It is well established that vaccinating most people against infectious diseases can help to protect those who are not vaccinated. This includes people who are too young or too sick to be vaccinated.
For highly-infectious diseases such as measles, the number of people that need to be protected in order to achieve ‘herd immunity’ or ‘community immunity’ is very high. That is why it is recommended that health authorities aim to cover at least 95% of the population with two doses of the MMR vaccine.
But it’s not just measles vaccination that can protect the vulnerable. Vaccination also helps to reduce the spread of flu viruses in communities. This can be especially important for older people.
While people aged 65 and above are a priority risk group for flu vaccination, it is known that vaccination can be less effective in this group. That’s because their ageing immune systems may not respond as strongly as it did when they were younger. [It is still advisable to have the flu vaccine every year if you are in any risk group. Ask your doctor for advice.]
Communities can reduce the chances that older people will be exposed to flu viruses by maintaining high rates of immunisation in people of other age groups. A 2016 study showed that younger adults can protect older adults from flu infection by having their annual vaccine.
The US-based researchers behind the study looked at data from more than 3 million people across eight flu seasons. They found that over 65s were 21% less likely to be diagnosed with flu-related illness if they lived in areas where around one in three adults under 65 were immunised.
Healthy kids, healthy grandparents?
Perhaps the most compelling case for community immunity against flu comes from the UK where children are offered flu vaccination in primary school. The programme began as a relatively small pilot but was then extended to throughout England.
Data from Public Health England shows that the pilot scheme protected children from flu (as expected) but also dramatically reducing illness and hospitalisation in other age groups.
In children aged 5-10 years, GP consultations for flu-like illnesses were down 94% compared to areas where the childhood flu vaccine programme was not in use. Attendance at emergency departments was down 74% while hospital admissions fell by 93%. The need for admission to intensive care units (ICU) and high-dependency units (HDU), was down 76%.
That’s not the end of the story. The most startling results were in other people who lived in areas that benefited from the pilot programme.
In children under five (i.e. not included in the school-based programme), GP consultations with suspected flu fell by 92%; emergency department attendance fell 65%, hospital admissions were down 62% and admission to ICU/HDU was down 61%.
In adults, the figures were also stunning. GP consultations for flu-like illnesses were down 59% in people aged over 17 years; emergency attendances fell 21%; hospital admissions reduced by 34%; and admission to ICU/HDU fell by 46%.
- For every 16 children vaccinated, 1 GP consultation was avoided.
- For every 317 children vaccinated, 1 influenza-related hospitalisation was prevented.
- For every 2,205 children vaccinated, 1 confirmed influenza-related ICU/HDU case was averted.
In addition to the health benefits, the impact on the health system is significant. Major flu outbreaks can put serious pressure on hospitals. If hospital wards – including ICU and HDU beds – are occupied by people suffering serious complications of flu infection, it deprives another seriously ill patient of access to care.
This means that flu vaccination might spare you a trip to the hospital or protect your neighbour from flu – and it might improve your chances of prompt access hospitals with something completely unrelated to flu.
Meningococcal and pneumococcal vaccination has also been shown to provide protection to members of the community who have not been vaccinated. Experts said last year that vaccinating teenagers against bacterial meningitis helps protect teenagers as well as those around them.
Protecting the health system
Vaccines help to protect individuals, communities and reduce the pressure on health systems. But there is one more way in which vaccination is an essential public health tool.
When fewer people get sick with bacterial infections (such as pneumococcal and meningococcal disease), doctors prescribe fewer antibiotics. And, with lower numbers of people presenting to GPs and at hospitals with viral illnesses (such as flu), the inappropriate use of antibiotics also falls.
Prudent use of antibiotics is essential to fighting antimicrobial resistance. If antibiotics become useless, lives will be lost to relatively minor infections and live-saving surgery will become very risky.
That’s why having all your recommended vaccines is good for your health now and in the future – and makes a positive contribution to the wellbeing of those around you.
Which vaccines should you have?
Check out the ECDC Vaccine Schedule to see details of your national immunisation programme – or ask your doctor