How Do Mrna Coronavirus Vaccines Work Science With Sam Explains
Since the first vaccine was developed in 1796, vaccinations have been phenomenally successful at preventing infectious diseases, and wiping out some altogether.
The latest video in our new YouTube series, Science with Sam, explains how vaccines work by training your immune system to recognise viruses and bacteria. Ever wondered how flu vaccines are made or why you need a new one every year? Click play to find out.
We also take a look at the unprecedented worldwide effort to develop a vaccine for the coronavirus, and consider the challenges involved in making, testing and distributing covid-19 vaccines.
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The Myth Of Antigenic Overload
An important parental concern is that vaccines might overwhelm their childrens immune systems. In a telephone survey in the USA, 23% of parents agreed with the statement Children get more immunizations than are good for them, and 25% indicated that they were concerned that their childs immune system could be weakened by too many immunizations. However, there is ample evidence to disprove these beliefs. Although the number of vaccines in immunization programmes has increased, the total number of antigens has actually decreased from more than 3,200 to approximately 320 as a result of discontinuing the smallpox vaccine and replacing the whole-cell pertussis vaccine with the acellular vaccine,. Vaccines comprise only a small fraction of the antigens that children are exposed to throughout normal life, with rapid bacterial colonization of the gastrointestinal tract after birth, multiple viral infections and environmental antigens. Moreover, multiple studies have shown that children who received vaccinations had a similar, or even reduced, risk of unconnected infections in the following period,,,. Looking at children who presented to the emergency department with infections not included in the vaccine programme, there was no difference in terms of their previous antigen exposure by vaccination.
Is Is Better For My Child To Get The Disease Naturally
No. The only way to get the disease naturally would be through infection with the bacteria or virus that causes the disease. This would pose a serious risk to your childs health, potentially making them very ill and causing long-term effects. Some diseases, such as measles and meningitis, can also be fatal. Natural infection also enables the disease to spread from your child to those around them, increasing the risk of others getting ill. Vaccination allows your child to build up immunity in a safe and controlled environment without becoming ill with the disease and passing it to others.
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Evolution Of Vaccine Science
Edward Jenner is duly credited with providing the first scientific description of vaccination when he published his monograph An Inquiry into the Causes and Effects of the Variolae Vaccinae in 1798. Although, notably, variolation was practiced in China, India, and Turkey for centuries before it was introduced to the West by Lady Mary Montaguethe wife of the British ambassador to the Ottoman court. Vaccination itself, which involved injecting material from cowpox vesicles to healthy individuals was first demonstrated by Benjamin Jesty, a Yetminster, England farmer, approximately a quarter century before Jenners vaccine demonstration.
While Jenners technique for vaccination was relatively widely used throughout the nineteenth century, vaccination was conducted from person-to-person or animal-to-animal, i.e., material from a vaccinated individual was used to vaccinate another individual.
The modern science of vaccination was developed by Louis Pasteur. Pasteur developed vaccines in the laboratory using the same agent that caused the disease, starting with chicken cholera vaccine. In 1879/1880, Pasteur used a culture of chicken bouillon to develop a chicken cholera vaccine that could be produced in a lab. Five years later, he followed this with a human rabies vaccine.
Booster Shots And Additional Primary Doses
A booster shot is for people who built enough protection after completing their primary vaccine series, but then that protection decreased over time. Everyone ages 16 years and older who is fully vaccinated can get a booster. Learn more about getting a COVID-19 vaccine booster shot.
An additional primary dose is for people who did not build enough or any protection from their primary vaccine series. This appears to be the case for some immunocompromised people who received Pfizer-BioNTech or Moderna COVID-19 vaccines.
Currently, moderately or severely immunocompromised people ages 18 years and older who completed their Moderna vaccine primary series should plan to get an additional primary dose 28 days after receiving their second shot. People ages 12 years and older who completed their Pfizer-BioNTech vaccine primary series should also plan to get an additional primary dose 28 days after receiving their second shot.
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When Facts Wont Suffice
While it may be hard for us to imagine, facts are simply not enough to convince vaccine deniers of their safety or efficacy. Time and again, article after article has shown that there is indeed no significant link between vaccine administration and incidence of autism, for example. The most recent study of studies examined data from some 1.2 million children to draw these conclusions , while the original conclusion from the infamous Wakefield study was based on data from only a handful of self-reported cases. I would cite that article as well if it hadnt been retracted for numerous reasons.
How Does A Vaccine Introduce A Pathogen Without Making You Sick
Scientists have developed several ways to introduce a pathogen to the immune system without risking disease. One methodwhats known as an inactivated vaccineexposes the bacteria or virus to certain chemicals, radiation, or heat to kill it, so that it is no longer able to infect human cells this deactivated pathogen is whats in the vaccine. Alternatively, scientists might weaken a pathogen so that it is still able to infect cells but without causing sickness these are known as live or attenuated vaccines.
Both methods have been used safely and effectively for several decades to protect people against a variety of diseases that were once common and serious. Examples include the Salk polio vaccine, as well as vaccines against measles, mumps, and rubella, among others.
Both inactivated and live attenuated vaccines for COVID-19 are currently under development worldwide. Sinovac Biotech, a company in China, produced an inactivated vaccine that has been approved there for emergency use, and several other inactivated vaccines are at various stages of development in China, India, and elsewhere. But one downside to inactivated viral vaccines is that they require considerable quantities of virus to be produced, which is a slow process.
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How Do Vaccines Work
This article is part of a series of explainers on vaccine development and distribution. Learn more about vaccines from how they work and how theyre made to ensuring safety and equitable access in WHOs Vaccines Explained series.
Germs are all around us, both in our environment and in our bodies. When a person is susceptible and they encounter a harmful organism, it can lead to disease and death.
The body has many ways of defending itself against pathogens . Skin, mucus, and cilia all work as physical barriers to prevent pathogens from entering the body in the first place.
When a pathogen does infect the body, our bodys defences, called the immune system, are triggered and the pathogen is attacked and destroyed or overcome.
Vaccination Works But It Is Not A Guarantee
If you get a vaccine, theres still a chance you could get the virus. But this is true with natural infections too! People can get infected twice with the same virus.
A vaccines efficacy rate tells you how well a vaccine protects you from infection. Its measured by comparing how many people got sick after having the vaccine vs. those who didnt get vaccinated. Most vaccines are 90+% effective. Some are lower. The flu vaccine, for example, is usually between 40 and 60% effective. This rate is lower than most in part because a lot of people who get the flu vaccine are older. As you age, your immune system doesnt work as well. Its also because the flu is complicated. There are lots of strains going around, and they change with each season. But that doesnt mean you should skip the vaccine! You can think of it like a seat belt: its not guaranteed to save you from injury, but it improves your chances.
Even a partially effective flu vaccine saves thousands of lives each year in the US. Plus, even if you get infected after having the vaccine, the symptoms are most often mild. Thats because a vaccine can sometimes give partial protection. Immunity isnt like a binary, on/off switch. Its more like a dimmer.
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How Does Vaccination Work
The immune system is a network of cells, tissues and organs that work together to help fight off infection from harmful bacteria or viruses. When a disease-causing agent, such as virus or bacteria, invades your body, your immune system recognises it as harmful and will trigger a response to destroy it.
One of the ways your immune system fights off infection is by creating large proteins known as antibodies. These antibodies act as scouts, hunting down the infectious agent, and marking it for destruction by the immune system. Each antibody is specific to the bacteria or virus that it has detected and will trigger a specific immune response. These specific antibodies will remain in the immune system after the infection has gone. This means that if the same disease is encountered again, your immune system has a memory of the disease and is ready to quickly destroy it before you get sick and any symptoms can develop.
Different Cells Different Symptoms
You probably know that no two viruses make you sick the same way. It goes back to which cell types they infect.
For example, rhinovirus infects airway cells. So you sneeze and have a runny nose. Norovirus infects cells in your gut. So you get an upset stomach, nausea, and diarrhea.
Many symptoms arise because copying the virus harms your cells. A cells resources get used up as it pumps out tons of new viruses, so it cant do its regular job very well. Most viruses eventually kill their host cells, causing you pain and swelling in the area.
With some viruses, you feel symptoms in places outside of where the virus infects. For example, influenza A only infects your airways. But if youve ever had the flu, you know it makes you feel bad all over. People often have airway symptoms combined with headaches, fever, sore muscles, and low energy.
These symptoms are side effects from your immune system as it kills the virus. Thats why the symptoms happen with many illnesses.
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Immunisation Protects Against Infectious Disease
The purpose of immunisation is to prevent people from getting sick. It helps to protect people against the complications of becoming ill, including developing chronic diseases, cancer, and death.68
Vaccines work by stimulating the bodys defence mechanisms to provide protection against infection.
Vaccines can sometimes produce a stronger, longer-lasting protective response compared to immunity from a natural infection.
Vaccines create immunity without causing disease. Disease can lead to serious complications, which is why vaccination is a safer way to develop immunity.
Vaccines work by stimulating the bodys defence mechanisms to provide protection against infection and illness. These defence mechanisms are collectively referred to as the immune system. Vaccines mimic and sometimes improve the protective response normally mounted by the immune system after infection. The great advantage of immunisation over natural infections is that immunisation has a much lower risk of harmful outcomes.24,915
Where Vaccine Science Is Headed
Systems vaccinology incorporates systems biology approaches using multidisciplinary high-dimensional datasets to better inform vaccinesfrom the discovery phase of design of the vaccine all the way to predicting responses in clinical trials and improving on implementation strategies. Systems vaccinology has been applied to multiple vaccines, including influenza viruses and yellow fever, and revealed an unexpected correlation between gene signatures and vaccine efficacy . Further, the systems serology approach has been applied to HIV-1 vaccines that reveal potential antibody correlates of protection.
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What Are Vaccines Made Of
Each vaccine will be made up of slightly different ingredients depending on the disease it is targeting. The active ingredient in a vaccine is a very small amount of the killed, greatly weakened or broken-down parts of the bacteria or virus you are vaccinating against. Vaccines also contain small amounts of preservatives and stabilisers, such as sorbitol and citric acid. These can already be found in the body or in food usually in much larger quantities than the amount used in a vaccine. However, the most abundant ingredient in a vaccine is water.
Some vaccines also contain aluminium usually in the form of aluminium hydroxide. Aluminium is found naturally in nearly all food and drinking water and is used in vaccines to strengthen and prolong the immune response they generate.10 The amount of aluminium in vaccines is extremely small and a recent study found that, in an infants first year of life, the total amount of aluminium in both vaccines and food is less than the weekly safe intake level.11
Immunisation is a proven tool for controlling and eliminating life-threatening infectious diseases and is estimated to avert between 2 and 3 million deaths each year – World Health Organization
The Body’s Natural Response
A pathogen is a bacterium, virus, parasite or fungus that can cause disease within the body. Each pathogen is made up of several subparts, usually unique to that specific pathogen and the disease it causes. The subpart of a pathogen that causes the formation of antibodies is called an antigen. The antibodies produced in response to the pathogens antigen are an important part of the immune system. You can consider antibodies as the soldiers in your bodys defense system. Each antibody, or soldier, in our system is trained to recognize one specific antigen. We have thousands of different antibodies in our bodies. When the human body is exposed to an antigen for the first time, it takes time for the immune system to respond and produce antibodies specific to that antigen.
In the meantime, the person is susceptible to becoming ill.
This means that if the person is exposed to the dangerous pathogen in the future, their immune system will be able to respond immediately, protecting against disease.
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Prevention Of Infection Versus Disease
In the case of the current pandemic of the virus SARS-CoV-2, a vaccine that prevents severe disease and disease-driven hospitalization could have a substantial public health impact. However, a vaccine that could also block acquisition of the virus, and thus prevent both asymptomatic and mild infection, would have much larger impact by reducing transmission in the community and potentially establishing herd immunity.
How These Vaccines Work
The body normally produces T-lymphocytes and B-lymphocytes types of white blood cells a few weeks following immunization. As a result, a person might become infected with the virus that causes COVID-19 either before or shortly after immunization and become ill as a result of the vaccine failing to give adequate protection.
The process of establishing immunity following vaccination can sometimes induce symptoms such as fever. These symptoms are typical and indicate that the body is strengthening its defenses.
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Viral Proteins Only Unlock Specific Cells
A virus cant spread to just any cell. Each type of virus has surface proteins that fit only with certain parts on the host cell surface.
And not all cells are the same. Your body is made up of thousands of different cell types, each with its own mix of receptors.
A virus can enter a cell only if the right receptors are there.
How Effective Is Vaccination
Vaccination is extremely effective with most childhood vaccines effective in 85% to 95% of children who receive them.1 It is considered one of our greatest global health achievements and is estimated to save 23 million lives a year.2 Thanks to vaccines, life-threatening diseases that used to be common in young children in the UK, such as diphtheria, whooping cough and polio, are now relatively rare. Looking at the history of vaccine-preventable disease, there is a huge drop in the number of cases of a disease following the introduction of a vaccine against it. If smallpox had not been eradicated, it would cause 5 million deaths worldwide a year!3 Through vaccination, some diseases have even been eradicated completely, for example smallpox.
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Scientific Journal Articles For Further Reading
Jain S, Venkataraman A, Wechsler ME, Peppas NA. Messenger RNA-based vaccines: Past, present, and future directions in the context of the COVID-19 pandemic. Adv Drug Deliv Rev. 2021 Oct 9 179:114000. doi: 10.1016/j.addr.2021.114000. Epub ahead of print. PMID: 34637846 PMCID: PMC8502079.
Verbeke R, Lentacker I, De Smedt SC, Dewitte H. The dawn of mRNA vaccines: The COVID-19 case. J Control Release. 2021 May 10 333:511-520. doi: 10.1016/j.jconrel.2021.03.043. Epub 2021 Mar 30. PMID: 33798667 PMCID: PMC8008785.
Microscopic image of SARS-CoV-2, the virus that causes COVID-19. Spike proteins are seen surrounding the outer membrane of each virus particle.
If These Diseases Are So Rare Why Does My Child Need To Be Vaccinated
All of the diseases that we vaccinate against exist in the world today. Therefore, if your child has not been vaccinated, there is still a risk that they could get the disease and become very sick. We know that decreases in vaccination uptake can result in outbreaks of diseases such as measles.5 Regular vaccination is needed to keep our children healthy, prevent outbreaks from occurring and to eventually eradicate these diseases altogether. Infectious diseases are easily passed from person to person and entire communities can rapidly become infected. If a high enough proportion of a community is protected by vaccination, it makes it difficult for the disease to spread because the number of people who can be infected is so small.
Your immune system is there to protect you by vaccinating your child, you give his/her immune system all the tools it needs to keep them safe from many severe diseases – Meike Heurich-Sevcenco, BSI Vaccine Champion
This type of protection is known as herd immunity and is particularly crucial for some individuals who are unable to receive some vaccines. This may include those that are too young, undergoing certain medical treatment or have a health condition that impairs the function of their immune system . Declines in herd immunity caused by decreasing vaccination rates have recently caused outbreaks of measles and whooping cough in the UK.6,7
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