Atlanta—Once bivalent COVID-19 vaccines undergo the Emergency Use Authorization (EUA) process through the FDA and the CDC, they should be available soon afterward, according to public health officials and the vaccines' manufacturers.

That is one of the reasons why the CDC published some guidance on the use of the new vaccines from Moderna and Pfizer-BioNTech. The bivalent COVID-19 vaccine—which adds an Omicron BA.4/5 spike protein component to the current vaccine composition—will be administered as a single booster dose to patients who previously completed a primary series of COVID-19 vaccines, according to the CDC planning guide.

"It is anticipated that bivalent COVID-19 vaccine booster doses may initially be authorized for people ages 12 years and older (Pfizer-BioNTech) and for people ages 18 years and older (Moderna), followed by younger pediatric age groups," according to the information. "It is also anticipated that the bivalent COVID-19 vaccines will only be authorized as a single dose in people who have completed a primary vaccination series but would not vary by number or type of prior booster doses received."

As of mid-August 2022, the federal government had procured 175 million doses of the bivalent COVID-19 vaccine for distribution and administration in fall and early winter, when both the original vaccines and the bivalents would be used based on past of vaccination status, the report noted.

Pharmacists may be interested to know that public health officials expect that many COVID-19 vaccination providers will offer bivalent booster doses, but not all providers are expected to continue carrying primary series COVID-19 vaccines. Only providers planning to continue offering primary series COVID-19 vaccines will need to store both the original (i.e., prototype vaccine) and the new vaccine. The new vaccines will have the same storage and handling parameters as the original vaccine products. The Pfizer-BioNTech bivalent COVID-19 vaccine is expected to be packaged in six-dose vials in cartons of 10 vials each (60 doses total), with a minimum order quantity of 300 doses. The Moderna bivalent vaccine will be packaged in five-dose vials in cartons of 10 vials each (50 doses total), with a minimum order quantity of 100 doses.

Once punctured, each vial is required to be used within 12 hours, which is similar to existing Moderna and Pfizer-BioNTech (gray cap) products, whose vials must be discarded 12 hours or less after the initial puncture. Vaccination providers also will receive ancillary supplies, including a variety of 1-inch and 1.5-inch needles and syringes.

The CDC advised that doses of each vaccine will be made available under thresholds rather than allocations. "This means that at the start of each new order period, doses available for ordering will be replenished up to the threshold for that order period (i.e., with each subsequent threshold, the full number of doses will be available to order)," the guidance noted.

The CDC also pointed out that current plans call for the availability of preordering to allow vaccine to be shipped immediately following EUA. "Prior to EUA, there will be a pre-ordering period consisting of two waves, with an initial pre-EUA threshold for each vaccine in Wave 1 followed by a threshold increase in Wave 2," according to the guidance. "A post-EUA threshold for each vaccine will be refreshed following EUA(s) and CDC recommendation(s) to ensure that each authorized product is able to continuously flow to sites and to ensure no interruption in product availability."

The CDC stated that the supply of the new vaccines will be "sufficient but finite."

In terms of eligibility, the guidance stated that the type and number of COVID-19 boosters that potential recipients have previously received are not expected to matter for the purposes of eligibility for bivalent COVID-19 boosters, although public health officials are expected to recommend a waiting period of a few months for individuals who have gotten boosters very recently.

The CDC also recommended that pharmacists and other vaccine providers offer simultaneous administration of all age-appropriate doses of vaccines for children, adolescents, and adults in whom no contraindications exist at the time of the healthcare visit. "As the demand for seasonal flu vaccines will also increase during this time, providers may have some concerns regarding vaccine storage space," according to the document.

Both Pfizer and Moderna announced that they have requested EUA from the FDA for their vaccines. Pfizer has a booster dose of an Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine for individuals aged 12 years and older, whereas Moderna has the BA.4/BA.5 Omicron-targeting bivalent COVID-19 booster vaccine mRNA-1273.222, which is a 50-mcg booster dose for adults aged 18 years and older.

Pfizer's bivalent vaccine contains messenger RNA (mRNA) encoding the original SARS-CoV-2 spike protein, which is present in the original Pfizer-BioNTech COVID-19 vaccine, together with mRNA encoding the spike protein of the Omicron BA.4/BA.5 variant, according to the companies.

Preclinical data showed that a booster dose of Pfizer and BioNTech's Omicron BA.4/BA.5-adapted bivalent vaccine generated a strong neutralizing antibody response against Omicron BA.1, BA.2, and BA.4/BA.5 variants, as well as the original wild-type strain. A clinical study investigating the safety, tolerability, and immunogenicity of the Omicron BA.4/BA.5-adapted bivalent vaccine in individuals aged 12 years and older was expected to start in August.

Moderna's mRNA-1273.222 targets both the original strain of SARS-CoV-2 and the BA.4/BA.5 subvariants of the Omicron strain, according to a press release. Moderna's application to the FDA is based on preclinical data for mRNA-1273.222 as well as clinical-trial data from a phase II/III study of mRNA-1273.214, a bivalent booster vaccine targeting the Omicron BA.1 subvariant.

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