By Dr Eddy Bajrovic*
“But, I had that vaccine when I was a kid. Surely I don’t need it again?”
It’s a plaintive plea we hear every day in Travelvax Australia’s clinics, as well as from prospective travellers who call our travel health advisory service (1300 360 164) seeking guidance on the potential health risks of their upcoming overseas trip.
When it comes to the immunisations we routinely had – or should have had – in childhood, it’s a common misconception that they last for life.
So, it often comes as a shock when we have to tell adults that they may well need a booster or two to protect them from some of the diseases they thought they were no longer at risk of.
Ironically, many of the diseases which once killed youngsters in their hundreds have indeed been eliminated in Australia.
However, some have made a comeback around the world in recent years, especially measles and whooping cough (also called pertussis). Not just in developing regions of the world, but in industrialised countries in North America and Western Europe, too.
Australia hasn’t escaped epidemics of these vaccine-preventable diseases. We recorded more than 140,000 cases of whooping cough between 2008 and 2012, while measles rates are currently at record levels. The 304 measles cases recorded to date this year is already almost double last year’s total.
Infected travellers behind outbreaks
The big increases have been partly due to a small percentage of parents refusing or delaying immunisation of their children. But, the other big contributor has been unvaccinated or non-immune travellers becoming infected overseas and returning home to pass on the disease to family, friends and the wider community.
Even polio, currently the target of an intense and costly global eradication campaign, is defying attempts to eliminate it from its last strongholds. So concerned is the World Health Organisation that international travellers, including Australians, visiting Pakistan, Cameroon, Syria and Equatorial Guinea, (where the disease remains active), for more than a month require proof of vaccination to return home, or fly to another destination.
For doctors, a pre-travel medical consultation is an ideal opportunity to ensure that a travelling patient – regardless of age – is up to date with the routine childhood immunisations before moving on to discuss vaccines that may be recommended or required for the particular destination/s.
So, just how long do the routine, recommended and required vaccines last before they need a booster?
ROUTINE VACCINES
Routine immunisations are those that form the scheduled vaccines given to eligible infants and young children under Australia’s free childhood vaccination program. The length of protection listed in the sections below assumes full courses of the respective vaccines have been completed previously.
Polio – 10 years.
Diphtheria/tetanus – 10 years.
Whooping cough (Pertussis) – 10 years.
Measles/mumps/rubella – ‘Long-term’. (A high proportion of Australia’s recent measles cases have involved unvaccinated young adults. Anyone born during or after 1966 should receive 2 doses of measles-containing vaccine a month apart before departure, if they do not have evidence of previous receipt of two doses of MMR vaccine, or serological evidence of protection for these diseases, the Australian Immunisation Handbook* advises.)
Meningitis – 5 years for conjugate, 3 years for polysaccharide.
RECOMMENDED VACCINES
These include the vaccinations commonly recommended for travel to developing regions to protect against food- and water-borne diseases, and blood-borne or respiratory infections.
Hepatitis A – ‘long-term’ 20 years or longer, if two doses received. Only 1-3 years for a single dose of vaccine (includes the adult combination Hep A & B vaccine).
Hepatitis B – ‘long-term’ - 20 years or longer after full completed course (3+ doses)
Injectable Typhoid – 3 years
Influenza – 6-12 months
Oral Typhoid – 3 capsules – 3 years, 4 capsules – 5 years
Tick-borne Encephalitis – 3 years
Oral Cholera vaccine – 2 years
Japanese encephalitis – there are 2 vaccines: IMOJEV’s protection lasts at least 5 years for adults, or perhaps longer (to be advised); Jespect’s protection lasts 1 year.
Rabies – ‘long-term’ (at least 10 years, booster required sooner if at higher or regular risk of exposure such as occupational exposure). Also a further 2 doses of vaccine is required post-exposure (i.e. after an ‘at-risk’ contact involving potential exposure).
REQUIRED VACCINES
The only required immunisation is yellow fever, although Muslims seeking a visa to attend the annual Hajj are required to show proof of vaccination against Meningococcal meningitis (4 strains), while the seasonal influenza vaccine is recommended.
Yellow fever – ‘long-term’. (Currently, a booster is still required every 10 years. This may change when Australia adopts a WHO recommendation issued last year. It advised that vaccinated travellers no longer require the booster because of the long-term protection the vaccine has been shown to provide over more than 80 years of use. However, until then, 10-year boosters are required by Australians visiting yellow fever-infected countries in South America or Africa.)
Why every vaccine ‘counts’
A delay in completing a primary course of vaccines or missing a booster dose doesn’t mean the schedule must be restarted from the beginning. Every vaccine counts – as long as the recommended doses were given at no LESS than the minimum recommended intervals.
This is because of the power of ‘immune memory’, the capacity of our immune system to respond more rapidly and strongly to each subsequent exposure to a vaccine’s protective antigens.
The only exceptions are the oral typhoid and oral cholera vaccines. Experts advise the primary course be started again if a follow-up dose is missed.
Most vaccines can be given at the same time in different sites on the body without adversely affecting their respective immune responses or increasing the (generally low) risk of an adverse event.
It may not sound ideal, but having vaccines at one time actually ensures that they get done. It also simplifies the pre-travel vaccination process by cutting down on the number visits to the doctor.
Again, there’s an exception: live vaccines should be administered during the same visit or separated by a month.
Give yourself enough time
One of the main reasons that travellers are advised to start their pre-travel preparations at least 6 weeks before departure is to avoid these complications and to give them time for any tests that might be suggested to be performed and reviewed, and so vaccinations can be completed at least 2 weeks before the trip.
Studies over many years have shown that vaccines from different manufacturers which protect against the same disease are virtually interchangeable, including the following diseases: Tetanus, diphtheria, polio (OPV and IPV), Hepatitis A, rabies, Measles/Mumps/Rubella (MMR), seasonal influenza, and Hib.
Different brands of the meningococcal and typhoid Vi polysaccharide vaccines are interchangeable for repeat doses only, while there is no firm data for the interchangeability of rotavirus, pneumococcal conjugate, Human papilloma virus (HPV), or the Japanese encephalitis vaccines.
A travel clinic is your best option
While 6 weeks pre-travel lead-time is ideal, it is never too late to benefit from immunisation. Indeed, accelerated schedules are available for some vaccines involving a course of shots.
Even if the full course is not completed, a vaccine given just prior to travel develops its effectiveness quickly enough to offer some protection against a disease picked up soon after arriving at an overseas destination.
If you see a GP rather than a travel clinic for immunisations prior to travel, it’s VITAL that any vaccines you source from a pharmacy are kept in a ‘cold chain’ – that is, the doses remain between 2 and 8 degrees Celsius at ALL times. If the ‘chain’ is broken and the vaccine gets either too hot or too cold, it can no longer be considered viable.
Travel clinics keep the vaccines you might need for your trip on site ready to be given during your consultation – another good reason to seek advice from a doctor experienced in travel medicine 6 weeks before you leave.
*Dr Bajrovic is the Medical Director of Travelvax Australia.
For more advice on vaccinations that may be recommended or required for your journey, call Travelvax Australia’s obligation free travel health advisory service on 1300 360 164 (toll-free from landlines). You can also make an appointment for a pre-travel medical consultation at a Travelvax clinic to receive vaccines, any medication required, accessories, and personalised advice tailored to your itinerary and your medical history.