Gone are the days when we became little pink pin cushions on only a few occasions as children; the new schedule is quite complex with immunisations against 17 different microorganisms (18 if you are a girl) and that’s not counting the fact that the Streptococcus pneumoniae vaccine actually covers 13 different subtypes of the bacterium. The schedule consists of 16 different injections plus 2 oral and 8 intranasal vaccines. That’s a lot of vaccines so it is important to understand why we are subjecting our children to this hefty regimen.
NB you can download a free POSTCARD size of this table for inside your copy of Microbiology Nuts & Bolts.
The “D” is for diphtheria. Corynebacterium diphtheriae causes the infection diphtheria, a severe upper respiratory tract infection which introduces toxins into the body that can cause neurological and cardiac complications. The mortality from diphtheria even with treatment is 5-10%. Diphtheria epidemics used to cause havoc across the country, and still do in countries which don’t have a vaccination program. It was one of the most feared infections in the pre-vaccination era, nowadays Microbiologists may see only 1 or 2 cases in their career if they are particularly unlucky!
The “T” is for tetanus. Clostridium tetani causes tetanus, a toxin mediated infection causing spasm in muscles leading to muscle damage, fractures, breathing difficulties, cardiac arrhythmias and neurological damage. The mortality of tetanus even with treatment is 10%, and this goes up in the elderly and frail. Clostridium tetani can enter the body through wounds which are contaminated with dirt (known as tetanus prone wounds) however the source of the infection is often unapparent and may be completely missed. I have seen tetanus following road traffic accidents, intravenous drug abuse and gardening injuries including the “classical” simple prick from a rose thorn!
The “aP” is for Bordetella… yeah that one doesn’t work! The “aP” is actually for “acellular pertussis” but you could remember it as “and pertussis!” Bordetella pertussis causes the condition pertussis or whooping cough. This is one of the two most scary clinical conditions I have ever seen (the other appears later in this blog!). Pertussis is especially severe in neonates and young infants. Infants get a spasmodic cough, they cough and cough and cough before being unable to breathe then (hopefully) they take a sudden breath which gives the characteristic “whoop”. Neonates and very young infants just go navy blue, stop breathing and their hearts stop beating… it is truly one of the most terrifying things to see in clinical medicine, even with the ability to intubate and ventilate these children. The mortality from pertussis in children less than 60 days old is about 1% but more than this have long term neurological damage (some studies estimate 2%)… but this is a lot higher if you aren’t able to provide urgent supportive care. Without vaccination it is likely that paediatric intensive care services would be quickly overwhelmed in an epidemic.
The IPV is for inactivated polio vaccine. Polio Virus is an Enterovirus which causes a neurological infection characterised by flaccid paralysis in about 1% of infections. This may not sound like much but the paralysis, when it occurs, often extends to involve the respiratory muscles and the child cannot breath. In this situation if the child is not mechanically ventilated they die (remember the iron lung?). Approximately two thirds of patients with flaccid paralysis have long term weakness and the overall mortality in patients with flaccid paralysis in the pre-vaccination era (pre-1960s) was 5-10% but could go as high as 50% if the respiratory muscles were involved.
Hib infection is the other scariest thing I have seen in clinical medicine. In the pre-vaccination era when I was a student and junior doctor in 1897 (…tee hee editorial “error” …1997) we used to dread a patient with Hib epiglottitis being admitted. This was usually a childhood disease and the children were at imminent risk of blocking off their airway and stopping breathing. You had to tread very carefully around the patient making sure not to upset them in any way whilst you waited for an anaesthetist who could perform an emergency tracheostomy to be available in case things went wrong! You didn’t even try and examine the child, maybe you just got the parents to waft some oxygen in the child’s general direction whilst you got everything in place. With good careful management and the availability of tracheostomy the mortality is less than 3%; it was still blooming scary though! Most deaths from Hib occurred before the child reached hospital. As if epiglottitis wasn’t bad enough, Hib also used to be one of the most common causes of meningitis, septic arthritis, osteomyelitis and pneumonia.
All round it’s a bad bug and one of the few subjects I have actually published about in the medical literature… although it looks like even I would have to pay for access to my own publication these days…
Hepatitis B Virus causes infectious hepatitis. It is very infectious with 1 in 3 people exposed to blood from an infectious person developing the infection. Up to 90% of infants infected at birth, and 10% of adults, go on to develop chronic infection. Of those with chronic infection, up to 25% die from cirrhosis or hepatocellular carcinoma. The vaccine not only prevents infection but is also considered an anti-cancer vaccine.
Streptococcus pneumoniae infection
S. pneumoniae is the most common cause of pneumonia in the UK as well as being a common cause of meningitis, septic arthritis and osteomyelitis. The current vaccine in the UK covers 13 different serotypes of the bacterium which account for the majority of cases in children. Another benefit to the vaccine is that by preventing these strains of bacteria circulating in children the vaccine also prevents them being transmitted to adults; so everyone benefits and the rate of infection goes down in children and adults. This is sometimes referred to as herd immunity; by stopping a microorganism circulating in the population even those who haven’t been vaccinated are protected by the rest of the “herd”.
Neisseria meningitidis infection
Many people are now aware of the devastating infections caused by Neisseria meningitidis; meningitis and septicaemia. What you may not know is that the UK was one of the first countries in the world to introduce a vaccine against it (MenC). We normally are the last to introduce something new, waiting to see what happens in other countries before we do anything, but for Men C back in 1992 there was an outbreak at Southampton University and the vaccine was introduced rapidly to bring this under control... how do I know?... I was at Southampton University at the time.
We now have vaccines against all of the common types of N. meningitis seen in the UK, A, B, C, Y and W. The MenB vaccine is relatively new but this winter was the first year I have known where I only saw a few patients with meningococcal septicaemia and all except one were adults… vaccines are really quite amazing!
Okay, the rotavirus vaccination may be a bit controversial, let’s see what you think. In the UK rotavirus gastroenteritis is a self-limiting diarrhoeal infection and although it’s not pleasant having a child with diarrhoea, the treatment is supportive, providing adequate fluids and hydration often orally using those horrible tasting oral rehydration solutions (although I find flattened fizzy pop works best, as all kids will drink that!). Yearly there are about 12,700 hospital admissions but mortality is very uncommon (approximately 1 in a million cases). So if rotavirus gastroenteritis is not as dramatic as pertussis or Hib why vaccinate against it?
The argument for rotavirus vaccine is predominantly an economic one across the developed world. Many parents each year miss work because their children have rotavirus diarrhoea. It is estimated that before the vaccination was introduced there were about 650,000 cases of rotavirus infection every year. At best each of these children would miss a week of school which means 5 lost days of work per parent. This equates to over 3 million lost working days. The vaccine is reported to be about 70% effective at preventing rotavirus gastroenteritis saving the UK economy over 2 million lost working days a year; added to this is the nearly 10,000 saved hospital admissions a year as well. Financially this is a great vaccine.
Okay, so that’s our first year of vaccinations done. Next blog I’ll look at the rest of the childhood immunisations, including some that are still slightly controversial even if the infections they prevent are not.