FDA Considers Second COVID-19 Booster Shot

Carolyn Crist

February 22, 2022

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The FDA has begun reviewing data to potentially authorize a fourth dose of the Pfizer and Moderna COVID-19 vaccines for the fall.

The planning is still in the early stages for a second booster dose, people familiar with the process told The Wall Street Journal. The authorization would depend on ongoing studies, which must show that a fourth dose would increase waning immunity and reduce the risk of severe disease.

As part of the discussion, U.S. health regulators want to find out if a second booster shot should be authorized for all adults or particular age groups. In addition, the FDA is considering whether the vaccine should target the Omicron variant or have a different formula. Health experts are also investigating whether a fourth shot could begin an annual COVID-19 vaccination program, the newspaper reported.

Targeting the fall for the second booster dose could make sense because many people get an annual flu shot then, experts said. At the same time, health regulators may need to consider a fourth shot sooner if another devastating coronavirus variant appears.

But some Americans may not want a fourth dose if they're tired of taking COVID-19 vaccines or remain hesitant about getting the first doses.

About 69% of the eligible U.S. population is fully vaccinated, according to the latest data from the CDC. About 45% of fully vaccinated people have received a booster shot.

Among those 65 and older, 89% have been fully vaccinated, and 66% have been boosted. Older Americans and those who face a higher risk of infection could be open to getting a fourth dose, the newspaper reported.

Researchers have debated whether a fourth dose is necessary, particularly against highly contagious variants such as Omicron or new ones that may emerge. Some reports have suggested that protection from a third dose of the Pfizer or Moderna vaccine remains strong overall, though the risk of hospitalization increases over time.

According to a CDC report released 2 weeks ago, a third dose was 87% effective against emergency room visits and urgent care visits and 91% effective against hospitalizations during the 2 months after vaccination. But by the fourth month after a third dose, vaccine effectiveness dropped to 66% against visits to emergency rooms and urgent care centers and 78% against hospitalizations.

Without a third shot, protection against hospitalization within 2 months of a second shot was 71%, which fell to 54% after 5 months. Protection declined significantly as the Omicron variant became dominant in the U.S., the CDC researchers found, and they recommended that Americans "remain up to date" with vaccinations and boosters to protect against hospitalization.

While considering a fourth dose, U.S. regulators have kept an eye on research in other countries, particularly Israel, which has led the way in giving extra doses. Israel has authorized a fourth dose for certain groups, including people ages 60 and older, immunocompromised people, and health care workers.

In late January, Israel's Health Ministry announced that a fourth shot provided 3 to 5 times as much protection against serious illness and 2 times as much protection against infection, compared with those who were 4 months after their third shot.

Broadly, some vaccine makers have already begun preparing for booster shots to become an annual practice, the newspaper reported. Pfizer is testing a vaccine that targets the Omicron variant and has said that people may need an annual shot, with high-risk people such as the immunocompromised and older adults potentially needing another dose sooner.

Moderna also began testing an Omicron-specific booster shot in January, the newspaper reported, including among people who have already received a third shot of the original vaccine.


The Wall Street Journal: "FDA Eyes Second Covid-19 Booster Shot."

CDC: "COVID-19 Vaccinations in the United States," "Waning 2-Dose and 3-Dose Effectiveness of mRNA Vaccines Against COVID-19-Associated Emergency Department and Urgent Care Encounters and Hospitalizations Among Adults During Periods of Delta and Omicron Variant Predominance — VISION Network, 10 States, August 2021-January 2022."

Israel Ministry of Health: "Fourth Dose Approved for People Above 18 with Underlying Conditions, and Contacts at the Workplace," "Preliminary Data Analysis: Effectiveness of the Fourth Dose for Older Adults 60 Years of Age and Older."


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