6.3.5. Vaccine-preventable diseases (VPD)

 

Several of the serious vaccine-preventable diseases are now almost eradicated from the EU. There have been no endemic cases of polio since 1992, only a few cases of diphtheria are still being reported annually from a couple of Member States, and reported tetanus rates are around one per million or lower.

 

All diseases covered by the MMR vaccine (measles, mumps and rubella), continue to show a good decline in the EU (apart from mumps in recent years), even though vaccine coverage is not uniform, with Germany reporting almost three quarters of all EU measles cases. The same downward trend is seen for invasive infection with Haemophilus influenzae type b in the countries that have introduced this vaccine. For pertussis, the picture is somewhat more complex: overall EU incidence seems to be rising slightly, and there are indications that the programmes have not achieved the intended effect of preventing death in young infants, which is one of the main objectives of a pertussis programme.

 

There are two invasive bacterial infections for which vaccines are available for some of their strains but that are still not routinely used in most Member States. These are invasive pneumococcal and meningococcal infections. Rates for invasive pneumococcal infection seem to remain stable across the EU at between five and six cases per 100 000 per year, but this is a serious infectious disease causing several thousand deaths each year, especially in the very young and the very old. Meningococcal meningitis is one of the diseases for which surveillance figures are most reliable: it is a serious and very characteristic disease receiving high public attention. Annual rates remain relatively stable at between one and two cases per 100 000 per year. Good vaccines are only available for one of the two types commonly seen in Europe, but are being introduced in some Member States.

 

Important challenges in the coming years are to meet the goal of eliminating measles and congenital rubella and maintaining the polio-free situation. Most of the childhood diseases that are now preventable by vaccination have been decreasing over the past few years as a result of effective childhood vaccination programmes. Yet, despite all the efforts, outbreaks still occur in population subgroups where vaccination uptake remains poor.

 

New vaccines have recently been, or soon will be, licensed (against varicella (chickenpox), human papilloma virus (HPV), and rotavirus). This raises the question as to whether these vaccines should be included in vaccination programmes, and if yes, how to monitor their impact and adverse effects.

 

Although Europe has maintained high vaccination coverage and even increased it, there have been areas of decline in the uptake of certain vaccines, with important consequences for the re-emergence and outbreaks of certain diseases. Examples are diphtheria during the 1990s in the Russian Federation and the former Soviet Republics and Baltic States (particularly in Latvia). Also some Western European countries have had to cope with a decrease from previously attained vaccine coverage levels. Political and socioeconomic changes that followed the collapse of the former USSR, and population density and deprivation in specific inner urban areas, were both strongly correlated with lower vaccination uptake.

High vaccination coverage does not exhibit a direct relationship with the wealth of a country, but with proper public health policies. For example, there is a cluster of countries under the GNP threshold, but with over 95% measles vaccine coverage; most of these are in the new EU Member States (figure 6.5).

 

Figure 6.5. Measles (MCV1) vaccine coverage.

 

6.3.5.1. Bacterial infections

 

Infection due to Streptococcus pneumoniae (pneumococcus) mainly affects the youngest and the oldest, and is the main cause of bacterial respiratory tract infections in all age groups, but is also common as asymptomatic carriage in the nasopharynx of young children. Invasive infections carry a high death rate, and are a major cause of infection-related death in young children. Unlike the older ‘polysaccharide’ vaccines, a new generation of ‘conjugated’ vaccines provide good protection against invasive disease even in very young children. As these vaccines also protect against the carriage of the bacteria, they have a potentially important role in preventing the spread of antibiotic-resistant pneumococci in the child population.

 

The trends of invasive pneumococcal infections over the last 10 years were stable in most countries, with the exception of Denmark (declining) and the UK (increasing). In 2005, a total of 19 665 invasive pneumococcal infections (5.83 per 100 000 per year) were reported by 19 countries. Sweden (15.76 per 100 000) followed by Belgium (15.45 per 100 000) reported the highest incidence rates. Incidence rates were the highest in the over-65 age group (15.3 per 100 000), followed by the under-4 age group (14.1 per 100 000), while the incidence rate in the five to 24 year-olds remained low. After 25 years of age, the incidence rates increased with age.

 

 

Conjugated pneumococcal vaccine was registered in the EU in early 2001, and 12 European countries have now introduced it as a universal vaccine in their childhood vaccination schemes, while several others recommend it for children at-risk. As the vaccine does not cover all serotypes of pneumococci, there is a need for enhanced surveillance both of the occurrence of the disease and the distribution of serotypes.

 

Invasive meningococcal disease

 

Invasive meningococcal disease, caused by the bacterium Neisseria meningitides (meningococcus), is most common in young children, with a secondary peak among teenagers. The death rate from invasive disease remains high (around 8%) and survivors may suffer from serious complications, including deafness, neurological problems and even amputations. Most disease in Europe is caused by serogroups B and C. Since 1999, several countries have introduced vaccination programmes against serogroup C disease, using a new conjugated vaccine, but to date there is no vaccine against serogroup B disease.

 

Since 1999, countries such as Iceland and Ireland, that experienced high incidence, show a sustained decrease possibly due to the introduction of the meningococcal C vaccine in high-risk populations. In the other countries, the reported incidence varied below 2/100 000 per year with stable trends or even with a slight decrease in the past few years after the introduction of the vaccine. In 2005, a total of 5 494 cases were reported by 26 countries. Ireland (with 4.94 per 100 000) and Malta (2.73 per 100 000) reported the highest incidence rates.

 

Invasive infection caused by Haemophilus influenzae type b

 

Haemophilus influenzae type b (Hib) is a respiratory tract bacterium, capable of causing meningitis and other severe systemic infections in young children. Effective vaccines are available against invasive Hib infection, and there has been a clearly declining trend in Europe over the last 10 years (most markedly in 1996–2001). Most countries had a stable incidence rate over the past five years, but a slow increase was observed in the Netherlands, Ireland and the UK. In 2005, 1 145 cases were reported by 25 countries. Estonia reported the highest incidence rate, with 1.48 per 100 000, followed by Sweden (1.31 per 100 000). Hib vaccination is now included in all immunisation schedules in the EU countries except in Poland, Romania and Bulgaria.

 

Pertussis

 

Pertussis is an acute bacterial infection of the respiratory tract caused by the bacterium Bordetella pertussis. There is an effective vaccine for this disease.

In the last 10 years, an overall higher incidence has been observed in the Northern countries: Estonia, Finland, the Netherlands, Norway and Sweden. A dramatic decrease was observed in Sweden at the beginning of this period and in the UK and Ireland over the whole period. For the other countries, the general incidence was lower. A slight decrease was observed between 1995 and 2000, but after 2002, some countries have been showing increasing trends. A very high proportion of cases have been reported among the youngest age groups (0–14 years).

 

In 2005, a total of 13 207 cases were reported by 24 countries. The highest rate by far was reported in the Netherlands (40.17 per 100 000), with Norway reporting a rate of 19.10 per 100 000. By contrast, the overall incidence rate in the EU was 4.10 per 100 000 per year. Thus pertussis, although known to be preventable by vaccine, still affects several European countries, and in some cases quite dramatically. Close monitoring in all EU countries is needed to better assess the real burden and risk of transmission of pertussis in order to refine control measures.

 

Diphtheria

 

Diphtheria is an acute disease with inflammation of the mucosal surfaces of the upper respiratory tract caused by a toxin from the bacterium Corynebacterium diphtheriae. Diphtheria is transmitted from person to person through small droplets, and the disease is preventable by vaccination. Since 1995, the Baltic countries, in particular Latvia, have been most affected. The incidence in Latvia peaked in 1995 (15 per 100 000 per year) with a second peak in 2000 (11 per 100 000 per year). In Estonia and Lithuania the incidences in 1995 were about one tenth of that of Latvia, and have gradually decreased over the period. In the other EU countries, cases are only observed sporadically. In 2005, only Latvia reported cases (20) with an incidence of 0.87 per 100 000.

 

Tetanus

 

Tetanus is induced by an exotoxin of the bacterium Clostridium tetani. The disease is characterised by painful muscular contractions primarily of the facial muscles. Generalised spasms can occur. The case fatality rate ranges from 10% to over 80% with the highest risk in infants and the elderly. Tetanus is mostly seen after contaminated injuries, and the infection is not transmissible between humans. There is an effective vaccine available.

 

An overall decreasing trend has been seen over the last 10 years, with a slight increase between 2001 and 2003. The incidence rates were always below 0.2 per 100 000 per year in the EU15 states, except for Italy and Portugal in 1995. In the new Member States, tetanus incidence rates were below 0.35 per 100 000 per year, except for Slovenia where incidence was at 0.45 per 100 000 per year in 2000 (nine cases) and for Malta with 0.5 per 100 000 per year in 2002 (two cases). In 2005, altogether 137 cases were reported by 21 countries. Italy reported almost 50% of all cases and the highest incidence rates were in Malta (0.25 per 100 000), followed by Italy (0.11 per 100 000).

 

6.3.5.2. Viral infections

 

Measles

 

Measles is an acute illness causes by morbillivirus. The disease is preventable by a vaccine that provides life-long immunity. The elimination of measles by 2010 (interruption of indigenous measles transmission) is part of the strategic plan for measles and congenital rubella infection in the European Region of the WHO.

 

Due to the two-dose vaccination policy, the incidence of measles in Europe has decreased dramatically over the last 10 years from almost 35 per 100 000 per year before 1997 to less than 10 per 100 000 per year after 1998 (Figure 6.6).

 

Figure 6.6. Measles trend in Europe between 1995 - 2004.

 

This drop is mainly due to a sharp decrease in the number of cases in France and in Italy, but the incidence has decreased greatly in most countries over the 10-year period. A recrudescence of measles was observed in the Netherlands (1999–2000), Spain (2003), Poland (1998) and Lithuania (2002). Since 2000 a significant number of cases have still been observed in France, Germany and Italy. The incidence in these countries has fluctuated between five and 42 per 100 000 per year. In the other countries, incidence has fluctuated between one and 10 per 100 000 per year since 2000.

 

In 2005, a total of 1 291 cases were reported by 25 countries, with more than 50% of cases (776) from Germany. The overall incidence in the EU was 0.28 per 100 000 per year and the highest rates per 100 000 were reported by Ireland (2.26) and Germany (0.94). Elimination has not yet been achieved, and few countries were able to maintain an incidence rate below one per 1 000 000 per year during the past few years.

 

Mumps

 

Mumps is caused by the mumps virus. Mumps is preventable by a vaccine.

 

Between 1996 and 2005, there was a generally decreasing incidence until 2002, but since then the number of cases has again been steadily increasing. Various countries experienced peaks in incidence over this 10-year period, notably Poland in 1998 and 2004, Estonia in 1998, France in 1995–96, Italy in 1995–96 and 1999–2000, Latvia in 2000–01, Lithuania in 1999, Malta in 2000, Portugal in 1996–97 and Spain in 1996 and 2000.

 

In 2005, a total of 52 918 cases were reported by 23 countries. The UK, followed by Iceland, reported the highest incidence rates (77.24 and 28.95 per 100 000, respectively). In those countries, mumps mainly affected young adults. The overall incidence in the reporting countries was 17.65 per 100 000 per year.

 

Rubella

 

Rubella is a mild febrile illness affecting both adults and children. The most serious consequence of rubella results from infection during the first trimester of pregnancy, when rubella infection can cause miscarriage, foetal death or severe birth defects. The overall trend of rubella in the last 10 years is declining, with two peaks seen in 1997 and 2001. However, recrudescence was observed particularly in Poland in 1997 and 2001, in Latvia in 1996 and 2002, in Lithuania in 1995 and 1999–2000, Czech Republic in 1998 and 2002, Italy in 1996–97 and 2001–02, Iceland in 1996 and Spain in 1996.

In 2005, a total of 1 498 cases were reported by 22 countries. The overall incidence was 0.51 per 100 000 per year, with Lithuania (3.44 per 100 000) and the Netherlands (2.23 per 100 000) reporting the highest rates. The age and sex distribution varied across countries, and may reflect a variation in the vaccine coverage by sex (some vaccination programmes started in women first) together with a variation in notification (more attention is given to rubella in girls and women).

 

Polio

 

Polio is caused by poliovirus. Childhood immunisation has been an effective preventive measure. In Europe, the last case of flaccid paralysis caused by wild polio was reported by Turkey in November 1998, and in June 2002 the WHO European Region was declared polio free. However, poliovirus imported from endemic countries remains a threat, as demonstrated in 1992–93 when imported polio caused an outbreak of 71 cases with two deaths in an unvaccinated community in the Netherlands. Polio eradication has implications in terms of the vaccination policies of Member States as many are changing from the live vaccine to inactivated vaccines in order to avoid vaccine associated flaccid paralysis.