Big gap between Pfizer, Moderna vaccines seen for preventing COVID hospitalizations

At a mobile clinic in Los Angeles, a dose of Pfizer BioNTech COVID-19 is prepared. (Irfan Khan / Los Angeles Times)
The Centers for Disease Control and Prevention released Friday a report that found that America's best shot at fighting severe disease is not as effective as many experts thought.

The Pfizer-BioNTech vaccine is shown to reduce the chance of COVID-19 hospitalizations by 91% when data was collected in 18 states from March through August. However, vaccine efficacy drops below 77% after 120 days.

Moderna's vaccine was still 93% effective in reducing short-term COVID-19 hospitalizations and it remained 92% after 120 days.

Overall, 54% have received the Pfizer shot.

These surprising results came after a panel of experts from the Food and Drug Administration recommended that booster doses not be offered to Americans over 16 years old. The agency was rebuffed by 16 of 18 experts who stated that they had not received enough data to recommend a third shot.

Representatives from Pfizer presented lengthy briefings to panel members. They cited clinical trials involving 306 healthy participants in order to argue that boosters "restore" the 95% vaccination effectiveness rate seen earlier during the pandemic.

Officials from the company also cited evidence from Israel that boosters were being used after a spike in hospitalizations among fully vaccinated people. According to Israeli scientists, hospitalizations fell dramatically after the third dose.

Panel members pointed out that Pfizer had not provided enough evidence to show that a third shot is safe for young people or those at lower risk of developing COVID-19-related complications.

Dr. Ofer Levi, a member of the panel who directs the Precision Vaccines Program at Boston Children's Hospital, stated that "we need age-specific information" about the safety and protective effects of a booster.

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FDA approval for booster shots for all people 16 years and older would be considered "close to a mandate," according to Dr. Eric Rubin (a Harvard T.H. panel member) and infectious-disease expert. Chan School of Public Health. Rubin was concerned that this move would redefine what it means to be fully vaccinated against COVID-19.

He said, "None of our are there yet."

Others, however, seem to be. Dr. Anthony Fauci is President Biden's top vaccine advisor. He stated before Friday's vote, that it would be a mistake to not endorse booster shots.

Biden said in August that his administration would make booster shots available to all who have been vaccinated for at most eight months.

Biden warned at the time that his plan was dependent on FDA approval. However, Biden's announcement raised concerns about political meddling in a matter which required an unhindered assessment by scientists.

After the vote, Dr. Archana Chatterjee of Chicago Medical School stated that "this should demonstrate to the public, that the members of the committee are independent from the FDA." "In fact we bring our voices to this table when asked to serve on the committee.

The panel unanimously agreed that Comirnaty, the current brand name for the vaccine, should be given to select groups. These include people 65 years and older, those at high risk of severe illness, and healthcare workers whose jobs put them at high infection risk.

Panel members were told by Dr. Peter Marks that the FDA could approve booster shots using an emergency authorization. This regulatory step is not as comprehensive as the approval Pfizer sought.

Friday's statement by the company was not in response to panel's vote.

For months, researchers in the United States warned that immunity provided by COVID-19 vaccines may be declining. The CDC reported in July that close to three quarters of the 469 victims in a Massachusetts epidemic had been fully vaccinated. The agency also launched several studies to detect changes in vaccine effectiveness among healthcare workers who were vaccinated earlier.

However, almost all of these infections were mild. Fauci and Dr. Rochelle Walsky, directors of the Centers for Disease Control and Prevention, have repeatedly praised vaccines for keeping the most fully vaccinated out of hospitals.

This expectation is challenged by the new report on declining vaccine efficacy.

At a clinic for mass vaccination in Ontario, Calif., Pfizer-BioNTech COVID-19 is displayed on a tray (Irfan Khan/ Los Angeles Times).

Researchers across the country discovered striking differences in two mRNA vaccinations that were long believed to be interchangeable.

The company announced that the Moderna vaccine was granted emergency use authorization in December. It reported that thirty patients in the clinical trial had developed severe COVID-19 symptoms, nine of whom required hospitalization. The vaccine effectiveness against severe diseases was 100% for all 30 patients who were in the placebo group.

Pfizer's first clinical trial found that ten people developed severe COVID-19. Nine were in the placebo group and seven were admitted to hospital. This resulted in an 88.9% vaccine effectiveness against severe diseases.

After the Moderna and Pfizer vaccines had been made available to the public, their records in preventing COVID-19 hospitalizations within the first four months were at a neck-and-neck 93% and 91%, respectively. However, the protection levels began to diverge after that.

The Moderna vaccine was 92% effective in preventing COVID-19 hospitalizations when they were examined for 120 days. The equivalent number for the Pfizer vaccine was 77%.

These results were published in the CDC’s Morbidity and Mortality Weekly Report.

Moderna and Pfizer vaccines both use mRNA technology. This is a temporary instruction to the body's muscles cells that helps it recognize spike protein, which is a crucial part of the coronavirus structure. However, they are not interchangeable according to Dr. Timothy Brewer at UCLA, who is a professor of medicine, epidemiology, and medicine.

Brewer stated that each vaccine is made and administered in a different way. This could impact the strength or duration of protection.

Modernas shot has 100 micrograms of vaccine. This is more than three times as much as the Pfizer shot's 30 micrograms. Modernas two doses of vaccine are administered three weeks apart by Pfizers, while Modernas' two-shot regimen has a four-week break.

Brewer also highlighted evidence that Moderna vaccine seems to produce higher levels of a key antigen than the Pfizer vaccine.

According to him, other studies have shown that neutralizing antibodies will eventually degrade over time. Therefore, starting at a higher level means you have more to go before your efficacy decreases.

Robert Murphy, director of Northwestern University's Institute for Global Health said that the Pfizer vaccine's lower protection against severe diseases may make it more compelling to give boosters for everyone who received the vaccine and not just those who were identified by the FDA advisory board.

According to the data I've seen, people who have received the Pfizer vaccine will benefit from a booster dose. "I don't see why we should wait until the sickest people are admitted to hospital.

Dr. Arnold Monto is the FDA advisory panel chair and he applauds the agency's willingness not to make a loud call for boosters until the case is stronger. He suggested that boosters for all could still be granted the nod as evidence builds.

Monto, an epidemiologist from the University of Michigan, said that "that's the beauty of emergency use authorization." It can be modified based on changes in data.

This story first appeared in Los Angeles Times.