Flu and Cold


The runny nose, sore throat or bunged up feeling of a cold is caused by one of many viruses that infect the upper part of the breathing system (upper respiratory tract). Although a cold can make you feel miserable, in most people they are self limiting. This means the body fights off the infection and cure comes without the need for specific medical treatment.

Influenza - or flu - causes similar symptoms to a cold but tends to be a more severe illness. Although it is also self-limiting in most people, flu can be dangerous for people who are frail or have a weakened immune system. Generally, there are two peaks for influenza occurrence in Hong Kong - one in February and the other in July, but this can be influenced by imported cases of flu from other countries.

Causes of cold and flu

The viruses responsible for colds are spread from person to person as droplets in the air from sneezing or coughing, or from touching infected surfaces then transmitting the viruses from the hands to the mouth. Handshakes or touching a door handle are possible routes for transmission of cold viruses. Infected people can spread the viruses from two days before the illness and up to four days after the symptoms start. Colds can occur all year round but are more common in the winter months.

People living in residential or nursing homes, and people with the following conditions are at risk:

  • Asthma
  • Chronic chest problems such as chronic bronchitis and emphysema
  • Diabetes
  • Heart disease
  • Kidney diseases and kidney failure
  • People with reduced immunity, such as people with HIV or people who have had their spleen removed

Symptoms of cold and flu

Colds - the virus multiplies in the soft, warm surfaces found in the nose, throat, sinuses, the windpipe (trachea) and the breathing tubes (the bronchi). The main symptoms are blocked or runny nose, sneezing, sore throat and cough. There may also be a fever, aching muscles and fatigue. The symptoms usually last for a week.

Flu - These are the same as colds but the muscle aching is usually more severe and the fatigue may last for a few weeks after the illness has cleared up. To most healthy adults, flu can be just like a nasty cold. However, young children, the elderly and people with certain chronic medical conditions are susceptible to potentially serious complications. These are mostly related to a secondary bacterial infection of the lungs (pneumonia) or of the ears, nose and throat. In children under about six years old, fits - known as febrile convulsions - can occur as a result of the high body temperature.

If the following symptoms develop with a cold, you should consult a doctor promptly:

  • Severe vomiting or diarrhea
  • Earache
  • Difficulty breathing
  • Skin rash
  • Uncontrollable cough
  • Cough with green sputum - phlegm
  • Extreme lethargy or drowsiness

Treatment of cold and flu

There is no cure for colds or flu. Antibiotics, which do work to kill bacteria, do not work on viruses. However, home treatment can help to relieve the symptoms and ensure a speedy recovery.

(I) Home treatment

  • Drink plenty of fluids to prevent dehydration
  • Avoid tobacco smoke
  • Decongestants such as pseudo-ephedrine may clear congestion. Ask your pharmacist for advice on products that contain a decongestant
  • Steam inhalations with menthol or eucalyptus, or herbal products such as camomile, may help. Take care with the hot water
  • Eating a balanced diet with plenty of fruit and vegetables is sensible
  • Rest. Avoid strenuous exercise, as this can increase the chance of catching a secondary bacterial infection. Contrary to the advertising claims for some cold and flu medicines, if you are unwell with a heavy cold and, especially, flu, carrying on as normal is not advisable

(II) Medication

For people in general good health, who are not elderly, no specific medical treatment - apart from the home care suggested above - is required for flu. For vulnerable groups, where it is important to prevent complications or spread, prescription only medicines may be required.

For adults, paracetamol, aspirin or ibuprofen can help to relieve fever and pain. Always follow the instructions carefully and take care not stay within the safe daily doses. It is easy to accidentally exceed these by using more than one product (tablets, capsules, a hot lemon drink…) containing the same active ingredient such as paracetamol For children under 12 years old aspirin can be dangerous (in rare cases, it can cause Reyes syndrome). It should also be avoided in older children and adolescents. Childrens formulations of paracetamol (eg Calpol) and ibuprofen (Nurofen Junior) are available.

There are several anti-viral treatments, taken as tablets or as an inhaler (similar to the ones used for asthma). They have been shown to reduce the duration of flu but only by around one day, and then only if treatment is started within two days of the onset of the illness. Doctors are not currently routinely prescribing antiviral medicines for flu.

Antibiotics may be given to treat any bacterial infections such as a chest infection, ear infection or sinusitis.

Prevention of cold and flu

  • Isolation of people with colds and flu to prevent it spreading to other people, if practical
  • Regular hand washing and immediate disposal of tissues
  • Aim for a healthy lifestyle a balanced diet, rich in fruit and vegetables, and regular (preferably daily) physical activity
  • Do not smoke - smokers are more likely to catch a cold

Having a flu vaccine each year significantly reduces the chance of catching the illnesses. It is recommended for people with chronic health conditions or BMI≧30, the elderly and children who are more likely to experience complications from the seasonal flu.

Last Updated : Aug 2017
Please note that all medical health articles featured on our website have been reviewed by Quality Healthcare doctors. The articles are for general information only and are not medical opinions nor should the contents be used to replace the need for personal consultation with a qualified health professional on the reader’s medical condition.
Source: Bupa website www.bupa.com.hk​

Flu and Cold

What is influenza?

​Influenza, also known as the “flu” is a contagious disease that is caused by the influenza virus. It commonly attacks the respiratory tract of human (nose, throat and lungs). Unlike common cold, flu may cause severe illness and life-threatening complications in some people.

What are the signs and symptoms of the flu?
Influenza is an illness that can come on suddenly and may include the following symptoms:

  • Fever
  • Headache
  • Tiredness (can be extreme)
  • Dry cough
  • Sore throat
  • Nasal congestion
  • Body aches

Occasionally, some patients and children may also suffer from gastro-intestinal symptoms, including nausea, vomiting and diarrhoea.
What are the complications of the flu?
Some of the complications include secondary bacterial pneumonia, dehydration, and myocarditis. Flu may also worsen some pre-existing chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

Children may get sinus and ear infections as complications from the flu. The elderly and those with chronic medical conditions are at highest risk for developing serious complications.
How do I know if I have the flu?

​It is sometimes difficult to tell the difference between the flu and other viral diseases based on symptoms alone. Tests may help to confirm or exclude that an illness is influenza or other viral illnesses. In addition, a doctor’s assessment is important to determine whether someone has complications resulting from the flu.

What causes the flu?
The Influenza virus causes the flu. There are 3 types of Influenza viruses- Types A, B and C Influenza. Types A and B viruses cause epidemics of disease. Influenza Type C usually causes a mild respiratory disease and are not thought to cause epidemics.

A flu vaccination can prevent illness from certain strains of Influenza Types A and B depending on the yearly composition but does not protect against Type C.
What is bird flu and swine flu?
Influenza A viruses are found in many animals, including ducks, chickens, geese, pigs, wild birds, whales, horses, and seals. Wild birds are the primary natural reservoir for all subtypes of influenza A viruses and are thought to be the source of influenza A viruses in all other animals. Influenza B viruses circulate widely only among humans.

While it is unusual for people to get influenza infections directly from animals, human infections and outbreaks caused by certain animal influenza viruses have occasionally been reported.

In 1997 and early 2003, human infections with bird or avian influenza A (H5N1) virus were reported by Hong Kong Department of Health. The World Health Organization (WHO) also announced a global swine flu (H1N1 pandemic) during the period of 11th June 2009 till 10th August 2010. Although H1N1 is no longer the dominating flu strain, it will not disappear altogether. Rather, it would be seen as behaving more like the seasonal flu activity.
What do the newspapers mean when they refer to the types of influenza viruses as “H5N1” or “H1N1”?

​Influenza A viruses are divided into “subtypes” based on 2 proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N). There are 15 different “H” subtypes and 9 different “N” subtypes. A combination of different “H” and “N” proteins on the surface of the influenza virus describes different types of influenza A viruses.

What is “Stomach Flu”?

​Many people use the term “Stomach Flu” to describe illnesses with nausea, vomiting, or diarrhoea. Many different viruses, bacteria or even parasites can cause these symptoms. While vomiting, diarrhoea and being nauseous can sometimes be related to the flu, particularly in children, these problems are not commonly the main symptoms of influenza.

What is the treatment for Influenza?

For healthy individuals, seasonal influenza is usually a self-limiting illness with recovery in 2-7 days.

Medications for symptomatic relief such as decongestants, cough remedies, and simple pain relievers including paracetamol can help you feel better while your body's immune system fights off the infection. Antiviral medications e.g. oseltamivir (marketed as TAMIFLU®), if started in the first two days after your symptoms start, can shorten the length of your illness. These will need to be prescribed by your doctor depends on disease severity and other risk assessments.

Since seasonal influenza is a viral infection, antibiotics would not be effective unless the flu is complicated by bacterial infection, such as pneumonia, sinusitis or ear infection.

Are there any tests to diagnose influenza?
A number of tests can help to diagnose influenza. These tests include taking samples from a throat swab, nasal wash or nasal aspirates and are done within the first 3- 4 days of your illness. Rapid Diagnostic Tests for Influenza (RIDTs) can be conducted in clinic and results can be obtained in as fast as 15 minutes with accuracy up to 90% or higher*. These tests are useful when a doctor needs additional information to help determine diagnosis and treatment decision.

*Reference: CAPILIATM Flu Neo (manufactured by TAUNS Laboratories, Inc. Japan) Product Information.
What should I do for my family members or myself if we get the flu?
You are recommended to do the following:

  • Rest
  • Drink plenty of fluids
  • Avoid using alcohol and tobacco (e.g. cigarettes and cigars)
  • Take medication to relieve the symptoms of flu
  • Seek medical advice if there is high fever, if you or your family members have chronic medical conditions, if the member of the family is very young or elderly, or if you suspect complications of influenza

Influenza is caused by a virus, so antibiotics would not help unless you develop a secondary bacterial infection.
How long is the incubation period (How soon will I get sick if I am exposed to the flu virus)?

​The time from when a person is exposed to flu virus to when symptoms begin is about 1-4 days, with an average of about 2 days.

When is the influenza season in Hong Kong?

​In Hong Kong, influenza is most prevalent in January-March and July-August.

How is influenza spread?
The flu is transmitted, or spread, when a person who has the flu coughs, sneezes, or spits, thus sending the droplets with flu virus into the air, where other people may inhale the virus. The virus then enters the nose, throat, or lungs of a person and begins to multiply, causing symptoms of influenza.

Influenza may also be spread when a person touches a surface that has flu viruses on it- such as a door handle - and then touches his or her nose or mouth.
How contagious is influenza?
A person can spread the flu even one day before he or she feels sick. Adults can continue to pass the flu virus to others for another 3 to 7 days after symptoms start. Children can pass the virus for longer than 7 days.

Symptoms start 1 to 4 days after the virus enters the body. Some persons can be infected with the flu virus but have no symptoms. During this time, those persons can still spread the virus to others.
Who are the people at high risk for developing complications from influenza?
The best way to prevent the flu is to get an influenza vaccine (flu shot) before the flu season. A yearly flu shot is recommended for the following groups of people who are at increased risk for serious complications from or transmission of the flu:

  • Persons aged >50 years
  • Children aged 6 months to 5 years
  • Residents of nursing homes and other long-term care facilities that house persons of any age who have long-term illnesses
  • Adults and children > 6 months of age who have chronic heart or lung conditions, including asthma
  • Adults and children > 6 months of age who need regular medical care or had to be in a hospital because of metabolic diseases (like diabetes), chronic kidney disease, obese individual with body mass index > 30, or weakened immune system (including immune system problems caused by medicine or by infection with human immunodeficiency virus or HIV)
  • Children and teenagers (aged 6 months to 18 years) who are on long-term aspirin therapy and therefore could develop Reye’s Syndrome after the flu
  • Pregnant women at all stages
  • Healthcare workers and other workers in a healthcare work environment including clinics, hospitals and elderly homes
  • Poultry workers, pig farmers and pig-slaughtering industry personnel
Is there a way to prevent infection?
The following are suggested ways to prevent catching the flu virus:

  • Maintain good personal and environmental hygiene
  • Keep hands clean and wash hands properly
  • Wash your hands when there are respiratory secretions on them, e.g. after sneezing.
  • Cover your nose and mouth while sneezing or coughing and dispose of nasal and mouth discharge properly. Do not spit.
  • Good body defense helps to prevent influenza infection. This can be achieved through a balanced diet, regular exercise, adequate rest, reduced stress and avoid smoking.
  • During the “flu season”, it is better to avoid crowded public places where the ventilation is not good.
  • By far the best way to prevent the flu is for individuals, especially for those at high risk, to get a flu shot each year.
Is there a vaccine against influenza?

​Yes there is a vaccine. It is referred to as an influenza vaccine or a flu shot. The influenza vaccine is prepared according to the strains prevalent in the community each year, as recommended by the World Health Organization. There are trivalent and quadrivalent flu vaccine available.

What is trivalent and quadrivalent flu vaccine?

​The trivalent flu vaccine is designed to protect against three different flu viruses: two influenza A viruses and one influenza B virus. The quadrivalent flu vaccine is designed to protect against four different flu viruses: two influenza A viruses and two influenza B viruses.

Why was the quadrivalent flu vaccine developed?

​For years, flu vaccines were designed to protect against three different flu viruses (trivalent). This included an influenza A H1N1 virus, an influenza A H3N2 virus and one B virus. Experts had to choose one B virus, even though there are two very different lineages of B viruses that both circulate during most seasons. This meant the vaccine did not protect against the group of B viruses not included in the vaccine. Adding another B virus to the vaccine aims to give broader protection against circulating flu viruses.

How effective is the influenza vaccination in preventing influenza?

​The flu vaccine is 70-90% effective in preventing influenza among healthy adults if it is administered at least 2 weeks before exposure and if there is a good match between the vaccine and the influenza strain causing illness. Vaccine effectiveness is lower for older persons, but can significantly reduce their chances of serious illness or death from influenza.

Who should get an influenza vaccination?
Anyone who wants to lower his or her chances of getting the flu can get a flu shot. In particular, people at high risk for complications of the flu and people in close contact with them (including household members) should get the vaccine. The Scientific Committee on Vaccine Preventable Diseases under the Centre for Health Protection (CHP) of the Department of Health recommends seasonal influenza vaccination for personal protection against clinical influenza for all persons except those with known contraindications. Moreover, nine categories of people are recommended to receive vaccination against seasonal influenza:

  • Pregnant women at any gestational stage
  • Elderly persons living in residential care homes
  • Long-stay residents of institutions for the disabled
  • Persons aged 50 years or above
  • Persons with chronic medical problems including those obese individual with BMI>/=30
  • Health care workers
  • Children aged six months to five years
  • Poultry workers
  • Pig farmers and pig-slaughtering industry personnel
Can I have an influenza vaccination if I am pregnant? Is it safe for me to have influenza vaccination if I am breast-feeding?
Pregnancy can alter the immune system, and affect a mother’s cardiovascular and respiratory function (heart and lung function). These changes may place a pregnant woman at increased risk of developing complications from the flu. One study showed that amongst the pregnant women, the group who did not receive flu vaccination is 22 times more likely to suffer from complication of flu than the group who had received flu vaccination.

Because the flu shot is made from inactivated viruses (the viruses are killed), many experts consider flu shots safe during pregnancy. According to the recommendations from the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC) of United States as well as from the Centre for Health Protection (CHP) of Hong Kong, inactivated influenza vaccine can be used for all stages of pregnancy. There is no evidence indicating inactivated influenza vaccine is teratogenic.

As it takes 2 weeks for antibodies to develop after vaccination, all pregnant women are recommended to get a flu shot before the flu season, especially for those who have medical problems that increase their risk for complications from the flu.

It is safe to get a flu shot even if you are breastfeeding.
Who should NOT get an influenza vaccination?
The following groups should not get a flu shot before consulting with their doctor:

  • People who have severe allergy to eggs (ovalbumin and chicken protein). This includes individuals who develop swelling of the tongue, lips or experience acute respiratory distress or collapse after ingestion of eggs.
  • People who have had a severe reaction to a flu shot in the past
  • People who have previously developed Guillain-Barre Syndrome (GBS) in the 6 weeks after getting a shot (a disease of the nervous system resulting in muscle weakness or paralysis)
  • People with known allergy to Gentamicin Sulphate or any other excipients of the vaccine - Polysorbate 80, Octoxinol 9, Haemagglutinin, Sodium Deoxycholate, Cetyltrimethylammonium Bromide, Octylphenol Ethoxylate and Formaldehyde.
  • People with a moderate to severe acute illness, with or without fever.
  • People with problems with immune system as the immune response may be diminished.
Why do I need to get vaccinated every year?
Flu viruses change from year to year. Because of this, you need to be aware of the following:

The natural protection or immunity you develop after catching a particular strain of influenza virus does not necessarily protect you against another strain of influenza virus.

Secondly, a vaccine made against one flu virus may not protect you against a different strain. That is why the influenza vaccine is updated each year to include current strains of the year.

A third reason to get influenza vaccination every year is that after you get a flu shot, your immunity to the flu declines over time and may not provide adequate protection after one year.
When should I get vaccinated?

​​Flu vaccinations for the year generally become available in the second half of the year, before winter arrives in the Northern Hemisphere.

How long does it take for my body to develop antibodies against influenza after I am vaccinated?

​Once you get a flu shot, it takes about 2 weeks for antibodies to develop in the body and provide you with protection against influenza virus infection. In the meantime, you are still at risk of catching the flu. That is why it is much better to get vaccinated before the flu season starts.

Can I catch influenza even after being vaccinated?
Yes. The ability of an influenza vaccination being able to protect a person depends on
2 things:

  • The age and health status of the person getting the vaccination and
  • The similarity or “match” between the virus strains in the vaccine and those viruses in circulation.

When the “match” between the vaccine and the circulating strains of viruses is close, the flu vaccine prevents influenza in about 70-90% of healthy persons younger than age 65 years.

Will the influenza vaccine protect me against catching a cold and other illnesses?

​​Influenza vaccine only protects against illness caused by influenza viruses, and not against other conditions such as fever, colds or gastrointestinal complaints caused by other viruses.

Will the influenza vaccine give me the flu?

​The influenza vaccine is made from inactivated or killed flu viruses, and does not cause flu illness.

What are the side effects that could occur with an influenza vaccination?
  • Soreness, redness, or swelling where the injection was given
  • Fever (low grade)
  • Aches

These problems may occur soon after the injection and should usually last no more than 1 to 2 days.
Can severe problems occur?
Life-threatening allergic reactions are rare. These reactions tend to occur among persons with a severe allergy to eggs, because the viruses used in the influenza vaccine are grown in chicken eggs. People who have had a severe reaction to eggs or to flu shot in the past, should not be vaccinated before consulting a doctor.

Guillain–Barré syndrome (GBS) - This condition is characterised by fever, nerve damage and muscle weakness. A study done in 1976 suggests that 1 out of 1 million vaccinated persons may be at risk of GBS associated with the vaccine. Most people eventually recover, but some may have permanent nerve damage.

What is the global experience about the safety of Flu vaccines?
The most frequently reported adverse events were local discomfort at injection sites and headaches. For Guillain–Barré syndrome, there was no direct link found with the flu vaccine in most cases. There is also no evidence that flu vaccine leads to fetal losses.

Locally, the Centre for Heath Protection has monitored the significant adverse events of seasonal influenza vaccination and the details can be found at the following link:

How is a rapid test carried out and how long does it take?

​​Rapid diagnostic tests for influenza (RIDTs) can identify different kinds of influenza A and B viral infections. Doctors will collect a nasal swab specimen for screening. RIDTs can detect influenza viral antigens even at an early stage of infection and take only 15 minutes to give the results.

Should we take the rapid test once we have found ourselves having influenza symptoms?

​​In fact, it is difficult to distinguish influenza from illnesses caused by other viruses simply by symptoms. If necessary, patients can take the rapid test to identify whether they have any influenza infection and eliminate the possibility of having other viral infections. The test is meant to facilitate accurate diagnosis and make good use of the 48-hour golden period for treatment to reduce the risk of complications.

Please note that all medical health articles featured on our website have been reviewed by Quality Healthcare doctors. The articles are for general information only and are not medical opinions nor should the contents be used to replace the need for personal consultation with a qualified health professional on the reader’s medical condition.
Source: Bupa website www.bupa.com.hk​

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