Doctors back booster shots for recent Covid-19 variants, saying vaccines are especially needed now that cooler weather is here

iStock/Getty Images Plus photo illustration via Kaiser Health News

By Al Cross

Kentucky Health News

Kentucky experts largely dismissed concerns about speedy approval of the new coronavirus vaccines on "Kentucky Tonight," a Kentucky Educational Television program, Monday night.

Ilhem Messaoudi, chair of microbiology at the University of Kentucky, said she has been surprised at people who she said are "up in arms" about the lack of human testing on the vaccines, which target the major subvariants of the Omicron variant of the virus.

She said the vaccines were developed with the same technology used for the original vaccine, tweaked "just like we tweak the flu vaccine every year" without testing the tweaked vaccine on humans.

Messaoudi said clinical trials in humans could have taken so long that new variants could become dominant, making them largely useless. "This just required a very quick response," she said.

Dr. Fadi al Akhass of Pikeville agreed. "That virus is very smart," he said. "It can tweak its genetic material very quickly."

That factor was more important than usual because of the calendar. Cool weather is arriving and people are spending more time indoors, where infeciton is likelier.

Food and Drug Administration Commissioner Robert Califf said at a news conference last week that waiting for human trials "would have meant that a fall or winter Covid-19 wave could have arrived without updated vaccines," Priyanka Runwal reports for National Geographic. "Moderna and Pfizer-BioNTech are now conducting human clinical trials to test the safety and efficacy of the modified boosters, but Califf encourages those eligible to get their shots soon."

Still, the limited testing in mice means “We don’t know … how well this is going to work in the real world,” John Swartzberg, an infectious-disease expert at the University of California, told Runwal, who adds, "To what extent these modified shots will reduce reinfections and breakthrough ones remains unknown.

After an FDA committee overwhelmingly approved the vaccines 13-1, the Centers for Disease Control and Prevention recommended that anyone 12 and older who has received at least two doses of the original Covid-19 vaccines get a new one as a booster against the newer variants.

Some on the committee "said they set aside their desire for more information and better data and voted yes out of fear of a potential winter Covid surge, Celine Grounder and Elisabeth Rosenthal report for Kaiser Health News. "They expressed hope that the new vaccines — or at least the vaccination campaign that would accompany their rollout — would put a dent in the number of future cases, hospitalizations, and deaths."

Pfizer presented studies showing that its updated booster provides 1.56 times more neutralizing antibody titers against the Omicron BA.1 virus than a booster using the original vaccine. Moderna’s studies "demonstrated very similar results," Grounder and Rosenthal report. "However, others predict that a 1.5 times higher antibody titer would yield only slight improvement in vaccine effectiveness against symptomatic illness and severe disease, with a bump of about 5% and 1% respectively."

Grounder and Rosenthal note a difference in tweaking flu and Covid-19 vaccines: "With flu vaccines, scientists have decades of experience and a better understanding of how increases in neutralizing antibody titers correlate with improvements in vaccine effectiveness. That’s not the case with Covid vaccines. And if mouse data were a good predictor of clinical effectiveness, we’d have an HIV vaccine by now."

Still, the experts on the KET program said Kentuckians should get the new vaccines. As they spoke, the state's rate of new coronavirus infections was the highest in the nation, according to The New York Times. 

"We're still having nearly 400 patients a day die in the United States," said Dr. Mark Dougherty of Lexington. "That equates to 120 to 140,000 deaths a year, which is much more than the normal influenza year."

Messaoudi recommended getting a flu shot at the same time, since there are no issues with that. "Our immune system can handle more than one antigen at the same time," and does do "on a daily basis," she said.

Dougherty said many people have caught the coronavirus and passed it on to others without knowing it because they had no symptoms. He said as many as 40% of people infected may not feel well for three months, suffering loss of taste and smell, abnormal taste, or fatigue. "It is having a huge impact on a large number of people."