Facts and Figures About Vaccines
Vaccines and ChildrenFIGURES: Each year, 26.3 million children who could be vaccinated against bacterial diseases that might kill them do not get their vaccine. India, for example, has 9.2 million children who are not vaccinated against any common infectious disease. In developing countries, some vaccines are too expensive, some children live in remote areas and vaccination crews do not reach them, in others children live in war zones where vaccination is sometimes impossible.
FACT: If all children could be immunised, a fifth of all children who die globally each year could be saved. Infectious diseases still claims millions of children's lives.
Vaccinating Against Whooping CoughFIGURES: The vaccine against whooping cough, a childhood infection caused by the bacterium Bordetella pertussis, is one of the most successful. In the UK in the 1950s, 100 000 children every year caught whooping cough and some of them died. After the vaccine was introduced, the number of cases reduced dramatically. In 2007, whooping cough was reported in only 150 children under the age of four and a half. If we stopped vaccinating babies, whooping cough would come back. It is only continued use of the vaccine that keeps it under control.
Diphtheria VaccineFACT: Diphtheria vaccine has been given in three stages to babies aged two, three and four months in the UK for many years. It is given at the same time as the vaccine against whooping cough and meningitis (the Hib vaccine) and against the viral infections polio and tetanus. Like whooping cough, diphtheria could reappear if vaccination did not continue. When the former Soviet Union broke apart at the end of the 1980s, diphtheria vaccination did stop for a while and in 1991, there was an outbreak of over 2000 cases.
Vaccinating Against MeningitisFACT: Bacterial meningitis is one of the most dangerous bacterial infections anyone can catch. It can be fatal within 24 hours. Three bacteria are responsible; Neisseria meningitidis, Haemophilus influenzae B and Streptococcus pneumoniae. Since the introduction of the Hib vaccine against Haemophilus influenzae B, cases of meningitis due to this bacterium rarely occur.
Cholera VaccineFACT: The Dukoral cholera vaccine is available for health workers and travellers to regions of the world where cholera is a big risk. However, it is only partially effective and does not have 100% protective efficiency. It is not used for people who live in areas where cholera outbreaks occur as it would not be cost effective. In the future, it is hoped that research will produce a more effective cholera vaccine that will provide enough protection to be used in vulnerable populations.
Vaccinating Against TuberculosisFACT: The BCG vaccine against tuberculosis has been used for many years. While it prevents deaths from TB in children under 10, and can protect against some of the effects of the infection on the brain, the BCG vaccine has had no real effect on the incidence of TB globally. It is not really understood why this is, but it seems that the vaccine helps but does not prevent infection. Trials of new vaccines are in progress and there are high hopes for a new vaccine, maybe around 2020.
Typhoid VaccineFIGURES: Typhoid is a serious public health problem and causes around 30 million cases of illness every year worldwide. It kills between 500 000 and 600 000 people every year and is most serious in children and young adults.
FACT: As well as improving sanitation and living conditions, two vaccines are available for the control of typhoid. One is the Ty21 vaccine that is taken orally, the other is a polysaccharide vaccine that needs to be given by injection. Neither are 100% effective – more like 80% efficient at best but they are useful for travellers and people at risk and to reduce transmission in areas where the bacterium that causes typhoid, Salmonella typhi, is common.
Future Vaccines Against Bacterial DiseaseFACT: Many of the successful vaccines that have been developed are against viral diseases, such as measles and smallpox. It is easier to target an infection caused by a very simple pathogen. Bacteria are much more complex and interact with the human body in many different ways, so producing vaccines is more difficult.
FACT: New vaccines for many bacterial diseases are being actively researched, including one against the superbug, MRSA (methicillin-resistant Staphylococcus aureus). This could be available by about 2015.
FACT: It may be possible to develop protective vaccines against bacterial diseases by genetically engineering bacteria such as those of the Salmonella species that actively invade human cells. Some Salmonella do this but only for a few cycles, and this does not cause illness. If genes from other, more pathogenic bacteria such as Streptococcus pneumoniae could be put into these safe 'carrier' bacteria, they might induce a good immune response and protect against pneumonia.