So, Why did I get the Flu after receiving the flu shot?

It is possible to get sick after a flu shot for many reasons.

While flu vaccination is a life-saving barrier against the worst effects of influenza, it is far from an all-around guard against respiratory illness. "It's critical to understand that the flu vaccine prepares your immune system to fight the flu, but it doesn't prevent other respiratory illnesses," explains Aitor Aspiazu, an experienced nurse with over 20 years in healthcare, including emergency nursing.

It's common to hear of flu shot recipients with symptoms immediately after receiving their flu jab. You may even have become ill after your last flu vaccination shot.

The flu vaccine has not yet taken full effect.

Flu shots or flu jabs typically take around two weeks to provide complete immunity to the virus, and if you are exposed to influenza during those two weeks (or right before getting the shot), you may still catch the virus. As a result, many individuals who become ill during this period believe it to be a result of the influenza shot, even though flu vaccines cannot directly make you sick.

You have another illness.

Many other illnesses have similar symptoms to the flu, such as COVID-19, the common cold, pneumonia, bronchitis, and stomach flu. These, however, are not affected by the flu shot.

You caught another flu strain.

While unlikely, it is possible to catch another strain of flu that is not protected against by the vaccine. "The flu vaccine is tailored to combat the most prevalent flu strains, but there are many strains out there, and no vaccine can cover them all," Aspiazu remarks. Either way, even if you catch the flu, your symptoms will likely be much weaker than if you had never been vaccinated.

You are an older adult.

All individuals over 65 are considered to be at a much higher risk of contracting the flu and should be vaccinated yearly. "During my time in emergency departments, I've witnessed numerous cases where elderly patients ended up in intensive care due to complications from the flu," Aspiazu recalls, emphasising the importance of vaccination.

While the flu vaccine begins to lose effectiveness among older age brackets, flu shots can prevent anywhere from 25 to 53% of hospitalisations due to influenza or pneumonia.

It’s important for seniors to get a vaccine specifically designed to elicit a stronger immune response, as their systems are less responsive to standard immunisation. Although there's a particular enhanced quadrivalent vaccine tailored for those aged 65 and over, in the absence of this option, other standard quadrivalent influenza vaccines remain a safe and effective alternative for providing protection.

A word from Corporate Care

In an era where misinformation can spread as virulently as the flu itself, it's natural to question the efficacy of the vaccine if you or someone you know has fallen ill despite vaccination. "It’s crucial to look at the bigger picture and the evidence-based benefits of flu vaccination as part of our broader public health practices," Aspiazu recommends.

Corporate Care understands the importance of accurate, trustworthy health information. We urge everyone to seek guidance from reputable sources regarding the flu vaccine—this includes consulting with your GP, practice nurse, or pharmacist, who can provide tailored advice for your health needs.

Consistently getting your annual flu shot remains a sound decision to protect not just yourself but also the community around you, except in cases where it may be contraindicated for medical reasons.