When effective vaccines are introduced into the standard immunisation schedule, we almost forget how horrible that disease was. What parent now is petrified of polio? This month sees the introduction of a new vaccine, and, surprisingly, hardly anyone has heard of the infection that it will help eradicate. Pneumococcus.
What Is Pneumococcal Disease?
We have lived through the arrival of Haemophilus influenzae type b (Hib) vaccines. There used to be 700 serious Hib infections with 15 deaths a year in Australia. Now as a result of Hib immunisation, there are no longer children dying or being left disabled due to Hib meningitis. As one illness is nearly annihilated, the next most common killer on the list moves up and comes to attention. That bug is now pneumococcus.
Pneumococcus is now responsible for more deaths world wide than any other bug. We may not have heard of it, but we have certainly heard of the illnesses and infections it can be responsible for. For example it is responsible for most cases of meningitis in children under two years old.
It lives harmlessly in the noses of many people. However it can invade the body and cause meningitis, blood infections (bacteraemia), pneumonia or middle ear infections. It particularly affects the under five-year-olds and those over 60. Australian aboriginal children living in the outback have the highest recorded rate of infection in the world. Ear infections and discharging ears are very common in this group of children.
Non-indigenous Australian children are most at risk in their first two years. The risk is higher if they are in childcare, have parents who smoke or have recently had a middle ear infection. Ten to 15% of under two-year-olds who get it in their blood get meningitis.
In Australia in the 5 years up to 1998, there were nearly 1000 children hospitalised with pneumococcal infections. Forty four per cent of the hospitalised children had meningitis. Twenty-five children died.
Has The Need For A Vaccine Increased?
Although pneumococcus is a frequent cause of illness and death, interest in preventing it dropped when penicillin became available. Penicillin was very good treatment. However as for most bugs, pneumococcus has become more and more resistant to antibiotics.
In Australia, 25% of pneumococci have a worrying resistance to penicillin, 16% to the antibiotic used in penicillin for allergic people and some are resistant to many antibiotics.
The frequent use of antibiotics in children for non-bacterial infections promotes this. It allows the pneumococcus living harmlessly in the child's nose to become resistant to antibiotics. When the bug is then passed to another child, penicillin won't work.
This is why doctors should only prescribe antibiotics for respiratory infections likely to be due to bugs, not viruses and to use the simple ones, not the big guns or new ones. Antibiotic resistance contributes to the difficulty in treating these serious infections. In spite of our high standard of medical care, a child who gets pneumococcal meningitis has a 10% chance of dying.
How Was The Vaccine Developed?
Pneumococcus comes in many varieties. These are called serotypes. There are ninety different ones, all recognised by the sugars on their capsule. The capsule makes it harder for our immune systems to gobble up the bug. The big number of serotypes involved made it hard to make vaccines. However a few bugs are the commonest offenders.
So vaccines have been made, using the sugar (polysacccharide) capsule of these ones, to teach our immune system to recognise and annihilate them. In Australia, this polysaccharide vaccine is provided free to all Aboriginal and Torres Strait Islanders over 50. It is recommended for all over 65 year olds but only provided free to this group in Victoria.
How Does The New Vaccine Work?
The polysaccharide vaccine currently available includes 23 different serotypes. However infants under two-years-old are not good are responding to vaccines to bugs protected by capsules. That has been a difficulty as these are the children most at risk.
Now this has been overcome in the same way as it was with Hib vaccine. The sugar marking the individual pneumococcus has been tacked onto a protein that helps the immune system recognise it. Young children do get good protection from this new type of vaccine.
Not only that but unlike the non-conjugated vaccine, the carriage of bugs in the nose is decreased. This is good news as where there are outbreaks of pneumococcal infection, for instance in childcare, there have not been good ways of stopping the nasal carriage. However, there are theoretical concerns that this may allow serotypes not included in the vaccine to move in and colonise the nose. However this has not yet been shown to be a problem.
Are There Any Side Effects?
Local reactions, swelling, redness, tenderness at the vaccine site are common in the first two days after vaccination. So far in the tens of thousands of children who have been vaccinated, there was only one more worrying reaction, a child who briefly became floppy.
How Effective Is The New Vaccine?
The effectiveness against potentially fatal pneumococcal infection is around 90%. It also has around a 60% protective effect against pneumococcal middle ear infections.
How And When Will It Be Made Available?
The new conjugated vaccine is likely to be licensed in Australia very soon. Australian Aboriginal children stand the most to gain. They have extremely high rates of infection and live in a country where the new vaccine could be afforded.
It can be given at the same time as other vaccines at the two, four and six month vaccination visits. Older children will need fewer doses - only one or two for those over 12 months.
In the first instance, it will probably not be provided free of charge on the standard schedule. Parents will need to pay for it. It is likely to be expensive, around $100 an injection. However for babies going into care, or whose parents smoke, or who have other health problems (especially recurrent ear infections or children who have had pneumonia) it will be particularly valuable.
For any child, prevention is better than cure. Better a nail in the coffin of a bug than of a child.
By Patricia McVeagh. Dr McVeagh is a Consultant Paediatrician and well-known children's health advocate. She is the co-author of Growing Healthy Children and a popular speaker on children's health issues, particularly nutrition.