Ever wondered how your body builds up defences against dangerous... Show more
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31 Dec 2025
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Ever wondered how your body builds up defences against dangerous... Show more






You're about to discover one of medicine's most powerful tools for keeping people healthy. Vaccination has saved millions of lives by preventing diseases that used to kill or seriously harm people regularly.
Think of vaccines as a training course for your immune system. They teach your body how to recognise and fight specific diseases without putting you through the actual illness.
Quick Fact: Vaccines have reduced diseases like polio, measles and tetanus by an incredible 99%!

Before diving into the science, let's tackle the main questions you'll need to answer about vaccines. Understanding what they are, how they work, and which diseases they prevent will give you a solid foundation.
You'll also need to know exactly how your body's natural defence system responds to infections. This knowledge helps explain why vaccines are so effective at protecting us.
The most common vaccines you've probably heard of include MMR (measles, mumps, rubella), flu jabs, and HPV vaccines.

Here's the clever bit: a vaccination contains a small amount of dead or inactive pathogens that can't make you ill, but still trigger your immune system to respond. Your body's lymphocytes (white blood cells) detect antigens on these harmless pathogens and produce antibodies to destroy them.
The brilliant part is that your lymphocytes remember these antigens for years. If the real, dangerous pathogen ever enters your body, your immune system recognises it instantly and produces antibodies much faster than the first time.
This rapid response destroys the pathogen before it can make you seriously ill. That's how immunity works - you become protected against that specific disease.
Remember: Your body treats inactive pathogens in vaccines exactly like live ones, but without the risk of getting sick!

Vaccines bring massive benefits to society, but like any medical treatment, they're not perfect. The spread of communicable diseases can be controlled effectively when enough people get vaccinated.
Herd immunity kicks in when over 85% of a population is vaccinated. This protects even people who can't have vaccines, because there aren't enough unvaccinated people for diseases to spread easily.
However, vaccines occasionally don't work for some individuals. A small number of people might experience side effects like swelling, nausea, or fever - though these are usually mild and temporary.
Key Point: The benefits of vaccination massively outweigh the risks for the vast majority of people.

Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Ever wondered how your body builds up defences against dangerous diseases without actually getting sick? Vaccination is like giving your immune system a practice run, training it to recognise and fight off real infections before they can make you seriously... Show more

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
You're about to discover one of medicine's most powerful tools for keeping people healthy. Vaccination has saved millions of lives by preventing diseases that used to kill or seriously harm people regularly.
Think of vaccines as a training course for your immune system. They teach your body how to recognise and fight specific diseases without putting you through the actual illness.
Quick Fact: Vaccines have reduced diseases like polio, measles and tetanus by an incredible 99%!

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Before diving into the science, let's tackle the main questions you'll need to answer about vaccines. Understanding what they are, how they work, and which diseases they prevent will give you a solid foundation.
You'll also need to know exactly how your body's natural defence system responds to infections. This knowledge helps explain why vaccines are so effective at protecting us.
The most common vaccines you've probably heard of include MMR (measles, mumps, rubella), flu jabs, and HPV vaccines.

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Here's the clever bit: a vaccination contains a small amount of dead or inactive pathogens that can't make you ill, but still trigger your immune system to respond. Your body's lymphocytes (white blood cells) detect antigens on these harmless pathogens and produce antibodies to destroy them.
The brilliant part is that your lymphocytes remember these antigens for years. If the real, dangerous pathogen ever enters your body, your immune system recognises it instantly and produces antibodies much faster than the first time.
This rapid response destroys the pathogen before it can make you seriously ill. That's how immunity works - you become protected against that specific disease.
Remember: Your body treats inactive pathogens in vaccines exactly like live ones, but without the risk of getting sick!

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Vaccines bring massive benefits to society, but like any medical treatment, they're not perfect. The spread of communicable diseases can be controlled effectively when enough people get vaccinated.
Herd immunity kicks in when over 85% of a population is vaccinated. This protects even people who can't have vaccines, because there aren't enough unvaccinated people for diseases to spread easily.
However, vaccines occasionally don't work for some individuals. A small number of people might experience side effects like swelling, nausea, or fever - though these are usually mild and temporary.
Key Point: The benefits of vaccination massively outweigh the risks for the vast majority of people.

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the fundamentals of vaccines, including their definitions, mechanisms of action, and historical significance. This study note covers key concepts such as herd immunity, the immune response, and the contributions of Edward Jenner. Ideal for GCSE Biology students, it includes model-answered questions and highlights the advantages of vaccination in disease prevention.
Biology Paper 1 topic - detailed mind map of full topic areas within infection and response (biology combined higher GCSE)
Explore the mechanisms and differences between antibiotics and painkillers. This summary covers the development of penicillin, the treatment of bacterial versus viral infections, and the importance of new antibiotics in combating antibiotic resistance. Ideal for students studying infectious diseases and pharmacology.
Explore the comprehensive stages of drug development, including preclinical testing and clinical trials (Phases I-III). Understand the importance of safety, efficacy, and dosage determination in drug trials, with examples like aspirin and penicillin. Ideal for GCSE AQA Biology students studying Infection and Response.
Explore key concepts of photosynthesis and respiration, including the processes, factors affecting rates, and the role of metabolism in energy transfer. This summary covers essential topics like aerobic and anaerobic respiration, the circulatory system, and the immune response, providing a comprehensive overview for AQA Combined Science Higher Biology Paper 1. Ideal for quick revision and understanding of biological life processes.
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user