Overview of Vaccines
There are several safe and very effective vaccines to protect against major causes of bacterial meningitis. The vaccines work by stimulating the immune system to create protective antibodies against the bacteria. Then if the bacteria get into the body, the immune system is ready to defend against them. There are many different strains of bacteria that cause meningitis. It is necessary to protect yourself against each one because the antibodies resulting from each vaccine are specific. A vaccine for one bacterium or strain will not protect against other strains.
There are two types of vaccine: polysaccharide and conjugated. The polysaccharide vaccines are not effective in infants less than 2 years of age. The conjugated vaccines, on the other hand, are effective at all ages, starting in infants as young as 2 months of age. Conjugated vaccines are known to offer a longer duration of immunity than polysaccharide vaccines. Conjugated vaccines against the meningococcus, pneumococcus, and Haemophilus influenzae type b, the three major causes of bacterial meningitis, are now part of the routine childhood immunization program in Canada and many other countries.
Vaccines against Meningococcus
Conjugated Vaccines (Polysaccharide linked to protein)
Conjugated ACYW135 Vaccine
Menactra®
Conjugated C Vaccines
Menjugate®
NeisVac C®
Meningitech®
Polysaccharide Vaccines
ACYW135 (Menomune®)
AC (Mencevax AC®)
Vaccines Against Pneumococcus
Conjugated Vaccines (Polysaccharide linked to protein)
Prevnar®
Polysaccharide Vaccines
Pneumo23®
Pneumovax23®
Pnu-Immune23®
Vaccines Against Haemophilus influenzae type b
Conjugated Vaccines (Polysaccharide linked to protein)
Act-HIB®
Meningococcus Bacteria
There are several strains of Meningococcus. The most common are called Groups A, B, C, Y and W135. There is no vaccine for Group B.
In Canada between 1995 and 2003, Group B strains caused 42% of cases or an average of 81 cases per year. The frequency of group B cases does not vary very much from year to year. However, the number of cases caused by group C, Y and W135 varies from year to year. While Group C has traditionally been dominant, the disease landscape has changed in recent years with an increasing numbers of Groups Y and W-135 being observed. Over the 11 year period, the proportion of cases caused by each serogroup was: group B 43.3, group C 38.0, group Y 13.9 cases, and group W135 4.8
Serogroup |
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| Year | B | C | Y | W135 |
| 1995 | 127 | 101 | 24 | 8 |
| 1996 | 100 | 92 | 22 | 2 |
| 1997 | 104 | 69 | 36 | 10 |
| 1998 | 62 | 36 | 32 | 5 |
| 1999 | 92 | 63 | 18 | 12 |
| 2000 | 67 | 106 | 25 | 8 |
| 2001 | 85 | 182 | 30 | 9 |
| 2002 | 92 | 80 | 39 | 9 |
| 2003 | 81 | 47 | 41 | 18 |
| 2004 | 87 | 56 | 27 | 14 |
| 2005 | 96 | 38 | 24 | 16 |
| Total | 993 | 870 | 318 | 111 |
| Cases per year | 90.3 | 79.1 | 28.9 | 10.1 |
Because of this variation in groups from year to year, a broad-spectrum vaccine protecting against all vaccine-preventable strains is the most effective.
Children across Canada are routinely vaccinated with one of the conjugated group C vaccines (Menjugate C® NeissVac C® or Meningitech®) that protect only against disease caused by group C.
Conjugated A-C-Y-W135 vaccine protects against all four vaccine-preventable strains of meningococcal disease i.e. A,C,Y and W-135. It can be used in children 2 years of age and older previously vaccinated against Group C, adding protection against the other strains of Meningococcus. It can also be used in children 2 years of age and older who have not previously been vaccinated with any meningococcal vaccine.
In PEI and New Brunswick and in new recruits in the Canadian Forces, Conjugated A-C-Y-W135 vaccine has replaced the group C conjugate vaccine for routine use in adolescents in the provincial immunization program. It is hoped that other provinces will do the same.
Pneumococcus Bacteria
There are over 80 types of this bacterium. They are primary causes of pneumonia, bronchitis, ear and sinus infections. Less frequently they cause meningitis.
The conjugated pneumococcal vaccine contains 7 different conjugated polysaccharides which protect against the 7 most common types causing disease in children less than 5 years of age.
Haemophilus influenza type b
Also called Hib, this was the most common cause of bacterial meningitis until 1992. It also caused other serious infections including pneumonia, skin and joint infections. Infants from 6 to 18 months and children under the age of 5 were most commonly infected. Hib infections are rare in Canada because since 1992 infants are routinely immunized with Hib vaccine.
In Canada, the conjugated Hib vaccine is given to infants at 2, 4, 6, and 18 months of age as part of a combined 5-in-1 vaccine containing diphtheria toxoid, tetanus toxoid, acellular pertussis vaccine, and inactivated polio vaccine.
