Flu Season: Vaccine Myths Debunked

Article | Dr Toni Hazell, GP, Freelance Medical Writer, Blogger and Editor

Influenza (flu) is an acute respiratory illness caused by a virus. During the flu season (in the winter months), flu vaccination is offered on the NHS. This year it is being offered to all those aged over 50, as well as younger adults who have medical conditions, and some children.

We use various things to mark the passage of time – for many GPs, the annual flu vaccination season is a rite of passage. Vaccination against flu has been available since the 1960s, with the vaccine being offered to children from 2013- 14 onwards. Each practice does things differently – at my practice, we do an annual Saturday morning in September in which we vaccinate several hundred people; it has become quite the social event for some of our patients!

However, you are likely to come up against the same issues time and time again, so I’ll now try and bust some myths about flu vaccination.

Can the Influenza and COVID-19 Booster Vaccines be Administered Together?

Vaccination has been on our minds since the COVID-19 pandemic – who would have thought that the public would take such an interest in the brand of a vaccine being offered to them? With the over 50s being offered both a COVID-19 booster and a flu vaccine this winter, the question of co-administration is bound to come up.

At the start of the COVID-19 vaccine programme, it was advised not to give the two vaccines together, but that was precautionary rather than based on any solid evidence.

We now know that this is safe [3] and the Green Book [4] (the goto reference for any vaccination questions in the UK) says that inactivated influenza vaccines can be given at the same time as other vaccines.

However, this should ideally be in different limbs, but at a push in the same limb, at least 2.5cm apart. All flu vaccines offered to adults in the UK are inactivated. The live attenuated influenza vaccine (LAIV) offered to children can also be given at the same time as other live or inactivated vaccines [4].

Are there any Exceptions to this?

The only exception for this is when patients who are being given an adjuvanted flu vaccine (generally offered to those aged 65 or over) also want to have their shingles vaccine on the same day and are being offered the Shingrix brand. There is an absence of data and so the Green Book [4] advises that, if possible, these two vaccines be separated by at least seven days [5] .

This isn’t an issue for other brands of shingles, or for non-adjuvanted flu vaccines. However, if there is a risk that the gap will lead to the patient being lost to follow-up, or a need for rapid protection, we can consider co-administration.

What are the Cultural and Religious Considerations?

The UK is a very multicultural nation and those of us who work in areas with large communities of different religions, particularly in areas of orthodox observance, will be used to Jewish and Muslim patients asking for an alternative to LAIV for their children, on the grounds that LAIV contains porcine gelatine.

The reality is that porcine gelatine is used as a stabiliser in the manufacturing process for LAIV. During manufacture it is broken down to such an extent that no porcine DNA can be detected in the actual vaccine [6] . Many patients will be happy for their child to have LAIV (which produces higher immunity in children than the injectable vaccine, as well as not needing a painful injection).

It is particularly helpful if you can back up your advice with patient-friendly information such as that available from the Muslim Council of Britain [7] , the Kashrus, Medicines Information Service [8] , and Public Health England [9] .

For those parents who are still unhappy with LAIV, the position has changed over the years – previously we could only offer those in an at-risk group an injectable vaccine, whereas those being vaccinated due to age alone had to rely on herd immunity.

This year it is fine to offer an injectable vaccine as an alternative, usually the cell-based quadrivalent influenza vaccine (QIVc).

Can the Vaccine cause Influenza to be Passed to Others?

Parents may also be concerned that their child will ‘shed’ flu after their live vaccine and that this might be dangerous for an immunocompromised household member. The risks of shedding are a key tenet of the anti-vaccine movement and are usually overemphasised.

The Green Book [4] advises that there have been no reported cases of illness among such contacts of newly vaccinated children in the United States (where LAIV is widely used) and that these children can have the LAIV like their peers.

They sound only the slightest note of caution where the household member is severely immunocompromised and contact is unavoidable (using the example of someone in isolation following a bone marrow transplant), in which case it may be pragmatic to offer an inactivated injectable vaccine instead.

How does the Influenza Vaccine Impact those with Egg Allergies?

Finally, another common misconception of flu vaccines – “I can’t have it, doctor, I’m allergic to eggs”. Some flu vaccines are cultured in a solution containing egg, but the QIVc and recombinant quadrivalent influenza vaccine (QIVr) are egg-free, and most of the egg-grown quadrivalent influenza vaccines (QIVe) have very low amounts of ovalbumin [10] .

Those with an egg allergy can largely be offered vaccination in primary care, the exceptions being the cohort of children who have been admitted to intensive care due to their egg allergy – they should be given LAIV in a hospital setting, due to limited data. Adults in the same situation should be offered an egg-free vaccine in primary care, or, if this is not available, referred to a specialist with a view to hospital vaccination [4] .

Before we know it, the first six months of 2023 will have flown past and we will be contemplating another flu vaccination season, as time marches on.

Dr Toni Hazell

GP, Freelance Medical Writer, Blogger and Editor

Toni is a GP in North London and works for the Royal College of General Practitioners (RCGP) as an eLearning fellow, writing and editing eLearning. She also does similar work for a variety of other organisations and is a regular presenter and chair at GP educational events.

Her blog can be found online at www.tonihazell.co.uk

1. NICE CKS. Immunizations – seasonal influenza. 2022. https://cks.nice.org.uk/topics/immunizations-seasonal-influenza/

2. De Lusignan S, Correa A, Ellis J et al. Influenza vaccination: in the UK and across Europe. BJGP 2016; 66(650): 452 – 3

3. Lacobucci G. Covid and flu: what do the numbers tell us about morbidity and deaths? BMJ. 2021 Oct 14;375:n2514

4. UK Health Security Agency. Influenza: The Green Book, chapter 19. 2022. https://www.gov.uk/government/publications/influenza-the-green-book-chapter-19

5. UK Health Security Agency. The Green Book. Shingles. 2021. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1012943/Green_book_of_immunisation_28a_Shingles.pdf

6. Vaccine knowledge project. Gelatine in vaccines. 2021. https://vk.ovg.ox.ac.uk/vk/gelatine

7. Muslim Council of Britain. Position on flu vaccines. 2019. https://mcb.org.uk/mcb-updates/position-on-flu-vaccines

8. Kashrus and medicine information service. Letter about vaccines with a porcine element. 2020. https://www.hackneyandcityhealthvisiting.nhs.uk/content/uploads/Vaccine-letter-from-Rabbi-Adler.pdf

9. Public Health England. The children’s flu vaccination programme, the nasal flu vaccine Fluenz and porcine gelatine Your questions answered. https://www.falknerhouse.co.uk/brechin-place/wp-content/uploads/2016/11/QA-Porcine-Gelatine-Content.pdf

10. All influenza vaccines marketed in the UK for the 2022 to 2023 season. April 2022. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1068455/UKHSA-2022-ovalalbumin-table-2022-2023.pdf