Moderna argues the F.D.A. should authorize a half-dose of its vaccine as a booster.

On the grounds that the vaccine’s ability to protect against infection diminishes with time, the company Moderna argued in documents made public on Tuesday that the Food and Drug Administration should approve a half-dose of its coronavirus vaccination for recipients at least six months after the second dose.

Breakthrough infections, “real world evidence of reduced effectiveness,” and falling antibody levels six to eight months after a second dose were all cited as reasons why Moderna’s vaccine was less effective against the Delta variant than other vaccines. A third injection boosted antibody levels—a measure of the immune system’s response—to a higher level than before the second dose, according to the company’s clinical trials.

The FDA made the documents public ahead of a two-day meeting of the agency’s external advisory committee on Thursday and Friday. The F.D.A. released its own briefing document for the committee on Tuesday, summarising the data without taking a position.

The committee is expected to vote on whether to recommend that both Moderna’s and Johnson & Johnson’s vaccines be given an emergency authorization for booster injections. Although the panel’s votes are not binding, regulators tend to follow them in the event of a tie.

There is no evidence to support Moderna’s claim that its vaccine is no longer effective in preventing serious illness or hospitalisation. Moderna’s application is distinct from Pfizer-last BioNTech’s month. The FDA stated in a briefing document: “Some real world effectiveness studies have suggested declining efficacy of Moderna Covid-19 vaccine over time against symptomatic infection or against the Delta variant, while others have not.”

There are “many potentially relevant studies,” according to the agency, but none of the underlying data or conclusions have been independently reviewed. Overall, the data show that Moderna and the other vaccines “still provide protection against severe Covid-19 disease and death in the United States,” according to the report.

The Food and Drug Administration and the Centers for Disease Control and Prevention have agreed to allow some but not all Pfizer-BioNTech vaccine recipients to receive emergency boosters. Elderly, those who reside in long-term care facilities, those who have underlying medical conditions, or those who are at greater risk of exposure to the virus due to their work or institutional settings are all eligible for this programme. There are also educators and correctional officers in this final group of workers.

The F.D.A. proposed that the outside experts consider essentially the same groups of Moderna recipients in a document released Tuesday. There are reports that the federal government may ask the committee to consider expanding the number of middle-aged people eligible for boosters of both vaccines.

Moderna’s two-dose vaccine remains effective against mild, moderate, and severe Covid-19 for an unknown amount of time, according to several independent studies. More than 15,000 Moderna clinical trial participants, some of whom had been vaccinated over a year prior, were studied for cases of Covid-19 last summer. Participants who were fully vaccinated between July and October 2020 were compared to those that were vaccinated between December and March 2021 in terms of Covid-19 cases in July and August.

People who were vaccinated later had a 36% lower risk of Covid disease than those who were not. There was no statistically significant difference between the two groups when it came to severe Covid cases, according to lead researcher Dr. Hana M. El Sahly, a professor of molecular virology at Baylor College of Medicine.

There was no need for a booster, according to her findings. The study was supported by the National Institutes of Health, according to the researchers.

More recently, the Centers for Disease Control and Prevention (CDC) conducted a study of nearly 3,700 patients in 21 different hospitals between March and August of this year. Over the course of six months, Moderna’s vaccine performed better than either Pfizer or Johnson & Johnson’s vaccines.

Researchers found Moderna to be 93% effective in preventing hospitalisation, while Pfizer and Johnson & Johnson were only 88% and 71% effective, respectively. Four months after the second shot, Pfizer’s effectiveness against hospitalisation dropped to 77%, while Moderna’s remained largely stable, they reported.

Covid-19 Booster Shots: What You Need to Know

Is a booster shot right for you?

A small group of people who received their second dose of the Pfizer-BioNTech vaccine at least six months ago were given permission by the FDA to receive booster shots. Adults 65 years of age or older who reside in long-term care facilities, as well as health care workers and others whose jobs put them at risk for severe Covid-19, all fall into this category. Four weeks after the second injection, people with weakened immune systems can receive a third dose of either Pfizer or Moderna.

What about those who received vaccines from Moderna or Johnson & Johnson?

Moderna and Johnson & Johnson vaccine boosters have not yet been approved by regulators, but an FDA panel is scheduled to meet to discuss booster shots for adult recipients of the vaccines.

Booster shots are only given to people who have certain medical conditions.

There are a number of conditions that qualify someone for a booster shot, including hypertension and heart disease; diabetes or obesity; cancer or blood disorders; a weakened immune system; chronic lung or kidney disease; dementia and certain disabilities. Additionally, pregnant women and current and ex-smokers can apply.

Boosters are available for a variety of professions.

Workers whose jobs place them in close proximity to others who may be infectious were given permission by the Food and Drug Administration to receive booster shots. Emergency medical workers, educators, food and agriculture workers, manufacturing workers, corrections workers, U.S. Postal Service, public transportation, and grocery store workers are all included in this group.

Is it possible to use Covid vaccines in combination with other vaccines?

Not a good idea, to be honest. A Pfizer booster shot is currently recommended for Pfizer vaccine recipients, while Moderna or Johnson & Johnsen recipients should wait until those manufacturers have approved a booster dose.

Is it possible to get a flu shot and a Covid vaccine or booster shot at the same time?

Yes. There is no need to schedule a flu shot separately from a booster dose, as the Centers for Disease Control and Prevention (CDC) has stated that the Covid vaccine can be administered without regard to the timing of other vaccines.

The advisory committee’s discussions on booster shots for Moderna recipients are likely to revolve around three central questions given the lack of data showing that Moderna’s protection weakens against severe disease over time.

Even if all three vaccines are effective for different lengths of time, is it necessary for the country to “harmonise” its booster strategy? With many Pfizer-BioNTech vaccine recipients already receiving boosters, some federal officials believe the answer is yes.

It’s also possible that Moderna’s vaccine may be less effective against severe Covid than Pfizer’s vaccine, which has been shown to lose effectiveness over time. Some advocates of additional vaccinations believe that Moderna’s vaccine is less effective against severe disease than Pfizer’s because the initial dosage of Moderna is significantly stronger and the interval between the first and second shots is longer.

Is a booster for mild or moderate disease necessary for recipients of Moderna, even if the data shows that they don’t need it for protection against severe Covid?

There is a fundamental question that needs to be answered, said Dr. El Sahly. When it comes to mild to moderate disease, Moderna and Pfizer seem to have faded, especially with the Delta variant.” Hence, a booster is required if that’s your goal. It’s a different math if we want to prevent only the most serious diseases that end up in the hospital.”