COVID-19: gap observed between vaccines to prevent hospitalizations

Amid continuing concerns that the protection offered by COVID-19 vaccines could weaken, a report released Friday by the Centers for Disease Control and Prevention finds that the brass knuckles are significantly less effective in preventing severe cases of long-term disease that many experts had realized.

Data collected from 18 states between March and August suggests that the Pfizer-BioNTech vaccine reduces the risk of being hospitalized with COVID-19 by 91% in the first four months after receiving the second dose. Beyond 120 days, however, this vaccine efficacy drops to 77%.

Meanwhile, Moderna’s vaccine was 93% effective in reducing the short-term risk of hospitalization for COVID-19 and remained 92% effective after 120 days.

Overall, 54% of fully vaccinated Americans have been immunized with the Pfizer vaccine.

The startling results came as a Food and Drug Administration advisory group recommended not offering booster doses of the Pfizer vaccine to all Americans aged 16 and over. In a stark rebuke, 16 of 18 experts told the agency it had not gathered enough data to make a third shot the norm.

In lengthy panel briefings, representatives from Pfizer pointed to clinical trial results involving 306 mostly healthy participants to claim that a booster “restores” the 95% vaccine efficacy rate seen earlier. in the pandemic.

Company officials also touted evidence from Israel, which rolled out booster shots after seeing an increase in hospitalizations among those fully vaccinated. These hospitalizations dropped dramatically after the administration of the third doses, Israeli scientists said.

But panel members made it clear that despite Pfizer’s aggressive stance, it had not gathered enough evidence that a third shot was safe for young people and for those less at risk of becoming seriously ill with COVID-19. .

“We need age-specific data” on the safety and protective benefits of another booster, said Dr. Ofer Levy, a panel member who heads the Precision Vaccines program at Boston Children’s Hospital.

FDA clearance for booster injections for all people 16 years of age and older would be considered something “close to a warrant,” said Dr. Eric Rubin, panel member and infectious disease expert at the Harvard TH Chan School of Public Health. Rubin feared that such a move would redefine what it takes to be considered fully vaccinated against COVID-19.

“None of us are here yet,” he said.

But others apparently are. Dr Anthony Fauci, President Biden’s senior vaccine adviser, spoke strongly in favor of the booster injections, saying ahead of Friday’s vote that not approving the injections “would be a mistake.”

And in mid-August, Biden himself said his administration would begin offering booster shots the week of September 20 to people who have been vaccinated for at least eight months.

Biden warned at the time that his plan depended on FDA approval. But his announcement fueled concerns of political interference in a case that required unhindered evaluation by scientists.

“This should demonstrate to the public that the members of this committee are independent from the FDA,” said Dr. Archana Chatterjee, dean of Chicago Medical School, after the vote. “In fact, we make our voices heard when asked to sit on this committee. ”

The panel unanimously agreed that a third injection of the vaccine now sold under the brand name Comirnaty should be offered to selected groups: people 65 years of age and older, people at risk of developing serious illness and those , including healthcare workers, whose professions put them at high risk of infection.

Dr Peter Marks, who heads the FDA’s drug and vaccine assessment, told panel members the agency could bless booster injections with emergency use clearance – a regulatory step which does not meet the full approval requested by Pfizer.

The company did not release any statement on Friday in response to the panel’s vote.

Researchers in the United States have been warning for months that the immunity offered by COVID-19 vaccines could decline. The CDC reported that as of the end of July, nearly three-quarters of the 469 people swept up in an outbreak in Massachusetts were fully vaccinated. And the agency has launched several studies to detect changes in vaccine effectiveness in healthcare workers and others who were vaccinated early.

But virtually all of these infections appeared to be mild. And health officials keen to get vaccine skeptics to get vaccinated – including Fauci and Dr Rochelle Walensky, director of the Centers for Disease Control and Prevention – have repeatedly praised the vaccines for having kept most people fully immunized out of hospitals.

The new report on declining vaccine effectiveness challenges this expectation.

Researchers across the country have discovered striking differences between two mRNA vaccines long considered to be interchangeable.

When the Moderna vaccine received emergency use clearance in December, the company reported that 30 people in its clinical trial developed severe cases of COVID-19, nine of which required hospitalization. All 30 patients were in the placebo group, which resulted in a vaccine efficacy against severe disease of 100%.

Ten people in Pfizer’s initial clinical trial developed severe cases of COVID-19. Nine of them belonged to the placebo group, including seven hospitalized, which gave a vaccine efficacy against serious disease of 88.9%.

Once the Moderna and Pfizer vaccines were rolled out to the public, their hospitalization prevention records for COVID-19 in the first four months were neck and neck – 93% and 91% effectiveness, respectively. But the degree of protection subsequently diverged.

When focused specifically on the 120-day period beyond the second dose, the study authors found that the Moderna vaccine remained 92% effective in preventing hospitalizations from COVID-19. But the equivalent figure for the Pfizer vaccine was 77%.

The results were published in the CDC’s weekly Morbidity and Mortality report.

The Pfizer and Moderna vaccines are both based on mRNA technology, which provides temporary instructions to muscle cells in the body that help it learn to recognize the spike protein, a key building block in the coronavirus. But “they’re actually not necessarily interchangeable,” said Dr. Timothy Brewer, professor of medicine and epidemiology at UCLA.

Each vaccine is formulated and administered differently, Brewer said, and those differences could affect the strength and duration of protection of the two vaccines.

Moderna’s vaccine contains 100 micrograms of vaccine, more than three times the 30 micrograms of Pfizer vaccine. And the two doses of Pfizer are given three weeks apart, while Moderna’s two-shot regimen is given with an interval of four weeks.

Brewer also pointed out that the Moderna vaccine appeared to cause higher levels of a key antibody than the Pfizer vaccine.

“We know from other studies that the levels of neutralizing antibodies will decrease over time, so starting at a higher level will mean you have a longer way to go before decreasing to a point where effectiveness drops.” , did he declare.

Dr Robert Murphy, who heads the Institute for Global Health at Northwestern University, said the reduced protection of the Pfizer vaccine against serious illness could strengthen the case for boosters for all who have received the vaccine, and not only for specific groups identified by the FDA Advisory Group.

“From the data that I saw, people who received the Pfizer vaccine would benefit from a booster dose at that time,” he said. “I don’t see why we have to wait for the younger ones to get sick and be hospitalized. “

But Dr. Arnold Monto, who chairs the FDA advisory board, applauded the agency’s willingness to withhold a rock-solid call for recalls until a stronger case can be presented. And he suggested that as more and more evidence accumulates, Boosters for All may still get the green light.

“That’s the beauty of emergency use authorization,” said Monto, an epidemiologist at the University of Michigan. “It can be modified according to the evolution of the data. “