Ten years had passed since Dr Ginni Marsberg woke up with flu for the first time, but she remembered clearly how it felt.
"I felt like I was hit and run over by a truck. I could not work, and I could not get out of bed," she said.
The few days she needed to recover was significant, because as a mother and a general practitioner who runs her own clinic, pens a magazine column, and serves as a medical advisor for a radio and morning TV show in Australia, she is not used to taking sick days.
"Now, I would do anything to not go through it again," she said. "I have gotten a flu shot every year since then."
Before that, even after practising medicine for almost a decade, Dr Marsberg had never been vaccinated. She did not think she needed it.
"I was so healthy I almost never got sick ... and because I run, I eat healthily, and I don't drink or smoke, I was just convinced that I was above the flu," she recalled.
The massive bout of flu she had brought her down to earth. "It was then I realised that anybody can get a flu."
Mrs A, a pregnant woman who consultant infectious disease physician Dr Christopher Lee encountered in his hospital's emergency room not too long ago, wasn't so lucky.
Despite being in intensive care and treated with anti-viral medications, she succumbed to respiratory problems brought about by her bout of influenza.
Dr Marsberg was infected by an influenza virus strain that caused seasonal influenza at the time, while Mrs A was affected by the pandemic influenza A(H1N1) virus strain.
What these two cases demonstrate is that influenza can cause serious sickness and even deaths, whether it is seasonal one or one involved in a pandemic.
The different outcomes, however, may be more affected by factors that make Mrs A more vulnerable to the complications of influenza than the timing of her illness.
"For most of us, influenza may mean being sick for a couple of days. But for people with co-morbidities, influenza may cause more serious complications," said Dr Lee. "Mrs A's co-morbidity was her pregnancy," he explained.
Dr Marsberg was in Kuala Lumpur to speak at the launch of an intradermal flu vaccine a few months ago. However, the message she and other experts, like Dr Lee and lecturer at the Universiti Malaya department of medical microbiology Prof Datin Dr Hamimah Hasan, would like to send out to the general public is that it is better to prevent influenza than treat it later.
"We want people to know that the flu is preventable. No one should die from flu," said Prof Hamimah.
Pandemic vs Seasonal
Pandemic vs seasonal influenza
As the 2009 influenza A(H1N1) pandemic slowly fade from our collective memories, little things like hand sanitiser dispensers at shopping malls still remind us of the virus that made over six million people sick and killed a little more than 18,000 worldwide.
Yet, we often overlook the fact that seasonal influenza (or seasonal flu), which in WHO estimations result in about three to five million severe illness every year, has always been around.
Seasonal flu and a pandemic flu differ in that seasonal flu generally occurs in a predictable pattern. Health experts already know, roughly, the kind of viruses that would most likely circulate during a flu season (temperate countries usually have it during winter while tropical countries experience peaks in influenza cases during wet or colder months).
Due to this predictability, we are usually able to get a vaccine that protects against the top three virus strains the WHO thinks would be circulating before the flu season starts.
On the contrary, a novel virus usually causes a pandemic, and many of us are not exposed to it before. As our immune system has no recollection of how to fight the virus, a lot more people may get sick, and a vaccine against the new strain of influenza virus may take up to six months to develop.
Another marked difference between seasonal and pandemic flu is the demographics of those who are more likely to develop serious complications as a result of an infection.
In seasonal influenza, people who are very young, very old, women who are pregnant, or those who have chronic conditions like asthma, heart disease or diabetes, will be the ones that are most likely to develop complications.
In a pandemic, healthy adults are also at increased risk of developing complications.
In March 2009, when the influenza A(H1N1) virus first spread in Mexico, it was new to most of our immune systems. Despite travel restrictions, school closures, and efforts to discourage public gatherings, there was a worldwide spread. However, a vaccine arrived about six months later and it was soon under control.
Today, as many people have been exposed to the influenza A(H1N1) virus, it has become one of the viruses that contributes to seasonal influenza, particularly in the South East Asian region.
"Although we are in the post-pandemic phase, the virus is still there," Dr Lee said. "Up till today, we still get patients who are admitted with severe pneumonia as a result of A(H1N1) infections," he noted.
Doc, am I having the flu?
Doc, am I having the flu?
While the symptoms of seasonal flu and the pandemic flu may differ slightly, both are usually characterised by acute high fever (more than 38 degrees Celcius), cough and sore throat. Other symptoms, such as muscle ache, joint pain, headache, fatigue are also common.
Unlike the common cold, people who come down with flu usually do not see or feel it coming. They could be feeling very well in the morning and suddenly have a high fever in the evening. Also, the symptoms are usually much worse.
"With the common cold, you might be able to go to work after taking some medications. With the flu, it is very likely that you can't," said Prof Hamimah.
These symptoms may be obvious when an adult has it, but when they appear in young children, they may be overlooked as they are common symptoms in children.
However, as influenza almost always causes diarrhoea and vomiting in children, parents should take note when their children's high fever is also accompanied by these two symptoms.
For instance, if a child is having a high temperature and diarrhoea, and appears to avoid drinking (indication of a sore throat) and walking (indication of sore legs), it is highly likely that he is having a flu, says Dr Marsberg.
During the Influenza A(H1N1) pandemic, the Malaysian Health Ministry had advised that anyone who with flu-like symptoms (high fever, cough and sore throat) should seek medical advice, stay home, avoid contact with others, drink lots of fluids, eat nutritious foods and maintain good ventilation in shared household areas.
Those who have co-morbities or underlying conditions that put them at higher risk of developing complications are advised to take extra care to practise good personal hygiene, avoid people who are coughing or sneezing, and see a doctor immediately if they developed flu-like symptoms.
On top of that, the ministry also advised those who have difficulty in breathing, purplish or bluish lips (often due to a lack of oxygen in the blood), cough that produces blood or blood-streaked sputum, persistent chest pain, diarrhoea and vomiting, or fever persisting beyond or recurring after three days, to seek medical help immediately.
These recommendations still apply after the pandemic.
"If you have flu-like symptoms and signs that it may be severe, see a doctor," said Dr Lee. "But if you don't, and don't have co-morbidities, just look after yourself, drink enough water and rest in bed. Things will normally get better within two days or a little more.
"However, if you don't feel better after two days and instead feel worse, it is wise to see a doctor," he explains.