26.COV2.S), a viral vector vaccine, is administered as a booster 6 months after a 2-dose primary series with the Pfizer-BioNTech mRNA COVID-19 vaccine (BNT162b2).

The independent study conducted by Dan Barouch, MD, PhD, et al of Beth Israel Deaconess Medical Center included a subset of participants from the COV2008 study (ClinicalTrials.gov Identifier: NCT04999111), which is evaluating booster vaccination with the Janssen COVID-19 vaccine in individuals who previously received primary vaccination with the Janssen or Pfizer-BioNTech vaccine.

“In this preliminary study, when a booster dose of Ad26.COV2.S was given to individuals 6 months after a primary regimen with the BNT162b2 vaccine, there was a comparable increase of antibody responses at week 4 following the boost and a greater increase of CD8+ T-cell responses with Ad26.COV2.S compared with BNT162b2,” said Dr Barouch.

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According to the study authors, the T-cell response data provide early evidence that a mix-and-match booster approach may provide different immune responses than homologous boosting.

“These results provide valuable scientific insights for our vaccine when used as a mix-and-match booster and can help inform boosting strategies with the goal to curb the pandemic,” said Mathai Mammen, MD, PhD, Global Head, Janssen Research & Development, Johnson & Johnson.

In October 2021, the FDA authorized the use of a heterologous booster dose for all currently authorized and approved COVID-19 vaccines following the completion of primary vaccination. After a review of available data, the Agency found that the benefits of a single heterologous booster dose outweighed the known or potential risks.


Johnson & Johnson COVID-19 booster, administered 6 months after two-dose regimen of BNT162b2, shows substantial increase in antibody and T-cell responses. News release. Accessed December 5, 2021. https://www.prnewswire.com/news-releases/johnson–johnson-covid-19-booster-administered-six-months-after-two-dose-regimen-of-bnt162b2-shows-substantial-increase-in-antibody-and-t-cell-responses-301437591.html.

This article originally appeared on MPR