mRNA Vaccine Candidate BNT162b2 Shows Promise; Recommended for Large-Scale Trials

mRNA Vaccine Candidate BNT162b2 Shows Promise; Recommended for Large-Scale Trials

A recent study by researchers in the US and Germany of two mRNA-based COVID-19 vaccine candidates found that while they both lead to neutralizing antibodies, the candidate BNT162b2 was associated with less reactogenicity in older folks, “supporting its selection for further phase 2/3 clinical trials.” Given the 806,000 people who have died as of August 24, an effective vaccine is urgently needed. So, Pfizer and BioNTech launched unprecedented and coordinated studies to contrast four RNA COVID-19 vaccine candidates, “in umbrella-type clinical studies.” The goal was to select a single candidate and dose level for a future, “global safety and efficacy trial.”

Battle of the Vaccines: BNT162b1 versus BNT162b2

As reported August 23 by News Medical, a leading open-access medical and life science news hub, the study looked at two lipid nanoparticle-formulated mRNA candidates. One, BNT162b1, encodes the virus’ “receptor-binding domain,” while the other, BNT162b2, encodes SARS-CoV-2’s “full-length spike protein to increase its potential for eliciting virus-neutralizing antibodies.” Prior data on BNT162b1 hinted that it may be a promising vaccine, but more data on elderly folks was needed. US and German researchers described the work: “Here we report the full set of safety and immunogenicity data from the Phase 1 portion of an ongoing randomized, placebo-controlled, observer-blinded dose-escalation U.S. trial that was used to select the final vaccine candidate, BNT162b2, as well as comparison of the safety and immunogenicity of both vaccine candidates’” 

BNT162b2 Shows Lower Negative Side Effects

In the study, safety and immunogenicity of BNT162b1 and BNT162b2 at various doses. Folks aged 18-55 and 65-85 were randomized in the trial. They got either a placebo or two of the mentioned vaccines. In sum, both vaccines elicited a similar immune response. BNT162b2, “was associated with lower systemic reactogenicity (i.e., inflammatory response to vaccination such as injection-site pain and redness), particularly in elderly individuals included in this study.” Based on these results, the researchers advise large-scale safety and efficacy tests for BNT162b2. “The primary consideration driving this decision was the milder systemic reactogenicity profile of BNT162b2, particularly in older adults, in the context of comparable antibody responses elicited by both candidate vaccines,” say the researchers in the medRxiv paper.