Vaccine Info

Flucelvax Influenza Vaccine

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Last reviewed
February 12, 2024

Flucelvax® Influenza Vaccines

Flucelvax® Quadrivalent (QIVc) is a cell culture-based flu vaccine to protect against four flu virus strains recommended by the World Health Organization (WHO) for the current influenza season and 2024. Initially Approved by the U.S. Food and Drug Administration (FDA) in 2016, Flucelvax is now indicated (STN: BL 125408) for everyone six months and older eligible to receive an influenza vaccine for active immunization for the prevention of influenza disease caused by influenza virus subtypes A and types B contained in the vaccine. Flucelvax Quadrivalent was developed using the MF59® adjuvant.

CSL Seqirus Flucelvax is the first FDA-approved flu vaccine to use cells instead of chicken eggs and represented the first significant advance in flu vaccine manufacturing technology since flu vaccine production began in the 1930s. This modern manufacturing process allows the flu shot to be antibiotic-free, helps protect against the identified four flu strains for 2020-2021, and is well-tolerated. Moreover, cell-based flu vaccine production does not use flu viruses grown in eggs and is not dependent on the eggs' supply. Also, cell-based flu vaccines that use cell-based candidate vaccine viruses (CVVs) can offer better protection than traditional, egg-based flu vaccines. The U.S. Centers for Disease Control and Prevention (CDC) confirmed in June 2023 that viruses used to make cell-based vaccines may be more similar to circulating "wild" flu viruses than those used to make egg-based vaccines.

The U.S. CDC says Cell-based influenza vaccine technology may offer advantages over the standard influenza manufacturing process, including being more scalable and offering faster production during an influenza pandemic. On June 21, 2023, the Advisory Committee on Immunization Practices (ACIP) presented considerations and proposed recommendations for the 2023-2024 flu season in the U.S. On February 22, 2023, the CDC's ACIP agenda highlighted preliminary data on the effectiveness of cell-based influenza vaccines (i.e., Flucelvax) during the 2022-23 flu season. Additionally, data presented by the Marshfield Clinic Research Institute on February 22, 2023, demonstrated that cell-based influenza vaccines, such as FluecelVax®, provided 71% effectiveness in children between 6 months and 18 years and 54% effectiveness among certain adults.

In the United Kingdom and European Union, QIVc is marketed as FLUCELVAX® TETRA.

As of February 8, 2024, Seqirus intends to distribute FlucelVax without the B/Yamagata influenza virus strain by the 2024/25 flu season.

CSL Seqirus reported on February 12, 2024, half year revenue of $1,804 million, up 2% over last year's same period. In the U.S., CSL Seqirus operates a state-of-the-art cell-based manufacturing facility in Holly Springs, NC, purpose-built in partnership with the Biomedical Advanced Research and Development Authority (BARDA) to increase cell-based vaccine manufacturing capacity and combat pandemic influenza threats. On August 15, 2023, the Company announced that good progress was made on constructing the new cell-culture influenza vaccine facility in Melbourne, which is expected to be operational in 2026. Seqirus is part of CSL Limited (ASX: CSL), headquartered in Melbourne, Australia. The CSL Group employs over 20,000 people in more than 60 countries.

Flucelvax Quadrivalent Vaccine Indication

On March 7, 2023, the FDA announced the Influenza Virus Vaccine Strain composition for the 2023 - 2024 influenza season. A six months+ age indication for FLUCELVAX® is now approved in the U.S., Argentina, Canada, Taiwan, Australia & New Zealand to prevent disease caused by influenza A subtype and type B viruses in the Vaccine. In addition, the U.S. FDA recommends cell vaccines to contain the following for the 2021-2022 flu season: A/Wisconsin/588/2019 (H1N1)pdm09-like virus; A/Cambodia/e0826360/2020 (H3N2)-like a virus; B/Washington/02/2019 (B/Victoria lineage)-like virus; B/Phuket/3073/2013-like (B/Yamagata)-like virus.

Flucelvax Trivalent Vaccine Indication

The B/Yamagata influenza virus strain is being removed from Seqirus influenza vaccines distributed in the U.S., preferably by the 2024 - 2025 flu season. 

Flucelvax Vaccine Pediatric 

A study funded by Seqirus CLS and published on October 15, 2023, concluded using a QIVc is effective in pediatric patients, with evidence of incremental benefits over using a QIVe in preventing hospitalizations and influenza-related medical encounters in nearly all published studies. The use of QIVc in pediatric populations is cost-effective as part of a broader scheme across age groups, and the lack of potential for mismatch due to egg adaption, together with manufacturing benefits, means that cell-based influenza vaccines can play an essential role in population-level protection against influenza.

Flucelvax Vaccine Pregnancy

On October 25, 2023, Gregg C. Sylvester, MD, MPH, Seqirus, presented at the ACIP Meeting - Pregnancy Outcomes with ccIIV4 (Flucelvax); Post Marketing Study. The independent expert committee found no evidence of a safety concern. These data support the use of ccIIV4 for immunization against influenza in pregnant women and the fetus/infant population. Additionally, Nicky Klein, MD, PhD Director, Kaiser Permanente Vaccine Study Center, presented the safety of quadrivalent recombinant influenza vaccine in pregnant women and their infants. In summary, within a large population of influenza-vaccinated pregnant women, comparing RIV4 with SD-IIV4, there were no differences in pregnancy, birth, and neonatal/infant outcomes. No safety concerns were identified after RIV4 use in pregnancy.

CSL Seqirus presented original safety data at the Infectious Diseases Society for Obstetrics and Gynecology annual meeting from a new prospective observational cohort study evaluating pregnancy outcomes and fetal events of interest following vaccination with the Company's cell-based Flucelvax QIVc. The study found no unexpected adverse pregnancy outcomes in pregnant women in the U.S. who were vaccinated with QIVc.

On July 30, 2021, Seqirus announced a 'prospective observational cohort study that evaluated pregnancy outcomes and events of interest in the fetus or infant following vaccination with QIVc during any trimester. "Pregnant people (women) and people (women) who have recently given birth can be particularly vulnerable to infectious diseases like influenza," commented Christopher Robinson, M.D., MSCR, Charleston Maternal-Fetal Medicine and study author, in a press release. "These data provide further reassurance on the safe use of seasonal influenza vaccines in pregnant people (women)."

Flucelvax Quadrivalent Price

CSL Seqirus provides a coding and billing guide for healthcare providers. The CDC vaccine price list indicates this flu shot will range from $26.95 to $28.44. The U.S. CDC confirms that the Vaccines For Children program provides vaccines and medicines to children at no cost. And InstantRx™ is a digital gateway empowering people to find lower-priced medicines and vaccines easily.

Flucelvax Vs. Egg-Based Vaccines

On December 19, 2023, Original Research should real-world evidence (RWE) evaluating clinical outcomes among seniors ≥65 years have shown a superior clinical benefit of aII adjuvanted trivalent vaccines over standard egg-derived quadrivalent inactivated influenza vaccines. In a meta-analysis of RWE from cohort design studies, the pooled estimate for the relative vaccine effectiveness of V3 compared with IIV4e for the prevention of influenza-related medical encounters was 13.7% (95% confidence interval: 3.1%–24.2%).

Flucelvax Quadrivalent and COVID-19 Vaccines

The U.S. Centers for Disease Control and Prevention (CDC) issued interim clinical considerations in April 2021, stating that 'COVID-19 vaccines and other vaccines, including influenza vaccines, can be administered without regard to timing. The annual influenza vaccination is recommended for all persons aged six months and older who do not have contraindications. 'Providers should be aware of the potential for increased reactogenicity with coadministration and consult the CDC for updated guidance as more information becomes available. If coadministered, COVID-19 vaccines and vaccines that might be more likely to cause a local reaction (e.g., aIIV4 or HD-IIV4) should be administered in different limbs, if possible.'

Flucelvax Quadrivalent Dosage

Flucelvax Quadrivalent is a vaccine for intramuscular injection only and is also preservative and latex-free. Flucelvax is available as a 0.5ml intramuscular vaccine per dose for the 2021-2022 U.S. influenza season.

Flucelvax Quadrivalent Side Effects

CSL Seqirus published a FluCelVax vaccine side effect disclosure in 2016, followed by Australia, and the EMA updated Flucelvax Tetra in 2020. The most common (≥10%) local and systemic reactions in adults 18-64 years of age were injection site pain (45.4%), headache (18.7%), fatigue (17.8%), and myalgia (15.4%), injection site erythema (13.4%), and induration (11.6%), according to the U.S. FDA.

VAERS is a U.S. passive reporting system, meaning it relies on individuals to send in reports of their experiences with a vaccine. Anyone can submit information to VAERS, including parents and patients. Furthermore, healthcare providers are required by law to report to VAERS. People are also encouraged to report adverse side effects of prescription drugs to the FDA. Visit or call 1–800–FDA–1088.

Flucelvax Coding Information

Access information about coding and billing for Seqirus flu vaccines.

Influenza Pandemic Plans

The following documents guide the United States and the World Health Organization's preparedness and response to influenza pandemics. Note: Annual flu shots are not designed to offer protection from avian pandemic viruses. Flu season 2023-2024 trends are posted at this link.

Flucelvax Quadrivalent News

February 8, 2024 - "Influenza continues to cause significant public health burden, and the agility to rapidly adapt vaccines to match the circulating strains remains paramount. We are proud to say that we have responded swiftly to meet the FDA's directive and are committed to working with health authorities to support this transition ahead of the 2024/25 flu season," said Gregg Sylvester, Chief Health Officer and Head of Medical Affairs, CSL Seqirus.

October 11, 2023 - CSL Seqirus announced new data from three studies supporting cell-based and adjuvanted seasonal influenza vaccines' clinical, public health, and economic value. The data highlights the effectiveness and value of influenza vaccination in the U.S. across all relevant age groups, risk profiles, and influenza seasons with different levels of influenza burden.

August 15, 2023 - CSL Seqirus reported FLUCELVAX® sales recently increased by 30%.

July 17, 2023 - CSL Seqirus announced it has begun to ship 55 million cell-based, adjuvanted, and egg-based influenza vaccines across the U.S.

September 26, 2022 - Seqirus published data that "show the benefits of adjuvanted and cell-based influenza vaccine technology advances, like aTIV and QIVc, in reducing influenza-related outcomes compared to high-dose or standard vaccines in the real-world setting," said Dr. Gregg Sylvester, Chief Health Officer

July 11, 2022 - CSL Seqirus announced the shipping of their influenza vaccines for the 2022/23 flu season. 

June 6, 2022 - Seqirus announced the completion of an expansion to the Company's manufacturing facility in Holly Springs, N.C., supporting the formulation and fill-finish of its cell-based influenza vaccines in pre-filled syringes for global communities. The U.S. FDA-approved manufacturing facility and pre-filled syringe line will allow Seqirus to increase its capacity to supply the U.S. market with FLUCELVAX® QUADRIVALENT vaccines.

June 2, 2022 - Seqirus announced its manufacturing facility in Holly Springs, North Carolina. It has successfully achieved all criteria required to establish domestic manufacturing capability for cell-based seasonal and pandemic influenza vaccines as outlined by the Biomedical Advanced Research and Development Authority (BARDA). Additionally, the joint investment enables Seqirus to sustain the production of differentiated seasonal cell-based influenza vaccines.

October 19, 2021 - Seqirus presented new real-world evidence (RWE) at the global International Society for Influenza and Other Respiratory Virus Diseases (ISIRV). Most notably, Seqirus' cell-based quadrivalent seasonal influenza vaccine (QIVc) was more effective than standard, egg-based quadrivalent influenza vaccines (QIVe) in reducing influenza-related medical encounters (IRME) in children (aged ≥4 to ≤17) and adults (aged ≥18) during the U.S. 2019/20 U.S. influenza season.

October 15, 2021 - New Jersey-based Seqirus announced that the U.S. FDA had Approved FLUCELVAX® QUADRIVALENT for an expanded age indication for children as young as six months old.

August 19, 2021 - Seqirus announced plans to accelerate the development of its next generation of messenger RNA (mRNA) vaccine technology, self-amplifying messenger RNA (sa-mRNA), by creating a dedicated s-mRNA program. Seqirus is developing several sa-mRNA-based influenza vaccine candidates, with pre-clinical results demonstrating promise compared to more traditional influenza vaccine technologies. The Company targets clinical trials for seasonal and pandemic influenza vaccine candidates in the second half of 2022.

July 30, 2021 - Flucelvax Quadrivalent Vaccine (QIVc) was safe for pregnant women. "These data provide additional safety information regarding unexpected pregnancy complications and/or fetal outcomes to healthcare providers considering vaccination to protect their pregnant patients from the flu," said Josephine van Boxmeer, lead Clinical Scientist for the study at Seqirus and an author. "We are committed to helping to protect as many people as possible against influenza, including those who are pregnant."

May 3, 2021 - Seqirus-US presented new Phase 3 clinical data demonstrating that the Company's cell-based quadrivalent seasonal influenza vaccine (QIVc) was as safe and immunogenic as a standard quadrivalent seasonal influenza vaccine (QIV) in children six months through <4 years of age during the U.S. 2019/20 influenza season.

March 18, 2021 - Seqirus announced that Health Canada had approved FLUCELVAX® QUADRIVALENT.

March 4, 2021 - Seqirus announced that the U.S. Food and Drug Administration had approved FLUCELVAX® QUADRIVALENT (Influenza Vaccine), the Company's cell-based quadrivalent influenza vaccine (QIVc), for an expanded age indication for people two years of age and older.

December 9, 2020 - Seqirus presented new real-world evidence at the European Scientific Working Group on Influenza 2020 showing the clinical benefits of a cell-based, quadrivalent seasonal influenza vaccine (QIVc) in preventing influenza-related medical encounters compared to an egg-based quadrivalent influenza vaccine (QIVe) during the 2018 - 2019 United States in the influenza season.

October 29, 2020 - Seqirus presented absolute efficacy data on the Company's cell-based quadrivalent influenza vaccine (QIVc) from a randomized controlled trial, which met its primary endpoint in children and adolescents between ≥2 to <18 years of age over three influenza seasons.

July 30, 2020 - Seqirus announced it has begun shipping its portfolio of seasonal influenza vaccines to customers in the U.S. for the 2020/21 influenza season. Seqirus is one of the world's largest influenza vaccine companies, well-positioned to supply up to 60 million doses to the U.S. market, depending on demand.

Flucelvax Quadrivalent Vaccine (QIVc) Clinical Trials

Seqirus continues to Evaluate the Efficacy, Safety, and Immunogenicity of QIVc in clinical trials.

Clinical Trials

No clinical trials found