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New studies question efficacy of latest COVID boosters

David Colburn
Posted 1/18/23

REGIONAL- As the most contagious COVID variant yet, XBB.1.5, continues to increase around the country, findings from two research studies reported last week suggest the bivalent COVID booster …

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New studies question efficacy of latest COVID boosters


REGIONAL- As the most contagious COVID variant yet, XBB.1.5, continues to increase around the country, findings from two research studies reported last week suggest the bivalent COVID booster vaccines released last September are no more effective than the original COVID vaccine at staving off the disease.
The bivalent boosters developed by Pfizer and Moderna were specifically tailored to combat the BA.4 and BA.5 COVID variants, which were the dominant strains circulating in the country in late summer and early fall. They were touted as providing a greater boost to immunity than the original version of the vaccine, based primarily on research conducted in animals to more quickly bring the vaccine to market. However, research confirming the real-world effectiveness of the vaccines in humans has been mixed, beginning with a Centers for Disease Control study reported in November that found the new boosters were only 43 percent effective at preventing mild illness compared to receiving no vaccine. Results for those 65 and over showed the boosters were just 22 percent effective.
Last week, two studies published in the highly regarded New England Journal of Medicine offered evidence that the bivalent boosters only attack the COVID-19 virus about as well as the original COVID vaccines.
A study of blood samples conducted by researchers at Columbia University compared antibody levels between individuals who had received a series of four shots of the original vaccine and those who had three doses of the original followed by a bivalent booster. The analysis did not show any discernably superior neutralizing antibody response for those who received the bivalent booster.
Additional research conducted at Beth Israel Deaconess Medical Center in Boston also found that the bivalent vaccines failed to promote higher antibody levels or better immune responses than the original vaccine.
A prepublication review of the Columbia study on the university’s website said, “Our result was a bit disappointing, because we all wanted to see the bivalent booster generate a superior antibody response against Omicron, but our human data show that there’s not a lot of difference between the two types.”
However, chief researcher Dr. David Ho noted that the bivalent boosters do boost antibody levels and recommended their use.
“That doesn’t mean people shouldn’t get the bivalent booster,” Ho said. “In our study we also found that the bivalent booster greatly increases the number of antibodies that neutralize the omicron variants. We still advocate boosting so that folks are better protected. There’s no question that the current vaccines are preventing severe disease and death. And that’s quite important.”
Also last week, some Food and Drug Administration advisers who recommended the bivalent vaccines be approved by the CDC for use expressed concern that early similar research was not provided to them by Moderna or government scientists, according to a report on CNN.
XBB.1.5 spreading
The CDC Variant Proportions tracker reports that for the week ending Jan. 14, cases caused by the most concerning variant among health officials, XBB.1.5, represented 43 percent of cases nationwide, a significant increase from 26 percent the prior week that make it the single-most dominant variant in the country. The proportion of XBB.1.5 cases in the region that includes Minnesota grew to 14 percent.
XBB.1.5 has a unique mutation that allows it to cling more tightly to cells it is trying to invade, and has shown greater transmissibility than any prior COVID variant. The variant has been dubbed “the Kraken” variant, after the mythological sea monster, and has been reported to be 49 times less likely to be neutralized by existing antibodies than the BA.4 and BA.5 variants.
MPR News reported last week that the Minnesota Department of Health’s genetic sequencing laboratory had only seen ten cases of XBB.1.5 so far.
Minnesota appears to have avoided a post-holiday increase in COVID cases and hospitalizations, according to the latest situation update from MDH. COVID cases were down 27 percent as of Jan. 5 compared to the prior Thursday and hospitalizations were down by 22 percent. The most recently reported three-day case average for Minnesota was 647.
The seven-day case average for St. Louis County also reflects a general decline from 38.3 on Dec. 6 to 19 on Jan. 11.