Pfizer says new Covid booster works better than old one in study

In a trial, Pfizer and its partner BioNTech SE compared blood samples from 36 people older than 55 who had received the bivalent booster to a control group of people over 55 who had received a fourth dose of the original shot. One month later, antibody levels against the BA.4 and BA.5 variants were four-fold higher in people who had received the bivalent shot when compared with people who had received another dose of the original vaccine, the companies said in a statement.

The Pfizer-BioNTech finding contrasts sharply with recent results from two independent labs at Columbia University and Harvard University. Both of those teams reported in October that bivalent boosters made by Pfizer and rival Moderna Inc. didn’t appear to provide much incremental benefit when compared with a fourth dose of the original vaccines, according to studies posted on the preprint server bioRxiv.org.

Pfizer’s own study, however, suggests that the bivalent shot “may induce a higher level of protection against the omicron BA.4 and BA.5 sublineages than the original vaccine,” the company said in its statement. The company has shared the findings with the US Food and Drug Administration and said it plans to give them to regulators elsewhere soon. 

Debate Implications

Pfizer didn’t release a direct comparison of how the bivalent booster fared against four doses of the original shot in adults younger than 55. But it did say that the bivalent shot raised antibodies against the BA.4 and BA.5 strains 9.5-fold in the 18- to 55-year-old age group compared to their pre-booster levels. In the over-55s, it raised antibody levels 13.2-fold. By comparison, a fourth shot of the original booster raised antibodies 2.9 times in people over 55. 

It is not clear why various studies have produced what appear to be divergent results. All of the studies are small and have not yet been published in scientific journals. 

The debate over the findings may have important implications. Both the Harvard and Columbia studies hint that the immune system response may become biased toward protecting against the original version of Covid virus. If true, that’s a potential problem that companies developing booster shots against future variants will have to find ways to surmount. 

Rollout of the new bivalent boosters from Moderna and the Pfizer-BioNTech partnership are off to a slow start in the US. The Centers for Disease Control and Prevention estimates that only about 26 million people have received them so far.

This story has been published from a wire agency feed without modifications to the text.