Vaccinators should leave a seven-day gap between the flu jab and the Novavax Covid-19 vaccination, the UK Health Security Agency (UKHSA) has said.

Guidance for healthcare providers said that other Covid-19 and influenza vaccines may be administered at the same time ‘where operationally advantageous’.

The guidance refers to a 2022 study that revealed that when the Novavax Covid-19 vaccine was co-administered with the inactivated influenza vaccine, the antibody response to Covid-19 was somewhat reduced.

UKHSA has said that ‘the clinical significance of this is unclear’ but has said that the Novavax Covid-19 vaccine should be given at least seven days apart from the influenza vaccine.

The guidance also refers to a UK study of co-administration of AstraZeneca and Pfizer BioNTech Covid-19 vaccines with inactivated influenza vaccines, which did not have the same results. When these vaccines were administered at the same time as the influenza vaccine, the study found ‘acceptable immunogenicity and reactogenicity’.

UKHSA advised that patients receiving the AstraZeneca or Pfizer Covid-19 vaccines alongside the influenza vaccine should be informed about the likely timings of any potential side effects relating to each vaccine.

It said that if the vaccines are not given together, they can be administered at any interval, although separating the vaccines by a day or two will avoid confusion over systemic side effects.

Many pharmacies are offering both the flu jab and Covid-19 booster vaccination services this winter. LloydsPharmacy has predicted a 20% increase in flu jab bookings compared to last year.

In August, NHS England advised healthcare professionals that the three mRNA vaccine types should be prioritised but Novavax can be used off-label as a booster dose for over-18s ‘in exceptional circumstances’.

It also said that in line with’ a recommendation from the JCVI, it would ‘deploy a single type of vaccine’ – the Moderna Omicron-targeting bivalent vaccine – in the majority of adult cases, for simplicity of delivery.

In September, Pfizer’s new bivalent vaccine targeting the Omicron Covid variant was added to the autumn booster campaign.

In August, the Novavax Covid-19 vaccine was approved by the Medicines and Healthcare products Regulatory Agency (MHRA) for use in 12-17-year-olds. It was already approved as a two-dose schedule for over-18s.

Novavax uses recombinant protein-based technology, similar to that already in use in hepatitis B and other vaccines, and is tipped as a replacement for Pfizer and Moderna vaccines in next year’s campaign due to its lower cost.