B/PHUKET/3073/2013-LIKE STRAIN (B/PHUKET/3073/2013, BVR-1B)

Table of contents

• What is B/PHUKET/3073/2013-like strain?
• How does B/PHUKET/3073/2013-like strain work?
• Which conditions is it used or studied for?
• How is B/PHUKET/3073/2013-like strain given?
• What do the clinical trials show?
• What side effects are known?

What is B/PHUKET/3073/2013-like strain?

B/PHUKET/3073/2013-like strain (B/PHUKET/3073/2013, BVR-1B) is an influenza B virus strain used as one component of a seasonal influenza vaccine. The full registry name in the CTIS product records also lists it together with other strains: B/AUSTRIA/1359417/2021-like strain, A/DARWIN/9/2021 (H3N2)-like strain and A/VICTORIA/4897/2022 (H1N1)pdm09-like strain.^[1]

The strain is part of Fluad Tetra, a suspension for injection in a pre-filled syringe described as an influenza vaccine (surface antigen, inactivated, adjuvanted). Fluad Tetra is already authorised as a medicine in the EU, under authorisation records EU/1/20/1433/001 and EU/1/20/1433/004, held by Seqirus Netherlands B.V.^[1] Another name used for this vaccine in the registry is aQIV.^[1]

A separate homeopathic product named Influenzinum also lists influenza B virus B/PHUKET/3073/2013 hemagglutinin antigen (formaldehyde inactivated) on its label. This homeopathic product has not been evaluated by the US Food and Drug Administration for safety or efficacy.^[6]

How does B/PHUKET/3073/2013-like strain work?

As a component of an inactivated influenza vaccine, the B/PHUKET/3073/2013-like strain provides surface antigen from the influenza B virus. In Fluad Tetra, the vaccine is adjuvanted, which means it contains an added substance intended to strengthen the immune response. The strain is used in trials measuring antibody responses through hemagglutination inhibition (HI) assays and microneutralization tests.^[1][3]

The registry classifies the substance in the therapeutic areas of virus diseases and respiratory tract diseases.^[1] In the product records, the substance is part of a fixed combination in four product records.^[1]

Which conditions is it used or studied for?

• Influenza virus — the largest trial studies prevention of RT-PCR-confirmed influenza A and/or B disease in adults aged 65 and older.^[5]
• Healthy individuals or individuals with stable comorbidities — a Phase 3 immunogenicity and safety study in adults aged 50 years and older.^[1]
• COVID-19 and flu — a completed Phase 2 trial studied co-administration of an adjuvanted influenza vaccine with a COVID-19 mRNA vaccine.^[4]
• SARS-CoV-2 and influenza — a completed Phase 2 trial studied co-administration of BIMERVAX with an adjuvanted seasonal influenza vaccine.^[2]
• Avian influenza and seasonal influenza — a Phase 3 trial studies immune responses to avian influenza vaccines alongside seasonal influenza vaccines.^[3]

How is B/PHUKET/3073/2013-like strain given?

The pharmaceutical forms recorded for this strain are suspension for injection and suspension for injection in a pre-filled syringe. The route of administration is intramuscular injection.^[1] In the trials, the vaccines containing this strain are given as 0.5 ml injections.^[1]–[5]

What do the clinical trials show?

Five clinical trials involve this strain. The strain is the test substance in three trials and a comparator in one trial.^[1]

The largest trial is a Phase 3 study with 57,925 participants aged 65 years and older. It compares Fluad and Fluad Quadrivalent against a non-adjuvanted influenza vaccine, measuring the first occurrence of RT-PCR-confirmed influenza due to any influenza A or B virus from 14 days after vaccination until the end of the influenza season.^[5]

Another Phase 3 trial, completed, enrolled 6,300 adults aged 50 years and older. It assessed lot-to-lot consistency of a high-dose cell-derived quadrivalent influenza vaccine (aQIVc HD) and compared its immunogenicity against vaccines containing the B/PHUKET/3073/2013-like strain, measured by hemagglutination inhibition (HI) assay at day 29.^[1]

Two completed Phase 2 trials studied co-administration of adjuvanted influenza vaccines with COVID-19 vaccines. One enrolled 120 adults aged 65 and older and measured serum neutralizing antibody responses to SARS-CoV-2 variants of concern at days 0, 10, 28 and 90.^[4] The other enrolled 300 adults older than 65 years and measured solicited local and systemic reactions through day 7, unsolicited adverse events, serious adverse events and adverse events of special interest.^[2]

A Phase 3 trial on avian influenza enrolled 300 participants and measures seroconversion proportion three weeks after the second dose, assessed by microneutralization test.^[3]

What side effects are known?

The homeopathic product label for Influenzinum, which contains the B/PHUKET/3073/2013 hemagglutinin antigen, advises stopping use and asking a doctor if symptoms persist for more than 3 days or worsen. The label states the product has not been evaluated by the FDA for safety or efficacy.^[6] No side effect data specific to the B/PHUKET/3073/2013-like strain as a vaccine component are provided in the trial records.