According to the World Health Organization (WHO), a vaccine is a biological preparation that trains your immune system to create antibodies against a particular infectious disease. More information here.

Vaccines "train" the body to defend itself against microorganisms, such as viruses or bacteria. Then, when the virus tries attacking, our immune system already knows how to fight it. More information here.

According to the World Health Organization, vaccines protect against many diseases, including: Diphtheria Pertussis Varicella Tetanus Cervical cancer Pneumonia Polio Influenza Hepatitis B Covid-19

Scientists have developed different ways of making efficient vaccines by injecting the antigens without causing the disease. Here are some examples: Live attenuated vaccines (ex. measles, varicella, rotavirus) Inactivated vaccines (ex. polio, hepatitis A, rabies) Subunit/Conjugate vaccines (ex. influenza, pertussis, human papillomavirus) Toxoid vaccines (ex. diphtheria, tetanus) Conjugate vaccines (ex. haemophilus influenzae type B) DNA vaccines (ex. DNA vaccines against herpes are currently in human testing phases) Recombinant vector vaccines (ex. HIV, rabies) RNA vaccines (ex. influenza, cytomegalovirus, HIV-1, rabies, and zika virus - some of them in experimental stages) Check this post for more information about the most common types of vaccines.

The two main types of vaccines are inactivated and live attenuated. Inactivated vaccines are made with inactivated versions of the pathogen or only a specific sequence that produces a spike protein. These cannot cause illnesses because the pathogen is unable to replicate. Live attenuated vaccines include pathogens in their weakest form, meaning that the pathogen could potentially replicate and infect other cells. However, the symptoms will be significantly reduced compared to the severity of the symptoms from the original disease. These vaccines are carefully designed to minimize this risk and to ensure their safety. For more information about the different types of vaccines check out this post.

Yes. Vaccines are very safe. This is because vaccines go through several rigorous tests across multiple phases of trials before their approval for general use. If any side effects were to occur, they are usually minor and temporary. There is however a very low probability that they are severe. In this case, scientists will monitor and treat those patients and improve the vaccine accordingly. For more information, watch our video about how vaccines are created.

No, vaccines do not cause autism. There is a theory known as opioid excess theory, that links bowel disease and autism. Andrew Wakefield used this theory to publish a possible link between the MMR (measles, mumps, and rubella) vaccine and bowel disease in 1998. Therefore linking the vaccine with autism. However, in 2004, it was revealed that Wakefield’s research had ethical violations, fraud, and grave flaws. In fact, in 2010, Wakefield was banned from practising medicine in Britain and his research paper was retracted from the journal. Lastly, this myth is widely spread because children get the MMR vaccine within their first 5 years, which is the same timeframe that most kids get diagnosed for autism. More information about this topic here.

There are several extensive studies that have investigated the relationship between vaccination and allergies, including asthma. For example, between 1991 and 1997, in the United States, a group of scientists studied a large number of children with asthma and found that the risk for asthma was not greater in children who received vaccines compared with children who did not receive these vaccines. In Australia, another group of investigators looked for associations between receipt of vaccines and asthma, eczema, food allergies or allergic rhinitis, and did not find any correlation between the receipt of childhood vaccines and any of these conditions. In conclusion, there is a lot of evidence that suggests vaccines are not related to allergic diseases, including asthma. You can read more information about the different studies done about this topic here.

Microchips are too big to get through the syringe and into the cell. You can read this post for more information about this myth. The ingredient components of a vaccine may include: Antigens (substance that induce an immune response) Adjuvants (substances that enhance the immune response) Antibiotics (inhibit the growth of bacteria) Preservatives and stabilizers (preserve the vaccine until it’s used) For a complete list of ingredients in the mRNA COVID-19 vaccines, check out this post.

Jeffrey Almond, a well-known scientist at Oxford University, who has several scientific publications regarding immunology and vaccines, said that “injecting RNA into a person does nothing to the DNA of a human cell.” More information about this topic here. RNA is not able to get inside the nucleus of cells and is not stable enough under biochemical procedures, so it will be destroyed as soon as the final protein is made. You can read more information about the differences between DNA and RNA here.

Even though the process of creating a vaccine might include human cells, these cells are not able to form a human body on its own - due to the fact that the human body is formed by many different types of cells. Cells are only used to multiply components (ex. mRNA, plasmid, DNA, etc) of the vaccine, however, they are removed to purify the vaccine. Therefore, cells are not injected in the body. For a complete list of ingredients in the mRNA COVID-19 vaccines, check out this post.

People who get vaccinated have lessened or nonexistent symptoms. One example of this is Measles, a highly contagious disease that can lead to ear and lung infections, and brain inflammation. 1 in 1000 infected children could develop brain inflammation, which could end in permanent damage. 1 in 3000 infected children may die from it. Those are scary statistics. However, a single dose of the measles vaccine, given at 12-15 months of age, has an efficacy of around 85-95%. With a second dose, the efficacy is almost 100% (more information here).

Not vaccinating means you have a higher risk of catching and having symptoms of the disease in question. Those symptoms may last for days or weeks, and can sometimes lead to serious complications or death if they are not treated in time. Furthermore, those who do not get vaccinated can spread the disease, and transmission becomes exponential if other people in the community are not vaccinated either.

The CDC has found only 1-2 GBS cases per million that resulted from the flu vaccine. However, CDC also states that "it is more likely that a person will get GBS after getting the flu than after vaccination." Furthermore, it is important to remember that severe illness and death are associated with flu, and vaccines are the best way to prevent it. Lastly, Guillain-Barré syndrome has a better outcome when treatment is started as soon as possible. Therefore, it is important to seek medical advice if you feel a rapid spread of tingling, weakness, or shortness of breath when lying flat.

“Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) are committed to ensuring that all vaccines are as safe as possible. Once vaccines are licensed in the United States, they are continuously monitored through several safety systems and programs.” (CDC, 2021) Additionally, in each country, there are different organizations and agencies in charge of doing similar tasks in terms of vaccine supervision. Examples of this are Health Canada, European Medicines Agency, Comisión Federal para la Protección Riesgos Sanitarios (COFEPRIS) in Mexico, and so on. Those organizations work hard to perform high-quality vaccine safety research and are continuously identifying vaccine adverse events through public health surveillance.

When a person gets vaccinated, this vaccine induces immunity by causing the recipient’s immune system to react against the antigens contained. Local and systemic reactions such as weakness, body ache or fever can occur as part of the immune response. The immune system is using all the body’s energy, making the body feel very weak. In fact, muscles usually hurt because they don’t have enough energy stored to move. Moreover, the body increases its temperature because viruses and bacteria are very unstable and very susceptible to small changes in temperature. By having fever, the body is creating an environment where the pathogen is not able to survive, but without causing any long-term effect for itself. There are also severe side effects that can happen shortly after getting vaccinated. For example, it is important to wait 10-15 minutes after receiving a vaccine in case of an allergic reaction. A successful vaccine keeps even minor reactions to a minimum while producing the best possible immune response.

Besides influenza, other viruses can cause symptoms similar to the flu. The flu vaccine protects against some influenza viruses, but not against other viruses like respiratory syncytial virus (RSV) or rhinovirus - which commonly causes cold symptoms.

This characteristic depends on the vaccine. There are vaccines (like the flu shot) that need to be updated every year to follow the changes of the new variants and others that don’t grant a robust immunity overtime. On the other hand, for example, people vaccinated with the Measles, Mumps, and Rubella (MMR) vaccine are considered protected for life. The efficacy of each vaccine depends on how strong is the immunity granted overtime and whether the virus creates new variants. These vary between vaccines and people. It is important to follow the recommendations of your doctor, as they can advise you according to your health. For example, those immunocompromised might require multiple doses due to their weak immune system.

Eradication is the stop of a disease worldwide, while elimination is stopping the transmission in a specific area. Currently, smallpox is the only declared eradicated disease since May 1980. More information about this fact here.

When a vaccine is being created, researchers investigate how to obtain a stronger immunity. In some cases, only one dose is necessary (e.g. the Johnson & Johnson COVID-19 vaccine and smallpox vaccine) while in others, it is important to receive at least two (e.g. Pfizer and Moderna COVID-19 vaccines and the Measles, Mumps, and Rubella (MMR) vaccine). The number of doses has nothing to do with the efficacy of a vaccine.