Moderna Now Says Vaccine Protection Goes Down After This Long

The vaccine manufacturer says the data supports the case for a booster shot.

As more time passes since the majority of vaccinated people in the U.S. got their COVID shots, experts have been keeping an eye on how immunity fares in the months thereafter. Moderna recently said data shows that those who were vaccinated this year had more protection against COVID than those who got their shots last year. According to the vaccine manufacturer, the shot's protective power is lower about a year after you've been vaccinated.

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In a Sept. 15 statement, Moderna said that a study showed that people who were vaccinated more recently, a median of eight months since their first shot, had a lower risk of breakthrough infection than those who were vaccinated last year, a median of 13 months since their first shot. The company said it believes this data supports the need for a booster shot.

The study found that of the 11,431 people vaccinated between December and March, 88 had breakthrough cases. Meanwhile, of the 14,746 participants who were vaccinated between July and October of last year, 162 had breakthrough cases. Although people who were vaccinated more recently had a lower chance of a breakthrough infection, the study also demonstrates how rare breakthrough cases are in general.

Officials at Moderna are now pushing for a booster shot. On Sept. 1, the company submitted its application to the U.S. Food and Drug Administration (FDA) for authorization of a third dose.

In the Sept. 15 statement, Moderna CEO Stéphane Bancel, said, "The increased risk of breakthrough infections in COVE study participants who were vaccinated last year compared to more recently illustrates the impact of waning immunity and supports the need for a booster to maintain high levels of protection."

Reuters reported that during a conference call with investors, Moderna president Stephen Hoge said, "This is only one estimate, but we do believe this means as you look toward the fall and winter, at minimum we expect the estimated impact of waning immunity would be 600,000 additional cases of COVID."

Hoge said the data from booster studies indicates that an additional dose would significantly increase neutralizing antibodies, raising levels higher than after the second dose. He said the company believes boosters "will reduce COVID cases" and extend immunity "throughout much of next year as we attempt to end the pandemic." Hoge added that "the first six months [of protection] are great, but you can't count on that being stable out to a year and beyond."

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However, this new data from the vaccine manufacturer tells a somewhat different story than other research. Recent studies have shown that Moderna's vaccine protection is stronger and extends longer than Pfizer's. According to Reuters, experts believe the extended protection is due to Moderna's higher dose of mRNA and the slightly longer interval between the two shots.

A Sept. 10 study from the Centers for Disease Control and Prevention (CDC) found that Moderna was more effective than Pfizer or Johnson & Johnson at preventing COVID-related hospitalizations and urgent care visits. An earlier study published Aug. 19 in JAMA Internal Medicine found that people who received Moderna developed more spike IgG antibodies than those who got Pfizer, resulting in better protection. And recent research from the Mayo Clinic also demonstrated that Moderna is more protective than Pfizer. The Aug. 8 study showed that Moderna recipients had a two-fold risk reduction for breakthrough cases, as compared to those who received Pfizer.

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