Part 2 – Its generally complicated – what you need to know about all of those ‘little pricks’
There are many vaccines and keeping track of them all is difficult. This week’s article described the main ways in which germs make people sick and how the vaccines to protect us from them are made, and about the systems we use to keep track of the vaccines we have had and how public health specialists monitor infectious diseases.
The Australian Immunisation Register (AIR) is a national register of all immunisations given to people in Australia. This includes the immunisations given as a part of the national immunisation programme (childhood vaccinations, school immunisations, and vaccines given to older people and people who need to be immunised for specific reasons). Vaccines given for reasons such as travel are also recorded in the AIR. If you are interested in the National Immunisation Strategy 2018-2024 you can read about it here (https://www.health.gov.au/resources/publications/national-immunisation-strategy-for-australia-2019-to-2024). The AIR started in 2016, and grew from the Australian Childhood Immunisation Register (ACIR), a national systems which started in 1996. You can find your own AIR records through MyGov, of from your vaccine provider (but maybe not in the middle of a clinic!). The information on the AIR is very helpful for your health care providers, as it can assist in thinking about illness you might have.
A list of diseases currently preventable through immunisation and information about them is available through this link (https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases). Some of these vaccines are for the prevention of diseases in travellers and are only recommended if you are travelling to certain areas. COVID/ SARS Cov-2 has not yet been added to this list, but certainly will be soon.
Every microorganism (germ) is different. Vaccines, and immunisation schedules, are complicated because the causes of infectious diseases all work differently. As technology and understanding of infectious diseases has become more sophisticated, and over time science has evolved too, advice that was current 50, 40, 30, and even five years ago changes as our understanding changes.
Some microorganisms (germs) cause illness by producing a toxin – a poison – as by-products of their life-cycle which can damage your vital organs, so that the vaccines include weakened toxins (called ‘toxoids’). Many people will remember needing to have tetanus anti-toxin after a major injury to help negate the effect of possible tetanus infection toxins. Diphtheria is another example of a toxoid vaccine. The germs which cause illness this way are mainly bacteria. Some bacterial infections can be treated with antibiotics.
Other microorganisms, the viruses, cause illness by finding a home inside cells where they reproduce, which damages or kills these cells. There are antiviral medications for treating some viruses, but none can be treated with antibiotics.
There are even more groups of germs which can cause infections, including fungi (candida for example) and a wide variety of parasites, for which various treatments are available.
However, prevention is a lot better than cure, and we are lucky to be alive at a time when vaccines are available to stop many infectious diseases in their tracks. Vaccines work by getting our bodies to recognise the microorganisms (or the toxins they produce) as damaging to us and making the correct, specific antibodies to ward off future infection.
Vaccines have historically been made by making the relevant microorganisms either very weak (‘live attenuated vaccines’), or killed through heating or freezing (‘inactivated vaccines’), so that they cannot reproduce, but your body recognises them as foreign and makes an antibody response. Some vaccines make use of whole microorganisms (such as MMR – measles, mumps and rubella), and some only a part (such as pertussis, or whooping cough). MMR is an example of a live attenuated vaccine, and protection from polio is through an inactivated vaccine.
One group of diseases have been harder to make vaccines for, because the germs which cause them have an impenetrable coating which hides the antigen, a bit like a tiny version of an easter egg hiding chocolate (but nothing like as nice). In the last 20 or so years vaccines have been developed for these diseases by bolting on a bit of the coating to another antigen that is already known to be good at making a good immune response. This group of vaccines, called conjugated vaccines, include meningococcal vaccines and vaccines for various kinds of pneumonia.
Last week this column included information about the mRNA COVID vaccines, using an even newer technique, involving getting our own immune system to ‘read’ and make an antibody response to a fragment of the SARS CoV-2 (COVID) germ’s genetic code, and then destroying the fragment totally.
Some diseases are followed using specific tracking systems, such as the FluTracker website for ‘flu, which was very successful in showing the reduction in flu in 2020, due to all of the things we all did to stop the spread of COVID, as well as high immunisation rates. You can join this group for weekly updates and even see exactly what is happening in Corner Inlet at https://info.flutracking.net (spoiler alert – no flu is happening in postcode 3960!).
How do we know that vaccines work? Well, we have a couple of systems to tell us. The first of these is the communicable diseases notification systems. Tracking and tracing cases of diseases which must be notified to health departments is not new, and certainly did not begin with COVID – it just had to have a major upgrade for the pandemic. Although some folks believe these things are kept secret, the numbers of cases of each of these diseases are published regularly, and you can see that for countries with reliable immunisation systems the cases of vaccine preventable diseases is very low, and drop for diseases when new specific vaccines are added, such as when meningococcal vaccine was added to the Australian schedule. You can find out the list of disease for Australia and information about where they come from at the Communicable Diseases Network Australia (CDNA) here (https://www1.health.gov.au/internet/main/publishing.nsf/Content/cda-cdna-index.htm). There are similar websites all over the world; for Victoria see https://www2.health.vic.gov.au/public-health/infectious-diseases, and for a worldwide perspective you can start at https://www.who.int/data/gho. In fact, you can find out this information for most countries.
However, to make sure that the right response happens quickly when needed, sometimes booster shots are needed. With new information and experience over the years advice about vaccine boosters has changed. This advice is also different for each vaccine – for some boosters are needed, and for others not. Advice is also updated when there are changes to the ways that vaccines are made. Many of us can remember a time when we had to have tetanus vaccine booster and polio shots every 10 years. But over time science has shown us that once you have had six polio doses there is no need for more. Similarly, once you have had six doses with tetanus there is no need for more unless you have a major injury – your very clever immune system will make a good response even if you be unlucky enough to injure yourself with a nasty open wound – accidents do happen unfortunately. However, we need to have flu vaccine every year because parts of the influenza viruses change every year and our immune systems do not recognise the new bits.
There is no difference in your antibody response from wild infection compared with vaccinated and immunised, and with some – such as the COVID vaccine – people make a better antibody response to the vaccine compared with recovering from the infection. So you are much better protected by having vaccines than recovering from any of these truly horrible, dangerous diseases. Stopping diseases which can make people so sick is definitely a very good idea!