Four giant lorries roll into the loading docks at Seqirus’ Liverpool vaccine factory every morning like clockwork. On board, a precious cargo — 575,000 chicken eggs in which lies the seasonal security of the nation.

This daily delivery is the crucial first step in creating the flu vaccine that will protect the public and prevent the NHS from being overwhelmed by flu and Covid-19 – and the Mail is the first to see inside the factory in the center of everything.

This winter threatens to be the worst flu season in years, with up to 60,000 deaths predicted due to reduced flu immunity and a potential third wave of Covid could derail an already weakened health service.

Professor Jonathan Van-Tam, England’s deputy chief medical officer, warned this week that the flu poses a ‘significant health risk’ as it will circulate with Covid-19 at the same time as cold weather causes an increase in the number of people mingling inside.

The eggs are washed, sorted and incubated in a series of 37 chambers each housing 172,000 fertilized eggs. They are kept under strictly controlled conditions for 11 days to create the perfect environment for a virus to reproduce. The eggs are stored on racks that change the angle of inclination every hour and remain at a precise temperature of 37.5c (99.5f) and 65% humidity – the ideal conditions for developing their embryos .

The eggs are then ready for the production line, which scans 132 eggs at a time and rejects those that are infertile ¿45,000 a day¿ before being pricked with a needle containing 0.2ml of ¿working seed¿, a solution that contains active influenza virus, which has been grown in a laboratory.  After that, the flu virus begins to multiply in the shell

The eggs are then ready for the production line, which scans 132 eggs at a time and rejects those that are infertile – 45,000 a day – before being pricked with a needle containing 0.2ml of “working seed”, a solution that contains active influenza. virus, which was grown in the laboratory. After that, the flu virus begins to multiply in the shell

Imperfections are avoided throughout the process by randomly examining eggs in a process called

Imperfections are avoided throughout the process by randomly examining eggs in a process called “candling”, in which experts use ultraviolet probes to check whether an egg is still fertile or not. Infertile eggs are discarded as they are discovered

After being incubated for 72 hours, the eggs are 'blast chilled' to ensure that the embryo stops growing.  Virus-filled eggs now join a harvesting line, where a huge machine uses a blade to slice off the top of each eggshell.  Probes extract some of the clear fluid from inside the egg, known as allantoic fluid - which now contains thousands of copies of the flu virus

After being incubated for 72 hours, the eggs are ‘chilled’ to ensure the embryo stops growing. Virus-filled eggs now join a harvesting line, where a huge machine uses a blade to slice off the top of each eggshell. The probes extract some of the clear fluid from inside the egg, known as allantoic fluid – which now contains thousands of copies of the flu virus

Salvation comes in a small syringe containing 0.5ml of vaccine which begins its journey to the patient at an 18-acre factory in a hinterland of factories and warehouses south of Liverpool.

At peak production, it has 6.1 million eggs in various stages of vaccine development, with its 650 employees working around the clock on the flu frontline.

Fertilized chicken eggs are an ideal medium for cultivating the virus strains that are the vital components of an effective vaccine.

At the Seqirus factory, they have refined production to such a level that it will send up to 30 million doses this year to immunize the UK.

Everyone over 65 gets egg-based vaccines because they can carry the adjuvant that promotes a better immune response. Vegans, however, can request cell-generated bites.

“The scale is staggering,” says Alan Collins, process manager for the primary incubation unit.

“Every part of the process must work perfectly to ensure that we can provide enough vaccine to keep the nation safe. It’s a complex and demanding production chain, but I love coming to work every day because we are helping to protect lives.

Seqirus recently invested £50 million in production facilities and hired 120 new employees.

The virus is then deactivated using formaldehyde and the solution is purified using a centrifuge.  The remaining solution contains the viral antigen.  This triggers a human immune response to infection without causing disease.  Seqirus produces four strains of the virus, identified by the World Health Organization in February, and mixes them to form a quadrivalent vaccine (above) to protect patients against the four different strains of the flu virus

The virus is then deactivated using formaldehyde and the solution is purified using a centrifuge. The remaining solution contains the viral antigen. This triggers a human immune response to infection without causing disease. Seqirus produces four strains of the virus, identified by the World Health Organization in February, and mixes them to form a quadrivalent vaccine (above) to protect patients against the four different strains of the flu virus

The complete vaccine solution is collected in giant bags of 500 liters.  This sterile machine then fills the syringes at high speed

The complete vaccine solution is collected in giant bags of 500 liters. This sterile machine then fills the syringes at high speed

The solution is measured and put into 0.5ml syringes before the vaccine batches are carefully checked by workers at the production facility

The solution is measured and put into 0.5ml syringes before the vaccine batches are carefully checked by workers at the production facility

The final product is distributed to doctors and pharmacists across the country

The final product is distributed to doctors and pharmacists across the country

“We are subject to quality control at every stage,” explains John Riley, head of the formulation process.

“Every 500 liter batch we produce contains 900,000 vaccines, that’s 900,000 lives that we are protecting and we don’t want anything to go wrong.”

Raja Rajaram, Head of Medical Affairs at Seqirus, adds: “This is an important flu season and uptake of the vaccine will be key to ensuring the NHS is not overwhelmed this winter.”

“We hardly had any flu last year – but now that we’ve been freed from the lockdowns, we mingle more freely with people returning to the office and starting to travel. The vaccine will have a huge role to play in reducing the burden on the NHS.

The flu vaccine can be given at the same time as a Covid booster.

Public Health England is aiming to break its record coverage of 80.9% of over-65s last winter to 85% this season in the UK’s biggest ever flu vaccination programme.

The jab is also offered to people over 50 and young children.

Millions of people will get their shots this month when flu season begins – but many won’t know that the flu vaccination program owes its success to the humble egg.

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