How Effective is the Annual Flu Jab? | We Look at the Facts | FluCamp

The flu jab has encountered some controversy during its time in circulation. However, recent research suggests that some of these rumoured negative effects may in fact not be true – and actually, the opposite might apply.

According to an article on WebMD, the notion that people who receive the flu jab every year are weakening their immune system is false – and, in fact, research has shown that an annual vaccination could be tied to stronger immune cell activity.

The Annual Flu Jab: How do we know it’s effective?

Each year studies are performed to determine how well Flu Jabs are protecting members of the public from influenza. While each year varies in the strain of influenza circulating and the effectiveness of the vaccine at fighting the specific strains, studies show that flu vaccinations reduce the risk of infection by between 40% to 60%.

Not only do Flu Jabs prevent infection but we can also see how effective they are by looking at the number of serious cases of flu and the number of hospitalisations. With the years in which flu jabs are more effective showing lower rates of hospitalisations and severe cases, in those that are vaccinated.

Public health researchers measure how well flu vaccines work through different kinds of studies. In “randomized studies,” flu vaccination is randomly assigned, and the number of people who get flu in the vaccinated group is compared to the number who get flu in the unvaccinated or placebo group. The effects of vaccination measured in these studies is called “vaccine efficacy.”. At FluCamp we work to find how effective some vaccines are at preventing flu by measuring the amount of virus found within an infected volunteer who has been vaccinated vs an infected volunteer who has not been vaccinated.

Vaccine Effectiveness: How Well Do Flu Vaccines Work? | CDC

Monitoring immune health

Rebecca Cox, from the University of Bergen’s department of clinical science, led a study where the team tracked the immune system health of 250 health care workers. She noted that although the flu jab has been in use for more than half a century, studies into the long-term effects on the health of recipients’ immune systems have been few and far between.

Of the people involved, some had received the flu jab every year since 2009, while others got the jab in 2009, then skipped it between 2010 and 2013. That’s where the results got interesting. According to the article: “Immune system antibodies that showed activity against the flu “persisted above the protective levels in [the] repeatedly vaccinated adults,” the team reported.

Long-term Maintenance of the Influenza-Specific Cross-Reactive Memory CD4+ T-Cell Responses Following Repeated Annual Influenza Vaccination – PubMed (

“Specifically, immune system CD4 and CD8 T-cells — which target viruses — had more disease-fighting capability “after multiple annual vaccinations” than those in people who didn’t get the yearly flu shot, the investigators found.”

Encouraging evidence

Dr. Len Horovitz, an expert on influenza and a pulmonary specialist at Lenox Hill Hospital in New York City, reviewed the findings from the Norwegian research project, and found that they make the case for annual vaccinations even stronger. “The study shows that those that are annually vaccinated do not lose their second line of defense [against viruses],” he explained.

Dr. Debra Spicehandler, an infection expert, agreed with the benefits of a flu jab, explaining that yearly protection is important for preventing the flu, and that the annual vaccines are carefully tailored to protect against whatever specific viruses are prevalent at a certain time of year.

Flu vaccines in the UK

The success of the flu jab is something that the NHS, and many UK medical professionals, have long vouched for. According to the NHS, the flu vaccine is “the best protection we have against an unpredictable virus that can cause unpleasant illness in children and severe illness and death among at-risk groups, including older people, pregnant women and those with an underlying medical health condition.”

The annual flu jab is first considered in February of each year, when the World Health Organisation assesses the strains that are likely to come into play during the colder months. Once they decide on the types to be included, production typically starts in May – with most people getting the jab in the UK between October and November.

If you’re interested in helping us find out more about the way flu affects the human body, and what we can do to eradicate it, find out about becoming one of our everyday heroes by taking part in a FluCamp clinical trial.

< >

Apply now and get up to £4,400 in compensation

An average clinical trial length is 11 – 14 days. To apply for FluCamp please complete our online form. We'll call you back within 24 hours to explain the next steps so you can decide if it's for you.