Immunization is safe and one of the most effective disease prevention measures

Seven most often used controversial arguments are discussed: Controversial argument 1

Most vaccines are not really indicated, because many of the so-called vaccine-preventable diseases already disappeared due to the improved socioeconomic conditions before vaccines were introduced.

Counter-argument

Improved socioeconomic conditions as well as the development of antibiotics have undoubtedly had a great impact on disease incidence, disease-related complications and death. However, the immediate and direct impact of vaccines is absolutely significant. A few examples may underline the effectiveness of selected immunization programs, many more examples could be given.

- The implementation of oral poliovirus vaccine (OPV) mass immunization in Germany eliminated poliomyelitis within a few months (East Germany)/few years (West Germany) (Fig. 1) [1].

- Due to decreasing OPV coverage in Albania, a large re-appearance of poliomyelitis occurred in 1996. OPV mass immunization stopped the outbreak within few weeks (Fig. 2) [2].

_ In November 1999, a newly developed conjugated meningococcal group C vaccine was recommended for all children and adolescents in England and Wales. By 2003, cases and deaths due to meningococcal group C disease were reduced by more than 90% (Fig. 3) [3].

- The success of immunization programs implemented in the US Pink Book, 8th edition 2004: Appendices) is another convincing example (Fig. 4) [4].

10000

1000

1000

' V" v.

•West G T'r t r i

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i t

\ H \ * •>--.' ^

\ 63-S9: only 22 cases of '■* , vaccine-associated paralytic V ' * i Y poliomyelitis (VAPP) 1,1 1 •

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Meeting DW (German Viral Disease Assoc, Berlin 2002)

Figure 1. Implementation of polio immunization (OPV) in Germany. Start of massive campaigns in East (1960) and West (1962).

Figure 2. Polio outbreak in Albania - Outbreak control with OPV, April-December 1996.

1996

Figure 2. Polio outbreak in Albania - Outbreak control with OPV, April-December 1996.

Controversial argument 2

In a country where a disease no longer exists, there is no longer an indication to continue with immunization against this disease.

cases

1400 fl-

1998 1999 2000 2001 2002 2003

Source: Campbell H, Ramsay M, Gungabissoon U, Miller f. Impact of MenC conjugate vaccination programme in England- HPA Surveillance Report 03

Figure 3. Success of immunization program with conjugated meningococcal serogroup C vaccine, England 1999-2003.

Figure 4. Impact of immunization programs, USA 1945-2002.

Counter-argument

It is true that following the implementation of nationwide immunization programs in industrially developed countries in the second half of the last century, morbidity and mortality of childhood diseases, such as diphtheria, poliomyelitis, measles, and pertussis in children, decreased to very low levels or even levels close to elimination. These diseases are much less common now, but the bacteria and viruses that cause them are still present. Travelers can carry diseases from country to country, and if an individual is not immunized he/she could be at serious risk. It is also important to realize that some people cannot have vaccines because of certain medical conditions or severe allergies. These people are susceptible to disease, and their only hope of protection is that people around them are immune and cannot pass disease along to them. A successful immunization program depends on the cooperation of every individual to ensure the good of all. Many examples can be provided where unjustified counter-propaganda, religious barriers, or program management failures negatively influenced the acceptance of immunization and caused the re-emergence of vaccine-preventable diseases.

- Pertussis: In the 1970s in Japan, a near boycott of the vaccine due to suspected vaccine complications caused the recurrence of epidemic pertussis with hundreds of deaths. Similarly, because of aggressive publicity concerning central nervous system damage following immunization using whole-cell pertussis vaccine in UK, coverage rates fell from 75% to about 25% during the mid-1970s, and major epidemics re-emerged. The re-implementation of pertussis immunization programs (whole-cell vaccine in UK and acellular vaccine in Japan) brought pertussis back under control.

- Poliomyelitis: Two outbreaks of poliomyelitis occurred in particular religious communities of 200 000 individuals dispersed throughout the Netherlands who refused immunization. One outbreak caused 110 cases in 1978, and the second outbreak caused 71 cases in 1992. There was only a single case of poliomyelitis among other Dutch people as the Dutch population in general is well protected through inactivated poliovirus vaccine (IPV) immunization programs achieving high coverage rates. However, contact cases from the 1978 outbreak occurred in religious groups in North America.

- Diphtheria: In 1958-1959, a near-universal childhood diphtheria immunization program began throughout the Soviet Union, and by 1963, the incidence of diphtheria had decreased by > 90%. Epidemic diphtheria re-emerged in the Russian Federation in 1990, spread to all Newly Independent States (NIS) of the former USSR by the end of 1994, and developed into the largest diphtheria epidemic in the world since the implementation of diphtheria immunization programs. In 1995 and 1996, more than 90% of all diphtheria cases and deaths reported worldwide occurred in the NIS. As a result of the political and socioeconomic changes in the former USSR, various factors contributed to the epidemic, including decreasing immunization coverage in children, immunity gaps in adults, altered public perception of the benefits and risks of immunization, population movement, deteriorating health infrastructure, initial shortages of

Table 1. Comparison of severity of diseases and complications following immunization

Disease

Severity of disease

Complications following immunization

Diphtheria Hepatitis B

H. influenzae disease

Influenza

Measles

Meningococcal disease, invasive

Mumps

Pertussis

Pneumococcal disease in children, invasive

Case fatality rate (CFR) 1-7%, nerve paralysis and myocarditis often occur

1% (Western Europe. North America) to 10% (Asia, Pacific, sub-Saharan Africa) of population are chronically infected; about 1 in 4 chronic carriers develop cirrhosis or liver cancer

CFR: meningitis, 5%; epiglottiditis, 1%; about 1 in 4 survivors has permanent brain or nerve damage

Causes increased hospitalization rates and excess mortality in high risk groups, particularly the elderly and the chronically ill

4% of patients develop pneumonia, and 1 in 1000 encephalitis; CFR of measles encephalitis, 10%; and 40% have permanent brain damage; rarely subacute sclerosing panencephalitis (SSPE) occurs

Meningitis, septicemia; CFR ~10%; ~10-20% permanent damage (CNS, physical sequelae range from necrosis to amputation following extensive gangrene, bone lesions and skeletal growth disturbances

4% of patients develop meningitis, occasionally mumps causes deafness; 1 in 5 males past puberty develop inflammation of testes

CFR (due to pneumonia or encephalopathy) in infants about 1%

Meningitis, septicemia, bacteremia; CFR ~5%; ~ 20% permanent damage (CNS, hearing loss, learning disabilities)

Rarely, allergic reactions, anaphylax-is and peripheral neuritis following DTP may occur

In rare cases, allergic reactions or anaphylaxis may occur

In case of fever young children may develop febrile seizures, allergic reactions are very rare

In rare cases allergic reactions, vas-culitis or thrombocytopenia may occur; Guillain-Barre syndrome is reported in about 1 in 1 million vaccinees

In rare cases, allergic reactions or anaphylaxis may occur; in case of fever young children may develop febrile seizures

Following conjugated MenC vaccine only local and systemic reactions reported

Allergic reactions are rare; in case of fever young children may develop febrile seizures; meningitis may occur but has not reported following mumps vaccines based on the 'Jeryl Lynn' and 'Jeryl Lynn'-derived strains

In rare cases, allergic reactions, ana-phylaxis, hypotonic-hyporesponsive following DTP may occur; following whole-cell pertussis vaccine, rare cases of encephalopathy occurred

Following conjugated pneumococcal vaccine only local and systemic reactions reported, allergic reactions are very rare

Table 1 (continued)

Disease

Severity of disease

Complications following immunization

Poliomyelitis

Rubella

Tetanus

CFR 5%; 1 in 2 survivors is permanently paralyzed

50% of adolescents and adults develop arthritis/arthralgia; very rarely thrombocytopenia or encephalitis; 9 of 10 babies infected during the first 10 weeks of pregnancy will develop major congenital abnormalities (CRS)

CFR: 10%, much higher in older individuals

Vaccine-associated paralytic poliomyelitis may occur following OPV; IPV has an excellent safety profile

In case of fever young children may develop febrile seizures, allergic reactions are very rare; arthritis/ arthralgia may rarely occur in (preferably female) adolescents/adults

In rare cases allergic reactions, anaphylaxis and peripheral neuritis may occur vaccine, and delays in implementing control measures. Since 1995, aggressive control measures, including mass immunizations as the core element of the strategy, were implemented in close collaboration between the NIS and international donors and stopped the epidemics [2].

Controversial argument 3

Natural immunity is better than vaccine-induced immunity.

Counter-argument

While vaccine-induced immunity may diminish with time, 'natural' immunity, acquired through natural disease persists usually longer and often lifelong. However, for most vaccines, individuals can receive booster immunization(s) if the vaccine-induced immunity falls to a low level. Therefore, vaccine-induced immunity can also protect lifelong. The problem is that 'natural' diseases have a high risk of serious illness and occasionally death. Natural disease is far more risky than immunization (see Tab. 1).

Controversial argument 4

Many vaccines are not indicated because they are often useless and many people get the disease despite being immunized.

Counter-argument

First, no vaccine is 100% effective. For reasons related to the individual, not all immunized individuals develop immunity. Most vaccines are effective for 85-95% of recipients. Second, in countries with high immunization coverage, the people who have been immunized vastly outnumber those who have not. How these two factors work together to result in outbreaks although the majority of cases have been immunized can be easily understood by looking at the following example: In a dormitory of 300 students, the entire student body is exposed to measles, none has ever had measles. Of these, 295 have had two doses of measles vaccine, the efficacy rate for two doses of measles is at least 95%; and the 5 non-immunized students will get measles, of course. However, of the 295 students, who have been immunized, we would expect approximately 5% (15 students) not to respond to the vaccine and they, too, become infected. Therefore, 15 of 20, or about 70%, of the cases occur in students who have been fully immunized. Under circumstances of high coverage those individuals who were immunized and did not respond outnumbered those who had not been immunized. This does not prove the vaccine did not work: 100% of the students who had not been immunized got measles, compared with approximately 5% of those who had been immunized [5]. We should also note that illness in immunized individuals is usually much less severe than in those who were not immunized.

Controversial argument 5

Multiple immunizations or combination vaccines overload the immune system.

Counter-argument

The increase in the number of vaccines given to children, and preferably administered as combination vaccines, has led to concerns about the possible adverse effects of the aggregate vaccine exposure, especially on the developing immune system. However, in day-to-day life, all children and adults confront enormous numbers of substances that provoke a reaction from the immune system, and the immune system responds to each of these in various ways to protect the body. Studies of the diversity of antigen receptors indicate that the immune system can respond to an extremely large number of antigens. Scientists estimate that the immune system can recognize and respond to hundreds of thousands, if not millions, of different organisms. In the face of these normal events, it seems unlikely that the number of separate antigens contained in childhood vaccines would represent an appreciable added burden on the immune system that would be

Table 2. Content of immunogenic proteins and polysaccharides in vaccines -

1900 vs 2000

1900

1960s

2000

Vaccine Proteins

Vaccine Proteins

Vaccine

Proteins/ polysaccharides

Smallpox ~200

Smallpox

~200

Measles-mumps-rubella

24

Diphtheria-tetanus

2

Diphtheria-tetanus

2

Pertussis (whole-cell)

Poliomyelitis H. influenzae type b Hepatitis B

15 2 1

Total ~200

Total

~3200

Total Western European countries

46-49

Varicella

69

Plus additional vaccines included in the US vaccination schedule

Pneumo coccal conjugate vaccine

8

Total US

123-126

immunosuppressive. We should also consider that the number of antigens received by children during routine childhood immunization has actually decreased compared with immunization programs used during the 20th century, in particular the 1960s. The replacement of whole-cell pertussis vaccine by acellular pertussis vaccine (introduced in most European and North American countries as well as in Australia, Japan and many other regions) decreased the content of immunogenic proteins and polysaccharides from approximately 3000 to 50-125 (Tab. 2, adapted from [6]).

The authors of carefully designed studies concluded that there is no evidence that adding vaccines to combination products increases the burden on the immune system. Young infants have a great capacity to respond to multiple vaccines. Increased reactogenicity following the receipt of combination vaccines has also not been a major issue. Combining antigens usually does not increase adverse effects, but it can lead to an overall reduction in adverse events. Neither the licensing agencies nor the national advisory boards on immunization would recommend the simultaneous administration of any vaccines or the use of combination vaccines until studies have confirmed the safety and efficacy. What is the practical justification for the use of a combination vaccine or several vaccines during the same visit? First, we want to immunize children as early as possible to give them protection during the vulnerable early months of their lives. Second, it means fewer office visits, which saves parents both time and money and may be less traumatic for the child [5-8].

Controversial argument 6

Vaccines are not indicated because they are not safe and cause much more complications than natural disease.

Counter-argument

Vaccines are among the safest tools of modern medicine. Following immunization, local and/or systemic reactions may develop such as redness, swelling or tenderness at the injection site, or a mild fever, but these reactions are most often minor and temporary. Serious side effects can happen, but are extremely rare. On the other hand, the dangers of vaccine-preventable diseases are many times greater than the risk of a serious adverse reaction to the vaccine. Examples for both the severity of diseases and complications following immunization have been provided in Table 1. All vaccines are manufactured according to strict manufacturing guidelines. Before vaccines are licensed they are tested for safety and efficacy in carefully designed clinical trials. All vaccine manufacturing facilities and vaccine products are licensed by the national or supranational licensing authorities such as the European Medicines Evaluation Agency (EMEA) or the (US) Food and Drug Administration (FDA). In addition, every vaccine lot is safety-tested by the manufacturer. The results of these tests are reviewed by the licensing authority, which may repeat some of these tests as an additional protective measure. The licensing authorities also inspect vaccine-manufacturing facilities regularly to ensure adherence to manufacturing procedures and product-testing regulations, and review in most countries the adverse event reports searching for unusual patterns of licensed vaccines [5, 7, 8].

Controversial argument 7

Instead of preventing diseases vaccines cause diseases. Counter-argument

Vaccines have been spuriously linked by various researchers to asthma, autism, Crohn's disease, diabetes, multiple sclerosis (MS), permanent brain damage, and sudden infant death syndrome (SIDS). Is there any evidence for the causal relationship between immunization and the diseases mentioned?

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