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Questions and answers

What is an infectious disease?

Infectious diseases are caused by viruses and bacteria, the toxins thereof, protozoa and pathogenic fungi. Infectious diseases are transmitted from human to human through air and blood, by contact with hands and objects, sometimes through food, drink or soil, and through sexual contact. These can also be transmitted by ticks, mosquitoes, fleas, lice and even larger animals. Several factors can affect whether or not a person falls ill – the health conditions of the person, the manner and duration of exposure to the infectious agent, and the presence of immunity. A lot of infectious diseases can be provided protection from by way of vaccination.

 

How does the immune system protect against infectious diseases?

In order to combat an infectious disease, the immune system must first recognize the pathogens. The pathogens are detected by white blood cells, which then produce antibodies that correspond to the virus or bacteria. Antibodies have two tasks:

  • attacking pathogens with the objective of destroying them and combating the disease;
  • protecting people from this infectious disease. 

The production of antibodies does not begin as soon as a person becomes infected, instead, it usually takes 2–3 weeks. The next time you come across the same pathogens, the immune system is already ready to respond to them and shall react faster. In this case, the infectious disease does not occur or the course of disease is mild. Therefore, the person has become immune to the disease.

 

If I have recovered from a disease, will I have life-long immunity?

In the case of some infectious disease, having recovered from them provides the person with long-term or even life-long immunity. In this case, the person will no longer fall ill with this particular disease.

However, for many infectious diseases, immunity does not last for a long time. There are several reasons for this. Firstly, the pathogen may alter its structure to the point where the immune system can no longer recognize it. Secondly, the immune system may not develop a long-term “memory” when fighting with the pathogen, and as time goes by, the immunity will disappear.

 

How do vaccines protect from infectious diseases?

Vaccination is a natural way of developing immunity. The vaccine contains the particles of the virus or bacterium that causes the disease, through which the immune system recognizes the pathogen. However, the disease itself does not occur because of these particles. Therefore, as a result of vaccination, the immune system generates the same immunity as after having recovered from this infectious disease, but without danger or effort.

When a person who has been vaccinated against the disease becomes infected, the immune system is immediately ready to protect the body. The pathogens are destroyed before they can multiply. This also prevents the spread of infection to others. However, such a protective shield only works if a sufficient proportion of the population has been vaccinated. A decrease in the number of vaccinated people has led to recurrence of disease outbreaks in several European countries. A good example here is measles.

 

Why is vaccination necessary?

Avoiding a disease is always better and easier than experiencing the disease. Vaccination is a very effective and safe way of protecting children and adults from serious consequences.

Vaccination helps to prevent the spread of diseases and is especially needed for those who cannot be vaccinated for some reason.

The impact of vaccination on the spread of infectious diseases in Estonia can be seen in the infographics (link to the section “Historical effect of vaccines”). As you can see, effective work with vaccination has led to a situation in which many dangerous diseases have almost disappeared from Estonia over the years. Unfortunately, this has also led to a fake sense of security, as if it is no longer necessary to work on this. However, it remains true that infectious diseases are as dangerous as they were before, and if the opportunity arises, they will bring about a lot of unpleasant consequences.

 

Why is vaccination started already in infancy?

Because in the case of many illnesses, the course of illness is especially severe in infancy. For example, more than half of the severe cases of illness caused by type B haemophilia bacterium occur in children under the age of one year, and pertussis is also especially dangerous for the youngest ones. Infants and young children who have contracted hepatitis B are likely to develop chronic inflammation of the liver and liver cirrhosis. You can read more about the vaccination of children here (link to section “Vaccination of children”).

 

Why is it necessary to have several vaccinations against some diseases?

Repeated vaccinations are necessary to be sure that immunity is acquired and that is long-term. The number of vaccine injections needed to develop and maintain immunity and the frequency of vaccinations are determined by clinical studies.

 

Is immunity acquired right after vaccination?

After the first dose of the vaccine, it usually takes two to three weeks for immunity to develop. In some cases, the immune memory needs reminders in the form of re-vaccines. This way, the body is ready to deal with pathogens if necessary.

 

Why do vaccinated persons sometimes still get sick?

Vaccines, like other medicines, are not 100% effective. This means that a small number of vaccinated people do not produce enough antibodies and are still in danger. Contracting the disease can also be made possible by poor health, such as having diseases that include immunodeficiency.

It should also be taken into account that vaccines do not always provide lifelong protection.

 

What kind of vaccines are there?

There are several types of vaccines:

  • Live vaccines contain live attenuated microorganisms that are not capable of causing the disease, but provide the immune system with sufficient information to create antibodies. Live vaccines are, for example tuberculosis vaccine and the vaccines for measles, mumps and rubella.
  • Inactivated, i.e. killed vaccines contain non-living pathogens, which also provide the immune system with sufficient information to create the necessary antibodies. An inactivated vaccine is used, for example, to induce immunity against poliomyelitis.
  • In combination vaccines, a few precisely selected antigens are required to produce effective immunity. Combination vaccines are, for example, an acellular or cell-free pertussis vaccine, which contains three different antigens; a type B haemophilia infection vaccine, which contains two different antigens, and a hepatitis B vaccine, which contains one antigen. Both diphtheria and tetanus vaccines also contain one antigen.

 

What do vaccines contain?

In addition to the particles of pathogen(s), i.e. antigens, vaccines contain very small amounts of excipients that are necessary to increase the efficacy and safety of vaccines. These small amounts of substances do not have toxic effects. For the full list of excipients included in the vaccines, see the information leaflet of package of the medicinal product.

 

How effective are vaccines?

The effectiveness of vaccines is assessed on the basis of:

  • how many of the vaccinated persons developed antibodies necessary for immunity;
  • how many of the vaccinated persons did not contract the disease.

Vaccines are very effective – they have significantly reduced the incidence of certain infectious diseases (link to the section “Historical effect of vaccines”) and eradicated some completely. Most of the vaccines given to children cause immunity in 90–99% of patients. However, if the vaccinated child is still infected, they will suffer from this illness in a milder form.

 

Are vaccines safe?

You can read more about the safety of vaccines in the respective section (link to the “Safety” sub-section). 

 

Does vaccination cause illness?

Vaccines do not cause a person to become infected because they contain only inactivated or attenuated pathogens or particles that are not capable of causing an infectious disease.

It is also known that vaccines do not affect the incidence of other diseases. Occasionally, vaccination may randomly coincide with the onset of a health problem.

In Estonia, about 14,000 children are born every year. Therefore, the likelihood that some health problems will occur at the same time as vaccination is significant. Vaccines and their effects have been extensively and thoroughly studied, and so far there, no link has been established between vaccination and autism, diabetes, sudden infant death syndrome, asthma, atopic dermatitis, or other diseases and disorders.

 

Does vaccination weaken or impair the immune system?

Vaccination makes the immune system stronger and increase its readiness to protect the body when coming in contact with a particular pathogen. The immune system will continue working the same way as it did before.

 

Can vaccination overload the immune system?

Vaccination places an acceptable burden on the immune system. Modern combination vaccines contain significantly fewer ingredients than there are in microbes that cause diseases. For example, in a combination vaccine that protects against diphtheria, tetanus, pertussis, haemophilus infection and poliomyelitis, there are less than 25 ingredients and antigens, and in the pertussis producing bacterium, there are about 3,000 antigens.

The immune system of humans, including newborns and infants, is sufficiently strong to benefit from the administration of vaccines. A child is exposed to many microorganisms already during the labour and after it, and the child’s immune system protects them. Vaccine antigens are like a single drop in the sea of uncountable antigens.

 

Does vaccination during pregnancy affect the fetus?

Vaccination of pregnant women is necessary because infectious diseases also endanger pregnant women. This ensures that the unborn child is protected. Pregnant women are vaccinated only with inactivated, i.e. killed vaccines.

 

In which cases is vaccination not conducted?

There are very few contraindications to vaccination. If it is known that a person is hypersensitive to any of the vaccines or components of a vaccine, then this vaccine will not be administered to them. Live vaccines are contraindicated during pregnancy and in the case of a very severe immunodeficiency.

If a person is suffering from an illness with high fever, or one without a fever, but with a severe course of illness, the vaccination is postponed until the person has recovered from the illness. A mild illness (such as runny nose) is not a contraindication to vaccination.

 

Do vaccines have side effects, what kind?

Like other medicines, the use of vaccines may also bring about side effects. Generally, they are relatively mild.

Doctors are familiar with the side effects, their causes, the time of occurrence and are able to give guidelines on how to deal with the side effects. To learn more about potential side effects of a vaccine, be sure to read the product information leaflet of the medicine.

You can read more about side effects in general here (reference to the “Safety” sub-section) and information regarding recommended behaviour in case side effects occur is available here (reference to section “Behaviour in case of side effects”).

 

What to do if a health problem arises after vaccination?

Monitor your state of health or that of your child attentively during the day after the vaccination. If necessary, contact your family physician or call the family physician helpline 1220. If emergency medical assistance is needed, call 112.

Information regarding recommended behaviour in the case of side effects can be found here (reference to section “Behaviour in case of side effects”).

 

Which diseases can people get vaccinated against?

In Estonia, vaccinations against tuberculosis, viral hepatitis B, rotavirus infection, human papillomavirus (HPV), diphtheria, tetanus, pertussis, polio, Haemophilia type B, measles, mumps, and rubella, are conducted on the basis of the national immunisation schedule.

Effective vaccines are also available for protection against viral hepatitis A, influenza, pneumococcal disease, tick-borne encephalitis, cholera, chickenpox, herpes zoster, rabies and meningococcal infection.

When traveling to certain parts of the world, it is important and, in some cases, even compulsory to vaccinate against certain travel-related infectious diseases, such as Japanese encephalitis, typhoid fever or yellow fever.

You can read more about vaccine-preventable infectious diseases here (link to subsection “Diseases”).

 

Can different vaccines be administered at the same time?

As a rule, different vaccines may be administered concurrently. The human immune system is fully capable of dealing with them.

 

Why is it important to follow the vaccination schedule of the immunization programme?

The aim of vaccination is to prevent infectious diseases. Therefore, it must be done before contact with the pathogen. This is why vaccination injections are administered already to children.

In addition to the risk of illness, not following the immunisation schedule also means that the vaccination injections administered at a later time must be paid for (this is done by the state when vaccinations are conducted in a timely manner on the basis of the national immunisation schedule).

 

What to do if vaccination dates have not been adhered to?

If vaccinations are not completed or deadlines are not met, it is advisable to consult your family physician. It is always possible to continue vaccination.

 

Who to turn to for more detailed information on vaccination?

Further information on vaccination can be obtained from a family physician or family nurse.