Myth: "Side effects of vaccinations are concealed from the public."

Explanation: Making an informed decision on vaccination is both right and fitting. Such a decision includes weighing the benefits and risks, as any effective medicine can also cause side effects. Vaccine side effects are tracked and reported so that both doctors and patients are aware of safety signals. Some concern about serious vaccine side effects is understandable, especially if the impression has been given that they are not adequately communicated. In fact, vaccine-related communication tends to be more focussed on the benefits of vaccination than on the risks. This is mainly due to the fact that the Standing Committee on Vaccination (Ständige Impfkommission, STIKO) only recommends vaccinations whose benefits clearly outweigh the risks.

Serious side effects (beyond the usual level of a vaccine reaction) are very rarely observed in everyday medical practice. If side effects occur, they are reported and communicated in a transparent manner to medical professionals. Doctors who administer vaccines are obliged to report serious side effects. The Paul-Ehrlich-Institut evaluates the reports that are submitted and in turn informs medical professionals via methods such as direct healthcare professional communications. In addition, information on known vaccine side effects is included in each vaccine's summary of product characteristics, package leaflets, and information sheets. These communication strategies allow reported side effects to be taken into account in vaccination discussions, enabling patients to make an informed vaccination decision.

It’s a fact: All known vaccine side effects are communicated via a variety of channels.

Good to know: Vaccine side effects are categorised into vaccine reactions and vaccine complications. Vaccination reactions are the typical symptoms that occur after vaccination, such as redness, swelling at the vaccination site, fever, headache and body aches. These reactions usually subside after a few days without lasting damage and are signs of the immune system being activated, as is hoped for with a vaccine. Vaccination complications, on the other hand, are adverse drug reactions (ADRs) after vaccinations that go beyond the usual extent of a vaccination reaction. Vaccination complications must be reported.

An example of effective communication of serious vaccine side effects was the widely distributed communication to the public on the risk of thrombosis after the AstraZeneca vaccination against COVID-19. This information was shared by the Federal Ministry of Health (Bundesministerium für Gesundheit, BMG) and the Paul-Ehrlich-Institut. In the spring of 2021, very rare cases were reported of women aged ≤55 years who developed thrombosis after vaccination. The information was communicated to the public through a variety of channels. Vaccinations with this vaccine were simultaneously halted.

Myth: "Vaccinations cause allergies."

Explanation: In the past 30 years, many new vaccines have been developed, recommended and administered to protect against diseases that can have serious consequences. At the same time, more people are suffering from allergies than in the past. This leads to the logical assumption that the two developments could be linked. Since allergies can severely affect a patient's quality of life, it is understandable to be concerned. These concerns have led to many scientific studies investigating possible causes for the development of allergies. The methodologically sound studies in particular were unable to establish a link between vaccinations and allergies. There are even isolated indications that vaccines might offer temporary protection against new allergies.

Various explanations for the increased occurrence of allergies in recent decades are still being discussed. The most widespread theory is the "hygiene hypothesis". According to this hypothesis, our increased everyday awareness of hygiene and cleanliness leads to reduced contact with pathogens (mainly bacteria, fungi, viruses), parasites, and pollen. The immune system then reacts disproportionately to normally harmless irritants, thus resulting in more allergies.

It’s a fact: Vaccines generally do not promote the development of allergies. Although allergic reactions to vaccine ingredients can occur in individual cases, they can be ruled out as a cause of the increase in allergies in the general population.

Good to know: An allergy is a disproportionately strong immune system reaction to a normally harmless environmental substance. One example is a pollen allergy.

A vaccination, on the other hand, is a stimulation of the immune system to a cause a non-hazardous reaction to a normally dangerous pathogen in order to prepare the immune system for real contact with the pathogen.

In principle, people with allergies can and should also be vaccinated. The scientific evidence clearly shows that individuals with known allergies can be vaccinated safely in accordance with medical recommendations. Severe allergic reactions to vaccines are extremely rare and occur with a frequency of about one to ten cases per one million vaccinations.

When such reactions occur, they are usually caused by certain excipients or residues in the vaccine. One example is gelatin, which is found in many foods and some vaccines and has a known allergenic potential as an excipient.

Individuals with chicken protein allergies commonly seek out allergological advice before vaccinations, as traces of chicken protein may be present in some vaccines as a residue from the manufacturing process. The maximum permitted amount of chicken protein residue is clearly regulated in the European Pharmacopoeia.

All ingredients as well as known potential allergy risks are listed in the summary of product characteristics and package leaflet of authorised vaccines. In rare cases, this may mean that a particular vaccine is not suitable for individuals with allergies. The vaccinating doctor should therefore check for allergies relevant to the vaccination in discussion with the patient and check their allergy documentation if available.

Mahler V, Junker AC (2022): Anaphylaxis to additives in vaccines.
Allergo J Int 31: 123-136.
Text

Myth: "Autism can be triggered by vaccines."

Explanation: Autism diagnoses have increased in some parts of the world since the year 2000. At the same time, more vaccines were administered than in previous decades. This may lead to the conclusion that there could be a causal relationship between autism diagnoses and vaccinations. This conclusion, however, is incorrect. According to experts, the increasing number of diagnoses is due to increased awareness, better testing procedures, and more precise definitions of autism.

This myth first came on the scene in the 1990s, when a former doctor alleged with no scientific evidence that the combination vaccine (against measles, mumps, and rubella) could damage nerves and thus lead to autism. It later became known that his data (on twelve children) was falsified and that he had a personal financial interest in disseminating misinformation. His medical license was revoked due to unethical behaviour. His co-authors and the journal in which the "study" was published publicly distanced themselves from his statements and the paper was withdrawn.

Since then, many large-scale international studies have investigated whether such a connection could exist. The result: autism occurs just as frequently in vaccinated children as it does in unvaccinated children. There is no scientific evidence whatsoever to support the former doctor's claims.

It’s a fact: The results of numerous large studies indicate that vaccines can be ruled out as a possible cause of autism.

Good to know: The term "autism" is commonly used to group together several diagnoses that are referred to as autism spectrum disorders by the medical community. These are complex neurobiological conditions that are often associated with social interaction and communication disorders. The causes of autism have not yet been fully clarified. According to the information available to us today, there are very different factors that play a role in autism. The current focus is on genetic predisposition and changes in the biochemistry of the brain that increase the risk of developing autism. There is no single cause of autism.

In some cases, the adjuvants that are contained in some vaccines have been blamed for alleged harmful effects that can lead to autism. However, the vast majority of adjuvants used today have been known for decades and have proven their tolerability several times in studies. In addition, live vaccines such as the measles-mumps-rubella combination vaccine do not require an adjuvant because the immune system produces a sufficiently strong reaction to the weakened and harmless pathogens in the vaccine.

Myth: "Vaccines can cause cancer."

Explanation: Some vaccines protect against infections that can cause cancer. One benefit of HPV vaccination is that it can prevent the development of cervical cancer. Hepatitis B vaccination can prevent the development of liver cancer.

When the notion that vaccines contain carcinogenic substances is spread on social media or elsewhere, this can understandably lead to uncertainty. It would be disastrous if harmful, let alone carcinogenic substances got into a vaccine. There are multiple worldwide safety systems in place to prevent this. However, cancer in particular is a very emotional topic that is not always considered from a factual perspective. In many people's minds, a cancer diagnosis is associated with fears of serious health issues and questions of survival. Playing to these fears is a targeted strategy that is used again and again by anti-vaxxers. They use made-up terms such as “turbocancer” to create an association between vaccines and cancer.

However, this supposed association has absolutely no scientific basis. Vaccine components are very closely monitored by independent scientists around the world. It would quickly become apparent if any carcinogenic substances were to be found in vaccines. In addition, cancer cases are collated internationally in cancer registries. We would therefore notice if cancer cases were to accumulate after a particular vaccination. Multiple billions of vaccine doses have been administered, and there is still no scientific evidence that vaccines cause cancer.

It's a fact: Vaccines can protect against cancer. There are many causes of cancer. Some cancers are caused by viruses. In some cases, these serious consequences of infection can be prevented with vaccinations.

Good to know: In addition to the pathogen components, some vaccines also contain adjuvants. They help to stimulate the immune system and thus improve the effect of the vaccine. Adjuvants are also carefully tested worldwide for possible adverse effects and are not carcinogenic. The vast majority of adjuvants used today have been known for decades and have proven their tolerability several times in studies.

Also interesting to note: The mRNA technology used in some COVID-19 vaccines was originally developed for vaccinations against cancer. The idea is as simple as it is ingenious: a sample is taken to analyse the genetic fingerprint of the cancer cells. An individual vaccination is then produced for this one patient and their cancer. The vaccination should allow the immune system to target and combat the cancer cells. However, this is still only a theoretical concept and it will not be ready for the market until a few years from now.

Myth: "Vaccines cause infertility."

Explanation: The potential impact of vaccination on male and female fertility has been investigated in many studies using a variety of vaccines in multiple countries. The studies clearly showed that women get pregnant at the same rate regardless of whether they or their partners are vaccinated or unvaccinated. Vaccinations therefore have no effect on fertility.

It is understandable that individuals who wish to have children and pregnant women must be particularly careful regarding the use of vaccines and other medications. They do not want to harm their unborn child under any circumstances and hope to give their child the best possible start in life. However, this justified caution is sometimes selectively targeted to sow doubt about the safety of vaccines, especially on social media. One example used for such campaigns is the fact that in many Western countries there are more vaccinated individuals than ever before and that birth rates in those countries are falling at the same time. However, these two situations are not related. Falling birth rates are not the result of vaccinations but rather of changes in family planning practices in our modern society.

It’s a fact: Vaccines have no effect on fertility and are safe for those planning to have children and pregnant women. It is equally clear that some vaccines are particularly important before or during pregnancy to protect both child and mother, such as the pertussis vaccine (whooping cough).

Good to know: This myth is an example of one of the most common human fallacies, known in the scientific community as "correlation does not imply causation". This means that two observations that show similar trends (correlation) or are temporally linked (coincidence) are not necessarily caused one another (causation). Perhaps the best-known example of this is a study on the correlation between storks and the birth rate: the more storks that were living in a particular region, the more babies were born there. This observation is correct. Of course, this does not mean that the storks are delivering the children. This situation demonstrates correlation without causation.

It is also interesting to note that some vaccinations are expressly recommended during pregnancy, as they can protect the child after birth. This type of protection works via a transfer of the mother's antibodies, which were formed after vaccination, through the placenta to the child (around the 30th week of pregnancy). The transfer of antibodies via the placenta is important in cases such as pertussis vaccination (against whooping cough). Whooping cough is particularly dangerous for newborns in the first months of life, but it is not possible for them to be vaccinated at that time. Therefore, vaccination against whooping cough is recommended during every pregnancy. After birth, the child can receive additional antibodies from the mother via breast milk. Whether and how many antibodies are transferred from the mother to the child varies from pathogen to pathogen.

However, not all vaccines should be used indiscriminately during pregnancy. Vaccines that fall under the category of live vaccines, which contain attenuated but live pathogens, may not be used in pregnant women. This is because the immune system is repressed during pregnancy so that the growing child is not identified as a foreign body and attacked by the mother's immune cells. Dead vaccines, on the other hand, are usually not a problem for pregnant women.

A last note: during the COVID-19 pandemic, many people believed the myth that COVID-19 vaccines made people infertile. However, many international studies have demonstrated that COVID-19 vaccination does not make you infertile. On the contrary, the COVID-19 vaccination is expressly recommended for individuals who want to have children, as a SARS-CoV-2 infection can be dangerous for both mother and child.

Myth: "Vaccines cause the diseases they are intended to protect against."

Explanation: Most of the vaccines available contain dead pathogens or their components. These vaccines are known as dead or inactivated vaccines. Dead vaccines cannot cause the disease they are intended to protect. There is also a type of vaccine known as a live vaccine that contains attenuated (weakened) pathogens. Only a few vaccines available in Germany belong to this type of vaccine. Live vaccines also cannot cause the disease against which they are intended to protect. However, in rare cases they can produce illnesses which mimic the clinical symptoms of the disease in individuals with weakened immune systems. Therefore, live vaccines with attenuated pathogens are used in immunocompromised persons only after very careful consideration of the contraindications.

Some people believe that vaccines can cause the disease against which they are intended to protect. This is not the case. However, the possible complications of a vaccine can sometimes be mistaken for the disease itself. For example, fever and body aches can occasionally develop after an influenza vaccination. This gives the appearance that the vaccination has triggered the flu. However, these symptoms in fact are a sign that the immune system is responding to the vaccine. The symptoms usually resolve after a few days.

It's a fact: Vaccines cannot cause the disease against which they are intended to protect. Only in very rare, isolated cases can the use of live vaccines in individuals with weakened immune systems lead to an illness with the same symptoms, which is why these vaccines are not recommended for such risk groups.

Good to know: Regardless of the vaccine type, vaccinations may result in fever, nausea, drowsiness, and swelling and redness at the injection site. These symptoms are signs of the desired healthy immune system reactions to the administered vaccine.

However, the possible side effects of the vaccine should not be confused with the disease against which it is intended to protect. An example of this confusion is the condition known as "vaccine measles". The measles vaccine contains a weakened version that is still capable of reproduction. This means that around five percent of those vaccinated develop a measles-like rash and a fever after about 7-10 days. These symptoms usually resolve after a few days and are associated with the development of a strong immunity to measles. A fully developed case of the measles or complications such as an ear infection or pneumonia does not occur.

A historical example from decades ago of a vaccine that could actually cause a disease is the polio vaccine. The oral vaccine against polio that was introduced in the early 1960s was a live vaccine. In rare cases, polio vaccination resulted in illnesses caused by the vaccine virus. For this reason, since 1998 the Standing Committee on Vaccination (STIKO) has recommended polio vaccination with only the dead vaccine, which cannot cause the disease. The polio vaccine is thus also a good example of how vaccines - like other medicinal products - are constantly being improved to optimise safety and protection.

Myth: "The side effects and risks of vaccinations are completely unpredictable."

Explanation: In today's world, every vaccine must prove its safety and tolerability in clinical trials before it is authorised. After authorisation, doctors (in accordance with professional codes of conduct and the Infection Protection Act) are additionally obliged to report suspected vaccine complications to the Paul-Ehrlich-Institut. Patients can also report their suspected vaccine complications to the Paul-Ehrlich-Institut at any time. The Paul-Ehrlich-Institut assesses whether the reported complication can be traced back to the vaccination, i.e. whether the vaccination could be the real reason for the reported symptoms.

This reporting system sometimes detects new safety signals for very rare side effects, which is sometimes cited on social media as "proof" that the side effects and risks of vaccinations are unpredictable. It is, however, a false conclusion to believe that this is evidence of deficient safety monitoring. On the contrary, the mere fact that the reports of suspected side effects and complications are so closely studied and even very rare adverse events can be detected shows how seriously vaccine safety is taken. In the event that safety signals are identified, it is then possible to respond quickly and introduce appropriate countermeasures (e.g. changes to the STIKO recommendations).

It’s a fact: Risks and side effects of vaccines are identified in clinical trials prior to authorisation and are continuously monitored worldwide after authorisation. Severe side effects after vaccination are rare, but they do occur. It is important that everyone is informed about the possible risks of vaccines.

Good to know – examples of side effects or suspected side effects that were detected and investigated thanks to the reporting system: A few years ago, cases of sudden infant death syndrome were reported that occurred shortly after immunisation. These reports were taken very seriously and thoroughly investigated. In the meantime, the assumption that vaccines cause sudden infant death syndrome was already circulating. This is not the case. Studies that have been completed since that time point in the opposite direction: doctors at the University of Magdeburg found in an extensive analysis of over 300 child deaths that the infants had been vaccinated less frequently and later than usual.

At the beginning of the vaccination campaign, the COVID-19 vaccine Vaxzevria from the manufacturer AstraZeneca was found in very rare cases to cause cerebral vein thrombosis (known as sinus vein thrombosis) in younger vaccinated individuals. This serious adverse effect of vaccination could not be identified in the clinical trials, as it occurs too rarely to be detected in marketing authorisation trials with a limited number of participants. The reporting system in Germany and other countries made it possible to identify the cases and assess them as a safety signal for vaccination. The Standing Committee on Vaccination (STIKO) at the Robert Koch-Institut (RKI) reacted and restricted its vaccination recommendation for this vaccine.

Myth: "Infants and toddlers are being vaccinated too early."

Explanation: Many vaccinations are recommended for infants and toddlers at an early age. The first should be administered just a few weeks after birth. This is a reasonable timeframe, as the recommended age for vaccination is based on the risk level of the child to be protected. Certain infections can have a markedly more severe course of disease in babies and toddlers than in older children. This is due to the narrowness of infants' airways and their still-developing immune systems that cannot effectively fight certain infections, among other factors. Administering vaccines at the recommended time protects infants and young children from infections and potentially serious consequences.

Many parents are particularly cautious when it comes to medications and vaccinations for their children. That is understandable. Young children's bodies, and those of infants in particular, are in the early stages of development. As a result, some parents have concerns about having their children vaccinated so young. However, early vaccinations are very important precisely because toddlers and infants are particularly vulnerable. For example, the pneumococcal vaccine, recommended after a child reaches two months of age, reliably protects against invasive pneumococcal disease. This disease is a particularly serious consequence of infection and can lead to other conditions, such as meningitis. Children, especially those in their first two years of life, are at an increased risk of invasive pneumococcal disease.

It's a fact: Vaccinations are important for the health of children and toddlers. Vaccinations protect infants and toddlers at a particularly vulnerable age. The recommended vaccines must be administered as early as possible to obtain this protection.

Good to know: Some parents fear that infants will tolerate vaccinations poorly. This is one reason why they may prefer their child receive vaccinations later. However, the routine vaccination of infants carried out for decades shows that vaccinations are also tolerable in infancy. Vaccination reactions occur – in older age groups as well – and are resolved after a few days. Serious side effects are very rare. Vaccinations in infancy are therefore safe and should not be postponed.

Even premature babies should be vaccinated early in order to provide optimal protection. Premature babies are particularly more susceptible to infections and have an increased risk of severe complications.

As one final example to illustrate why infants and toddlers in particular benefit from early vaccinations: vaccination against pertussis (whooping cough). Children who contract whooping cough when they are younger than six months are more likely to experience complications such as respiratory failure, blood count changes, or pneumonia and they are more likely to require hospitalisation. As children get older, their complication rate decreases. Therefore, young infants in particular benefit from timely pertussis vaccination. In order to protect young infants before they can build up their own defences through vaccination, it is important that their mothers are vaccinated against pertussis during pregnancy and thus pass on protective antibodies to the infants.

Myth: "Vaccines are more dangerous than infections."

Explanation: Vaccines are only authorised and recommended if their potential benefit (protection from infection and serious illness) is greater than their potential risk (possible side effects). The risks associated with some diseases can be quite dramatic, such as meningitis (from measles) or paralysis (from polio). These risks can be significantly reduced or even eliminated by vaccination.

Successful vaccination programmes have significantly curtailed or even completely eradicated many diseases, such as rubella in Germany. As a result, most people no longer have any contact with vaccine-preventable diseases. Therefore, it is understandable to get the impression that the possible risks of vaccination are more serious than those of the diseases with which one has no direct experience. However, as a matter of fact vaccinations have successfully prevented many, often severe, illnesses which would reappear if vaccination rates fell.

It's a fact: Infections and their possible complications are significantly riskier than the recommended vaccinations. Vaccines are only authorised and recommended if their benefits are significantly greater than their potential risks.

Good to know – comparison of the risks of infection and vaccination, using measles as an example: Out of every 1,000 measles patients, up to 140 suffer from ear infections, up to 120 from diarrhoea and up to 100 from pneumonia. Inflammation of the brain, known as measles encephalitis, develops in about one in every 1,000 to 2,000 children who develop measles. Measles encephalitis can lead to permanent brain damage or even death. In addition, the measles virus has been shown to weaken the immune system of those affected. This leads to the destruction of the established immune protection against certain pathogens and additional infections (such as in the upper respiratory tract) can still occur months later.

For comparison: after the combination vaccine against measles, mumps, and rubella (MMR), typical vaccination reactions occur in 100 out of every 1,000 vaccinated people. These reactions usually involve redness and swelling at the injection site, headache, and fever for one to two days. Additionally, a rash (known as "vaccine measles") can occur in about 50 out of every 1,000 vaccinated people. The rash lasts for about one to three days and is not contagious. More severe adverse effects of vaccination are rare: an acute allergic reaction occurs in one to four cases of every million people vaccinated. In about 30 out of every million vaccinated people, immune thrombocytopenia (a drop in platelet levels) can occur, which usually goes away on its own.

The comparison makes it clear: the measles vaccination is much safer than an infection with measles viruses.

Myth: "Vaccinations are pointless because they do not provide 100 per cent protection."

Explanation: No vaccine can claim to protect all recipients without exception, just as no medication works equally for all patients. Despite this, vaccines are effective. They reduce the likelihood of becoming infected, developing the disease, and passing on pathogens to others. They can also markedly reduce the severity of an illness.

It is naturally desirable for medical treatments to be effective in all patients and under all circumstances. However, no vaccine currently available can guarantee 100 per cent protection. It is understandable that this may be unsatisfactory. However, many other treatments are not 100 per cent effective: taking ibuprofen, for example, does not help 100 per cent against headaches. Nevertheless, many people trust in the beneficial effects of ibuprofen because in many cases the medicine was able to relieve their headache. Much the same applies to vaccines. Even if vaccines are not 100 per cent effective, this does not mean that vaccines are fundamentally incapable of providing protection. Even 90 per cent efficacy against a disease reduces the risk of catching the disease substantially and protects a large majority of vaccinated individuals.

It's a fact: It is sensible to get vaccinated, even if the protection cannot be 100%.

Good to know: Different vaccines protect against infection or disease for different lengths of time. For example, the influenza vaccination should be refreshed annually, as the vaccine is adjusted every year to match the influenza viruses expected to be in circulation. This adjustment is carried out because influenza viruses are constantly changing and different variants circulate. It is possible that virus variants other than those predicted will be prevalent and the vaccine's protection level will be lower than expected. The progress and complications of the disease are nevertheless mitigated by the vaccination (also by any existing residual immunity).

Another impressive example is the measles vaccination. If the measles virus enters the body of a vaccinated person, it is very quickly rendered harmless before it can multiply and cause a measles infection. As a result, vaccination provides protection from a rapid spreading of the disease to others. Even if protection cannot be 100%, the measles vaccination is particularly reliable.

One last note: the number of people who become infected despite being vaccinated depends on factors such as the rate at which the pathogen is circulating in the population. The more cases there are amongst the population, the higher the chance that vaccinated people can also become infected. The COVID-19 pandemic provided an example of this phenomenon.