If you take antibiotics, there’s a good chance you’ll also get diarrhoea.
Antibiotics kill harmful bacteria that cause disease. But they also cause collateral damage to the microbiome, the complex community of bacteria that live in our gut. This results in a profound, though usually temporary, depletion of the beneficial bacteria.
One popular strategy to mitigate the disruption is to take a probiotic supplement containing live bacteria during, or following, a course of antibiotics.
The logic is simple: beneficial bacterial in the gut are damaged by antibiotics. So why not replace them with the “beneficial” bacterial strains in probiotics to assist gut bacteria returning to a “balanced” state?
But the answer is more complicated.
There is currently some evidence that taking probiotics can prevent antibiotic-associated diarrhoea. This effect is relatively small, with 13 people needing to take probiotics for one episode of diarrhoea to be averted.
But these studies have often neglected to evaluate potential harms of probiotic use and haven’t looked at their impact on the wider gut microbiome.
Pros and cons of probiotics
The assumption that there is little downside to taking probiotics was challenged in a recent Israeli study.
The participants were given antibiotics and split into two groups: the first group was given an 11-strain probiotic preparation for four weeks; the second was given a placebo, or dummy pill.
The researchers found the antibiotic damage to the gut bacteria of those in the first group allowed the probiotic strains to effectively colonise the gut. But this colonisation delayed the normal recovery of the microbiota, which remained perturbed for the entire six month study period.
In contrast, the microbiota of the second group returned to normal within three weeks of finishing antibiotics.
This research exposes a perhaps unexpected truth: we still don’t know what types of bacteria are truly beneficial or even what constitutes a healthy microbiome.
The answer is unlikely to be that individual bacterial strains are particularly helpful.
It’s more likely a diverse community of thousands of different types of microbes working together can provide health benefits. This microbial community is as individual as each one of us, meaning there is not just one configuration that will result in health or illness.
So, it’s unlikely that the addition of one or even 11 strains of bacteria in a probiotic could somehow balance this complex system.
A more effective (but less palatable) alternative?
The Israeli study also explored an alternative approach to microbiome restoration.
One group of participants had their own stool collected and frozen prior to antibiotic treatment. It was then re-instilled into their gut at the end of the antibiotic therapy.
This treatment, known as autologous faecal transplantation, was able to restore the microbiome to original levels after just eight days. The other group took 21 days to recover.
This approach has also been shown to effectively restore the gut microbiome following combined antibiotic and chemotherapy treatment. These patients are predictably at risk of serious complications, such as bloodstream infection, as a result of microbiome disruption.
Research currently underway will help us understand whether microbiome restoration with autologous faecal transplantation will translate into tangible benefits for these patients.
But such an approach would not be a realistic option for most people.
Feed the good bacteria
A more practical strategy to aid recovery is to provide the good bacteria in your gut with their preferred source of nutrition: fibre. Fibrous compounds pass undigested through the small intestine and into the colon, where they act as fuel for bacterial fermentation.
So if you’re taking antibiotics or have recently finished a course, make sure you eat plenty of vegetables, fruit and wholegrains. Your gut bacteria will thank you for it.
Lito Papanicolas, Infectious diseases specialist and PhD candidate, South Australian Health & Medical Research Institute and Geraint Rogers, Professor; Director, Microbiome Research, South Australian Health & Medical Research Institute
More than one-third of Australians’ energy intake comes from junk foods. Known as discretionary foods, these include biscuits, chips, ice-cream and alcohol. For those aged 51-70, alcoholic drinks account for more than one-fifth of discretionary food intake.
These are some of the findings from the Nutrition across the life stages report released by the Australian Institute of Health and Welfare today.
The report also shows physical activity levels are low in most age groups. Only 15% of 9-to-13-year-old girls achieve the 60-minute target. The prevalence of overweight and obesity remains high, reaching 81% for males aged 51–70.
The food intake patterns outlined in this report, together with low physical activity levels, highlight why as a country we are struggling to turn the tide on obesity rates.
Not much change in our diets
The report shows little has changed in Australians’ overall food intake patterns between 1995 and 2011-12. There have been slight decreases in discretionary food intake, with some trends for increased intakes of grain foods and meat and alternatives.
The message to eat more vegetables is not hitting the mark. There has been no change in vegetable intake in children and adolescents and a decrease in vegetable intake in adults since past surveys. The new data show all Australians fall well short of the recommended five serves daily. We are are closer to meeting the recommended one to two serves of fruit each day.
Australians are consuming around four serves of grains, including breads and cereals, compared to the recommended three to seven serves.
One serve of vegetables is equivalent to ½ cup of cooked vegetables. For fruit, this is a medium apple; grains is around ½ cup of pasta. A glass of milk and 65-120g of cooked meat are the equivalent serves for dairy and its alternatives, and meat and its alternatives respectively.
The data show a trend of lower serves of the five food groups in outer metro, regional and remote areas of Australia. Access to quality, fresh foods such as vegetables at affordable prices is a key barrier in many remote communities and can be a challenge in outer suburban and country areas of Australia.
There was also a 7-10 percentage point difference in meeting physical activity targets between major cities and regional or remote areas of Australia. Overweight and obesity levels were 53% in major cities, 57% in inner regional areas and 61% in outer regional/remote areas.
The CSIRO Healthy Diet Score compares food intake to Australian Dietary Guidelines. You can use these to see how your diet stacks up and how to improve.
Discretionary food servings
Discretionary foods are defined in guidelines as foods and drinks that are
not needed to meet nutrient requirements and do not fit into the Five Food Groups … but when consumed sometimes or in small amounts, these foods and drinks contribute to the overall enjoyment of eating.
A serve of discretionary food is 600kJ, equivalent to six hot chips, two plain biscuits, or a small glass of wine. The guidelines advise no more than three serves of these daily – 0.5 serves for under 8-year-olds.
Since 1995, the contribution of added sugars and saturated fat to Australians’ energy intake has generally decreased. This may be a reflection of the small decrease in discretionary food intake seen for most age groups.
But across all life stages, discretionary food intakes remain well in excess of the 0-3 serves recommended. Children at 2-3 years are eating more than three servers per day, peaking at seven daily serves in 14-to-18-year-olds. The patterns remains high throughout adulthood, still more four serves per day in the 70+ group.
The excess intake of discretionary foods is the most concerning trend in this report. This is due to the doubleheader of their poor nutrient profile and being eaten in place of important, nutrient-rich groups such as vegetables, whole grains and dairy foods.
Our simulation modelling compared strategies to reduce discretionary food intake in the Australian population. We found cutting discretionary choice intake by half or replacing half of discretionary choices with the five food groups would have significant benefits for reducing intake of energy and so-called “risk” nutrients (sodium and added sugar), while maintaining or improving overall diet quality.
Main contributors to discretionary foods
Alcohol is often the forgotten discretionary choice. The NHMRC 2009 guidelines state:
For healthy men and women, drinking no more than two standard drinks on any day (and no more than four standard drinks on a single occasion) reduces the lifetime risk of harm from alcohol-related disease or injury.
For adults aged 51–70, alcoholic drinks account for more than one-fifth (22%) of discretionary food intake. Alcohol intake in adults aged 51-70+ has increased since 1995. This age group includes people at the peak of their careers, retirees and older people. Stress, increased leisure time, mental health challenges and factors such as loneliness and isolation would all play a part in this complex picture.
Four ways alcohol is bad for your health
Young children have small appetites and every bite matters. The guidelines suggest 2-to-3-year-olds should have very limited exposure to discretionary foods. In, studies the greatest levels of excess weight are seen in preschool years.
Biscuits, cakes and muffins are the key source of added sugars for young children. These are also the top source of energy and saturated fat and a key source of salt in young children. This is the time when lasting food habits and preferences are formed.
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As we age, our bodies inevitably deteriorate. Some changes, like grey hair and wrinkles, are easily visible. Others, like high blood pressure, often go unnoticed, but can be deadly.
Just as our body shows signs of ageing, so does our genome. Damage comes from chemical reactions that alter our DNA, and from errors introduced when it is copied. Our cells protect against these ravages, but these mechanisms are not foolproof and cells gradually accumulate DNA damage over a lifetime.
As a consequence of this damage, your genome is not the same in every cell; you are a patchwork of cells with subtle differences in their DNA. When a cell divides it will pass on these changes, and as they accumulate there is more and more likelihood that there will be consequences.
If these changes – we call them mutations – chip away at the systems that govern cell proliferation and survival, this can lead to cancer.
Our latest research, published today in the journal Blood, provides new clues about how our cells protect their genome and guard against cancer.
Guarding the genome
Nearly 10% of cancers have a familial component. Genes like BRCA1 and TP53 are among the best known cancer susceptibility genes, and both are involved in coordinating the cell’s response to DNA damage.
BRCA1 helps to repair a specific type of DNA damage, in which both strands of DNA are broken. Inheriting a defective BRCA1 gene elevates the lifetime risk of both breast and ovarian cancer.
When DNA repair mechanisms break down, cells can accumulate staggering numbers of mutations, and cancer becomes almost inevitable.
Beyond genetics, a complex mix of environmental and lifestyle factors modify cancer risk.
When we read the genome of a cancer it is possible to attribute mutations to certain types of stress. UV radiation, for example, will fuse certain DNA bases. The UV damage signature is writ large in melanoma, a cancer linked to sun exposure.
Lung cancers from smokers and non-smokers have different mutation patterns because of the action of chemicals in cigarette smoke that attack the DNA.
We can also use this approach to diagnose defective DNA repair, as each defect triggers a characteristic pattern of mutations. In this way, mutation signatures can help us understand why a cancer has developed.
A ticking genetic clock
Smoking, UV radiation and X-rays all damage your DNA, but damage also comes from reactive molecules present within the cell. These molecules are fundamental to the chemistry of life – take water, for example.
Water is a very reactive molecule and can do damage to our DNA. One of the most common mutations, either in cancer or in normal cells, results from water molecules reacting with methylated DNA.
DNA methylation is a small chemical modification that acts as a signpost on top of our genetic code. It helps to control which genes are switched on or off. This fine-tuning is essential for normal development, but methylation also makes DNA more susceptible to damage. Most of these events are quickly repaired, but the damage is unrelenting and some sneak through.
Methylation damage is the most prominent feature of an ageing genome. It’s so pervasive and reliable it has been proposed as a molecular clock that marks ageing. But our new research shows this process occurs more rapidly in some people.
We found and studied three people whose pathways to repair methylation damage had broken down. They all lacked a DNA repair protein called MBD4, which led to a marked accumulation of methylation damage – as though their cells were ageing prematurely.
All three developed an aggressive form of leukaemia in their early 30s, a cancer which usually wouldn’t be seen until the person is in their 60s or 70s.
Methylation damage plays a role in most cancers, but in these cases it was the primary driver of the disease.
While complete inactivation of MDB4 – as occurred in the three participants – is extremely rare, our findings raise the question of how more subtle differences in DNA repair shape cancer risk, particularly in the context of ageing.
Turning back the clock
Ageing contributes to cancer risk in myriad ways. While we’ve focused here on the buildup of DNA damage, our immune system also plays an important role and tends to fade as we get older.
Lifestyle factors – such as obesity, stress and diet – also provide a cumulative risk that builds over a lifetime.
Understanding the interplay between these factors is key to finding strategies that will effectively diffuse the health consequences associated with ageing.
Our research is helping to tease apart the contribution of DNA damage in different disease processes. Our findings suggest that some people accumulate more DNA damage than others – their clocks are ticking a little faster – and measuring these differences may help to spot people at risk of developing cancer, or help match them with more effective treatments.
Ian Majewski, Laboratory Head & Victorian Cancer Agency Fellow, Cancer & Haematology Division, Walter and Eliza Hall Institute and Edward Chew, PhD candidate, Cancer and Haematology Division, Walter and Eliza Hall Institute
In response to the public outcry against the potential for My Health Record data to be shared with police and other government agencies, Health Minister Greg Hunt recently announced moves to change the legislation.
The laws underpinning the My Health Record as well as records kept by GPs and private hospitals currently allow those records to be shared with the police, Centrelink, the Tax Office and other government departments if it’s “reasonably necessary” for a criminal investigation or to protect tax revenue.
If passed, the policy of the Digital Health Agency (which runs the My Health Record) not to release information without a court order will become law. This would mean the My Health Record has greater privacy protections in this respect than other medical records, which doesn’t make much sense.
Changing the law to increase privacy
Under the proposed new bill, state and federal government departments and agencies would have to apply for a court order to obtain information stored in the My Health Record.
The court would need to be satisfied that sharing the information is “reasonably necessary”, and that there is no other effective way for the person requesting it to access the information. The court would also need to weigh up whether the disclosure would “unreasonably interfere” with the person’s privacy.
If granted, a court order to release the information would require the Digital Health Agency to provide information from a person’s My Health Record without the person’s consent, and even if they objected.
If a warrant is issued for a person’s health records, the police can sift through them as they look for relevant information. They could uncover personally sensitive material that is not relevant to the current proceedings. Since the My Health Record allows the collection of information across health providers, there could be an increased risk of non-relevant information being disclosed.
But what about our other medical records?
Although we share all sorts of personal information online, we like to think of our medical records as sacrosanct. But the law underpinning My Health Record came from the wording of the Commonwealth Privacy Act 1988, which applies to all medical records held by GPs, specialists and private hospitals.
Under the Act, doctors don’t need to see a warrant before they’re allowed to share health information with enforcement agencies. The Privacy Act principles mean doctors only need a “reasonable belief” that sharing the information is “reasonably necessary” for the enforcement activity.
Although public hospital records do not fall under the Privacy Act, they are covered by state laws that have similar provisions. In Victoria, for instance, the Health Records Act 2001 permits disclosure if the record holder “reasonably believes” that the disclosure is “reasonably necessary” for a law enforcement function and it would not be a breach of confidence.
In practice, health care providers are trained on the utmost importance of protecting the patient’s privacy. Their systems of registration and accreditation mean they must follow a professional code of ethical conduct that includes observing confidentiality and privacy.
Although the law doesn’t require it, it is considered good practice for health professionals to insist on seeing a warrant before disclosing a patient’s health records.
In a 2014 case, the federal court considered whether a psychiatrist had breached the privacy of his patient. The psychiatrist had given some of his patient’s records to Queensland police in response to a warrant. The court said the existence of a warrant was evidence the doctor had acted appropriately.
In a 2015 case, it was decided a doctor had interfered with a patient’s privacy when disclosing the patient’s health information to police. In this case, there no was warrant and no formal criminal investigation.
Unfortunately, there are recent examples of medical records being shared with government departments in worrying ways. In Australia, it has been alleged the immigration department tried, for political reasons, to obtain access to the medical records of people held in immigration detention.
In the UK, thousands of patient records were shared with the Home Office to trace immigration offenders. As a result, it was feared some people would become too frightened to seek medical care for themselves and children.
We can’t change the fact different laws at state and federal level apply to our paper and electronic medical records stored in different locations. But we can try to change these laws to be consistent in protecting our privacy.
If it’s so important to change the My Health Records Act to ensure our records can only be “unlocked” by a court order, the same should apply to the Privacy Act as well as state-based laws. Doing so might help to address public concerns about privacy and the My Health Record, and further inform decisions about opting out or staying in the system.
Megan Prictor, Research Fellow in Law, University of Melbourne; Bronwyn Hemsley, Professor of Speech Pathology, University of Technology Sydney; Mark Taylor, Associate professor, University of Melbourne, and Shaun McCarthy, Director, University of Newcastle Legal Centre, University of Newcastle
Most adults get around two to three colds a year, and children get even more. In terms of the flu, there are around 3-5 million severe cases of influenza worldwide each year and 290,000 to 650,000 deaths.
The symptoms of a cold and the flu are similar, so it’s hard to tell the difference. But the flu is usually more severe and develops more quickly than a cold.
Colds and flus can be easily passed from person to person through the air, when an infected person coughs or sneezes, and touch, when a person touches an infected surface or object like doorknobs and light switches.
So what’s the difference between colds and flus, and how long should you stay away?
Cold symptoms include a sore throat, cough, runny or stuffy nose, tiredness and headache.
Most people become contagious with cold symptoms one to two days after exposure to a cold virus. These symptoms usually peak two to four days later. The common cold usually lasts about ten days.
There is nothing you can take to shorten the duration of a cold, and most people will get better without needing to see a doctor. But some over-the-counter medications can help alleviate the symptoms. These include anti-inflammatories (to reduce inflammation or swelling), analgesics (to reduce pain), antipyretics (to reduce fever) and decongestants (to relieve nasal congestion).
But be careful you follow the instructions and recommended dosage for these medications. A recent study of US adults who used paracetamol, the active ingredient in many cold and flu medicines, found 6.3% of users exceeded the maximum recommended daily dose. This mostly occurred during the cold and flu season.
Common symptoms of the flu include fever (a temperature of 38°C or higher), cough, chills, sore throat, headache, runny or stuffy nose, tiredness and muscle aches.
An infected person can spread the flu for five to seven days after becoming infected. The infectious period can begin 24 hours before the onset of symptoms. This means you can spread the flu without even knowing you’re sick.
Influenza viruses can cause mild to severe illness in people of all ages. Most people will fully recover within one to two weeks and won’t require any medical attention. Similar to a cold, people can take some over-the-counter medications and other remedies to help alleviate symptoms.
But some people can become acutely unwell with the flu. They may require antiviral medication and, in severe cases, hospitalisation. Those at high risk include pregnant women, children, the elderly, and people with certain medical conditions such as HIV/AIDS, asthma, diabetes and heart and lung diseases.
The flu virus strains that circulate usually change every year, so the best way to prevent getting the flu is to get the annual flu vaccine. The vaccine is moderately effective and recommended for adults and children over the age of six months. Some common side effects may occur, such as temporary soreness, redness and swelling at the injection site, fever, headache, muscle aches and nausea.
Avoid passing it on
If you feel unwell, stay home from work or school and rest (and get plenty of fluids) until you feel better. If you’ve had a fever, stay home for at least 24 hours after the fever has broken.
When you go back to work or school, you may still be infectious, so avoid passing the virus on by:
regularly washing your hands with soap and water for at least 20 seconds and drying them properly – if soap and water are not available, use an alcohol-based hand sanitiser
practising good cough and sneeze etiquette: cover your mouth and nose with a tissue or your upper shirtsleeve when you cough or sneeze, and throw away used tissues immediately
not touching your eyes, nose and mouth
frequently cleaning the surfaces and objects you’ve touched.
Last week I had a shocking cold. Blocked nose, sore throat, and feeling poorly. This made me think about the countless vitamins and supplements on the market that promise to ease symptoms of a cold, help you recover faster, and reduce your chance of getting another cold.
When it comes to the common cold (also called upper respiratory tract infections) there is no magic cure (I wish) but some supplements may deliver very minor improvements. Here is what the latest research evidence says.
Health Check: can you treat the common cold?
For the average person, taking vitamin C does not reduce the number of colds you get, or the severity of your cold.
In terms of how long your cold lasts, some studies have looked at people taking vitamin C every day, while others have focused on participants taking it once they develop a cold.
In 30 studies comparing the length of colds in people regularly taking at least 200 milligrams of vitamin C daily, there was a consistent reduction in the duration of common cold symptoms.
However, the effect was small and equates to about half a day less in adults, and half to one day less in children. These types of studies also found a very minor reduction in the amount of time needed off work or school.
Among studies where vitamin C was only started once a cold had developed, there was no difference in duration or severity of a cold.
There are some risks to taking vitamin C supplements. They can increase the risk of kidney stones in men, and shouldn’t be taken by people with the iron storage disease haemochromatosis, as vitamin C increases iron absorption.
Although in the general population vitamin C has no impact on the number of colds people get, there is an exception. For people who are very physically active – such as marathon runners, skiers and soldiers exercising in very cold conditions – vitamin C halved their chance of getting a cold.
A few studies have also found some benefit from vitamin C supplements of at least 200 milligrams a day for preventing colds among those with pneumonia.
However, taking vitamin E supplements in combination with a high intake of vitamin C from food markedly increased the risk of pneumonia.
A review of studies testing zinc supplements in healthy adults found starting daily supplements of at least 75 milligrams within 24 hours of the onset of a cold shortened the duration by up to two days or by about one-third. It made no difference to the severity of the cold.
There was some variability in the results across trials, with insufficient evidence related to preventing colds. Researchers suggested that for some people, the side effects such as nausea or a bad taste from zinc lozenges might outweigh the benefits.
Take care to stop zinc supplements as soon as your cold resolves because taking too much zinc can trigger a copper deficiency leading to anaemia, low white blood cell count, and memory problems.
Only one study has tested the impact of garlic on the common cold. Researchers asked 146 people to take garlic supplements or a placebo daily for 12 weeks. They then tallied the number and duration of their colds.
The group that took garlic reported fewer colds than those who took the placebo. The duration of colds was the same in both groups, but some people had an adverse reaction to the garlic, such as a rash, or found the garlic odour unpleasant.
Because there is only one trial, we need to be cautious about recommending garlic to prevent or treat colds. We also need to be cautious about interpreting the results because the colds were tracked using self-report, which could be biased.
In a review of 13 trials of probiotic supplements that included more than 3,700 children, adults and older adults, those taking supplements were less likely to get a cold.
Their colds were also likely to be of shorter duration and less severe, in terms of the number of school or work days missed.
Most supplements were milk-based products such as yoghurt. Only three studies used powders, while two used capsules.
The quality of the all the probiotic studies, however, was very poor, with bias and limitations. This means the results need to be interpreted with caution.
Echinacea is a group of flowering plants commonly found in North America. These days you can buy echinacea products in capsules, tablets or drops.
A review of echinacea products found they provide no benefit in treating colds. However, the authors indicated some echinacea products may possibly have a weak benefit, and further research is needed.
Yep, I’ve saved the best until last.
In a novel experiment on 15 healthy adults, researchers measured the participants’ nasal mucus flow velocity – our ability to break down and expel mucus to breathe more clearly. They tested how runny participants’ noses were after sipping either hot water, hot chicken soup or cold water, or sucking them through a straw.
Sipping hot water or chicken soup made participants’ noses run more than cold water, but sipping chicken soup worked the best. The researchers attributed this to the chicken soup stimulating smell and/or taste receptors, which then increased nasal mucus flow.
Another study on chicken soup found it can help fight infection and recovery from respiratory tract infections.
Other researchers have shown comfort foods, such as chicken soup, can help us feel better.
It’s peak flu season. You’re cold, rugged up and squashed on public transport or in the lift at work. You hear a hacking cough, or feel the droplets of a sneeze land on your neck. Will this turn into your third cold this year?
No matter how much we try to minimise our exposure to respiratory viruses, it’s far more difficult in winter when we spend so much time in close proximity to other people.
On top of this, viruses tend to be more stable in colder and drier conditions, which means they stick around longer.
The common cold is caused by more than 200 different viruses, the most common of which are rhinoviruses (rhino meaning nose). Rhinovirus infections tend to be mild; you might get a sore throat and a head cold lasting just a few days.
Influenza, or the flu, is generally caused by type A or B influenza viruses. The flu is far more aggressive and often includes a fever, fatigue and body aches, in addition to all the classic cold symptoms.
When it comes to getting sick, there’s always an element of bad luck involved. And some people, particularly those with young children or public transport commuters, are likely to come into contact with more viruses.
But you may have noticed that illness often strikes when you’re stressed at work, not sleeping properly, or you’ve been out partying a little too much. The health of our immune system plays an important role in determining how we can defend against invading cold and flu viruses.
How the immune system fights viruses
Your skin and saliva are key barriers to infection and form part of your immune system, along with cells in every tissue of your body, including your blood and your brain.
Some of these cells migrate around to fight infection at specific sites, such as a wound graze. Other cells reside in one tissue and regulate your body’s natural state of health by monitoring and helping with the healing process.
The cells that make up your immune system need energy too, and when you’re low on juice, they’ll be on low-battery mode. This is when our natural immune defences are weakened and normally innocuous bugs can begin to cause strife.
Our immune system requires a lot of energy to defend our bodies. Feeling tired and achy, overheating, and glands swelling are all signs that our immune system is busy fighting something.
Explainer: how does the immune system work?
Boosting our natural defence system
Our immune system has evolved to naturally detect and eliminate viral infections. And we can actively strengthen our immunity and natural defences by looking after ourselves. This means:
getting adequate sleep. Sleep deprivation increases the hormone cortisol, which suppresses immune function when its levels are elevated
exercising, which helps the lymphatic system, where our immune cells circulate, and lowers levels of stress hormones
eating well and drinking enough water. Your immune system needs energy and nutrients obtainable from food. And staying well hydrated helps the body to flush out toxins
- not smoking. Smoking, or even secondary smoke, damages our lungs and increases the vulnerability of our respiratory system to infection.
Educating our immune system
Natural defences aren’t always enough to keep us safe and we need the help of flu vaccinations.
Vaccines are designed to educate an army of B and T cells which make up your adaptive immune system. This arm of your immune system learns by exposure and provides long-term immunity.
These T and B cells need a bit of time from the initial influenza exposure before they can be activated. This activation lag time is when you feel the brunt of the flu infection: lethargy, body aches, extreme fatigue and unable to get off the couch for a day or two.
To overcome this delay and protect people before they are exposed to potentially harmful flu strains, flu vaccination introduces fragments of the influenza virus into the body, which acts like prior exposure to the bug (without actual infection).
Seasonal vaccines are designed to match currently circulating strains and target those strains before you’re infected.
You can still catch the influenza virus if you are vaccinated. But because of this pre-education, the symptoms will likely be milder. The immune system has been trained and the army of B and T cells can move into action quicker.
Already have a cold or the flu?
If you’ve been sniffling and sneezing your way through winter, be comforted by the fact that these bugs are strengthening your immune system. Our body remembers the particular strain of rhinovirus or influenza we get, so it can recognise and mount a stronger defence if we encounter it again.