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Many Vaccines Offer Protection as Boosters but Pfizer’s, Moderna’s May Work Best

December 6, 2021

Several different COVID-19 booster shot combinations appear to improve protection against infection but the messenger RNA (mRNA)-based jabs from Pfizer and Moderna might be the most effective.

That’s according to researchers affiliated with the UK’s National Institute for Health Research (NIHR) who have published their findings in The Lancet. Beyond reinforcing the mix-and-match approach that FDA regulators cleared this fall, the research offers insights into which boosters help provide the greatest protection against the coronavirus.

The multicenter phase 2 study inoculated nearly 2,880 participants aged 30 years and older who had previously received a primary vaccination series with either the AstraZeneca or Pfizer/BionTech COVID-19 shots. The AstraZeneca vaccine is not authorized in the U.S., although it has been authorized in the UK and EU.

Trial participants then got a booster dose from among a range of different vaccines, including already authorized vaccines from Moderna and Johnson & Johnson (J&J) and those awaiting regulatory clearance, such as experimental products from Novavax, Valneva and Curevac.

For almost all the shots, neutralizing antibodies and immune responses were significantly boosted by a third dose, including against the Delta variant for Pfizer/BioNTech and Moderna boosters, said the researchers, noting that “this was, to our knowledge, the first randomized trial of third-dose booster vaccines given 10 to 12 weeks after an initial course” of either the AstraZeneca or Pfizer/BioNTech vaccines.

“Data from our study and others suggest that current mRNA doses might be higher than required to provide adequate boost to immunity after a third dose,” the researchers said, highlighting the Pfizer/BioNTech and Moderna shots.

But the NIHR scientists acknowledged that “although neutralizing antibody titers after mRNA vaccination are higher compared with adenovirus-vector vaccines [traditional inactivated jabs such as the AstraZeneca or J&J shot], there are much smaller differences in T-cell responses.”

In related vaccine news, the European Medicines Agency’s safety committee confirmed Friday that the risk of heart inflammation is a very rare side effect of receiving either a Pfizer/BioNTech or Moderna jab, and that this risk is highest in younger males.

Read The Lancet study here: bit.ly/3rzPxzB. ― Jason Scott