Moderna Offers Guidance on Extracting Half Booster Vaccine Dose

A new level of complexity has been introduced for pharmacists and other COVID-19 providers. Not only can recipients opt for any vaccine as a booster, but the dosage of the Moderna booster differs from the initial series. Here is some advice from Moderna on how that should and should not be done.

ATLANTA – As pharmacists have more and more vaccinated Americans lining up for COVID-19 boosters, they might find they need a scorecard to keep up with all of the players.

As of late October, those who received either the Pfizer-BioNTech, Moderna or Janssen (Johnson & Johnson) COVID-19 vaccine(s) and meet specific criteria are eligible for a booster shot 6 months later or more for the first two and 2 months for the last.

Rochelle P. Walensky, MD, MPH, the director of the national Centers for Disease Control and Prevention, made it all official on Oct. 21, 2021, when she endorsed the recommendations of the CDC’s CDC Advisory Committee on Immunization Practices’ (ACIP) recommendation for a booster shot of COVID-19 vaccines in certain populations. That occurred after Food and Drug Administration authorization of the products.

Walensky said those who are 65 or older or adults who live in long-term care settings, have underlying medical conditions or who work or live in high-risk settings are eligible for booster shots. Which type of booster they get is up to the recipient; public health officials have given the okay to mix-and-match vaccine boosters.

With all of that, one of the questions that most plagues pharmacists is exactly how to administer the Moderna vaccine booster. Unlike the other two vaccines, the authorized booster dose is half of the amount used for each shot in the initial series.

The FDA shared some information from Moderna, alerting vaccination providers that the volume of a booster dose is 0.25 mL, even though the primary series of this vaccine is two 0.5 mL doses administered intramuscularly 1 month apart.

The guidance points out that a third 0.5 mL primary series dose at least 1 month following the second dose has been authorized for administration for adults who have undergone solid organ transplantation, or who are diagnosed with conditions that are considered to have an equivalent level of immunocompromise.

Paul Burton, MD, PhD, Moderna’s Chief Medical Officer, points out that his company’s COVID-19 Vaccine is supplied in two multiple-dose vial presentations -- a multiple-dose vial containing 5.5 mL and a multiple-dose vial containing 7.5 mL

The letter provided to the FDA states that primary series doses of 0.5 mL and booster doses of 0.25 mL may be extracted from either vial presentation, with the preference that low dead-volume syringes and/or needles are used.

“When extracting only primary series doses, depending on the syringes and needles used, a maximum of 11 doses (range: 10-11 doses) may be extracted from the vial containing 5.5 mL or a maximum of 15 doses (range: 13-15 doses) may be extracted from the vial containing 7.5 mL,” it explains. “When extracting only booster doses or a combination of primary series and booster doses, the maximum number of doses that may be extracted from either vial presentation should not exceed 20 doses.”

Burton emphasizes that the vial stopper should not be punctured more than 20 times. “If the amount of vaccine remaining in the vial cannot provide a full dose of 0.5 mL or 0.25 mL, discard the vial and contents. Do not pool excess vaccine from multiple vials.”

The guidance goes on to say that administration of the incorrect volume for any dose is a vaccine administration error which should be reported to the Vaccine Adverse Event Reporting System (VAERS).

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