Pneumococcal infections

17 min read

What are pneumococcal infections?

Pneumococcal infections are caused by the Streptococcus pneumoniae (S. pneumoniae) bacterium. They can be mild or severe. There are more than 90 different strains of S. pneumoniae bacteria, which are known as serotypes.

S. pneumoniae enters the human body through the nose and mouth.


symptoms of a pneumococcal infection
can vary depending on the type of infection you have. Common symptoms include a high temperature (fever) of 38°C (100.4°F) or above, aches and pains, and a headache.

Types of pneumococcal infection

Pneumococcal infections usually fall into one of two categories:

  • non-invasive pneumococcal infections – these occur outside the major organs or the blood and tend to be less serious
  • invasive pneumococcal infections – these occur inside a major organ or the blood and tend to be more serious

These are described in more detail below.

Non-invasive pneumococcal infections

Non-invasive pneumococcal infections include:

  • bronchitis – infection of the bronchi, the tubes that run from the windpipe down into the lungs
  • otitis media
    – ear infection
  • sinusitis
    – infection of the sinuses

Invasive pneumococcal infections

Invasive pneumococcal infections include:

  • bacteraemia – a relatively mild infection of the blood
  • septicaemia (
    blood poisoning
    ) – a more serious blood infection
  • osteomyelitis
    – infection of the bone
  • septic arthritis
    – infection of a joint
  • pneumonia
    – infection of the lungs
  • meningitis
    – infection of the meninges, the protective membranes surrounding the brain and spinal cord

Who is at risk?

People with a weakened immune system are most at risk of catching a pneumococcal infection. This may be because:

  • they have a serious health condition, such as HIV or diabetes, that weakens their immune system
  • they are having treatment or taking medication that weakens their immune system, such as

Other at-risk groups include:

  • babies and young children under two years of age
  • adults over 65 years of age
  • people who misuse alcohol

Read more about the

causes of pneumococcal infections

Cases of invasive pneumococcal infection usually peak in the winter during December and January.

Treating pneumococcal infections

Non-invasive pneumococcal infections are usually mild and go away without the need for treatment.

More invasive types of pneumococcal infections can be treated with

, either at home or in hospital.

Read more about

how pneumococcal infections are treated

Pneumococcal vaccines

There are two different types of pneumococcal vaccine used:

  • pneumococcal conjugate vaccine (PCV), which is given to all children under two years of age as part of the childhood vaccination programme
  • pneumococcal polysaccharide vaccine (PPV), which is given to people aged 65 years or over and others who are at high risk

The PCV protects against 13 types of S. pneumoniae bacteria and the PPV protects against 23 types. It is thought that the PPV is around 50-70% effective at preventing more serious types of invasive pneumococcal infection.

Read about pneumococcal vaccination and when pneumococcal vaccination is used.


The outlook for pneumonia in people who are otherwise healthy is good, but the infection can lead to serious complications in people who are very young, very old or have another serious health condition.

However, due to the introduction of the PCV in 2002, the number of people dying from complications that arise from pneumonia has fallen to around 7%.

The outlook for other types of invasive pneumococcal infections such as bacteraemia is generally good, although there is about a one in 20 chance that bacteraemia will trigger meningitis as a secondary infection.

Symptoms of a pneumococcal infection

If you have a pneumococcal infection, your symptoms will vary depending on the type of infection you have.

Some common symptoms include:

  • a high temperature (fever) of 38°C (100.4°F) or above
  • chills
  • sweats
  • aches and pains
  • headache
  • a general sense of feeling unwell

When to seek medical advice

You should contact your doctor as soon as possible if you:

  • have a constant high temperature that lasts for more than three days
  • cough up mucus streaked with blood
  • develop rapid breathing (more than 30 breaths a minute) or chest pains
  • become drowsy or confused
  • experience shortness of breath or other breathing difficulties

You should also contact your doctor as soon as possible if your child is:

  • under three months of age and has a temperature of 38°C or above
  • between three and six months of age and has a temperature of 39°C or above
  • over two years of age and their symptoms persist for more than three days

You should also see your doctor if you have any of the risk factors that make you more vulnerable to developing a pneumococcal infection.

Read about

causes of pneumococcal infections
for more information about these risk factors.

When to seek emergency medical advice

The most serious type of pneumococcal infection is bacterial

, which requires immediate admission to hospital for emergency treatment.

Bacterial meningitis has a number of early warning signs that can occur earlier than the other symptoms.

These are:

  • pain in the muscles, joints or limbs, such as in the legs or hands
  • shivering or unusually cold hands and feet
  • blue lips and pale or blotchy skin

As the condition gets worse it may cause:

  • drowsiness
  • confusion
  • seizures or fits
  • an inability to tolerate bright lights, known as photophobia (less common in young children)
  • a stiff neck (also less common in young children)
  • a rapid breathing rate
  • a blotchy, red rash that does not fade or change colour when you place a glass against it

The symptoms of bacterial meningitis are different in babies and young children. Possible symptoms include:

  • becoming floppy and unresponsive or stiff with jerky movements
  • becoming irritable and not wanting to be held
  • unusual crying

You should immediately request an ambulance if you suspect that you or someone you know has bacterial meningitis.

Causes of pneumococcal infections

Pneumococcal infections are caused by bacteria called **Streptococcus pneumoniae (S. pneumoniae).

Streptococcus pneumoniae

There are more than 90 different strains of S. pneumoniae and some are much more likely to cause serious infection (virulent) than others.

Some strains can be easily killed by infection-fighting white blood cells, while others are resistant and likely to cause a more serious infection.

It is thought that between eight and 10 strains are responsible for two-thirds of cases of serious infections in adults, and most cases in children.

How the bacteria is spread

S. pneumoniae enter the human body through the nose and mouth, and an infection can be spread in the same way as a

or [the flu. This can be through:

  • direct contact, for example, when someone sneezes or coughs, tiny droplets of fluid that contain the bacteria are launched into the air and can be breathed in by others
  • indirect contact, for example, if infected droplets of fluid are transferred from someone's hand to a door handle, someone else who touches the handle may become infected with the bacteria if they then touch their mouth or nose

It is important to emphasise that pneumococcal infections are far less contagious than a cold or flu. This is because most people's immune systems are able to kill the bacteria before they have the opportunity to cause an infection.

Outbreaks of pneumococcal infections can sometimes occur in environments where there are many people who have poorly functioning immune systems, such as in children's nurseries, care homes for the elderly and shelters for people who are homeless.

Risk factors

People with a weakened immune system, either due to their age or general health, are particularly at risk of developing a pneumococcal infection.

The bacteria can move from their throat to other parts of their body, such as the lungs, the blood or the brain. If this occurs, a more serious infection can develop.

People at higher risk include:

  • children under two years of age
  • adults over 65 years of age
  • those with a weakened immune system as a result of a health condition such as
    HIV or AIDS
  • those who are receiving medical treatment that is known to weaken the immune system, such as
    or [corticosteroids]
  • those with a history of spleen disease or dysfunction (the spleen is an organ that filters the blood and plays an important role in fighting infection)
  • those with a chronic respiratory disease, such as
    chronic obstructive pulmonary disease (COPD)
  • those with
    coronary heart disease
    or who have previously had a
    heart attack
  • those with
    chronic kidney disease
    or [chronic liver disease
  • those with
    who need to take insulin
  • those who wear a type of hearing aid called a cochlear implant – people who use these have a slightly increased risk of developing meningitis, but the reasons for this are unclear
  • those who are addicted to alcohol or regularly
    misuse alcohol
    – alcohol misuse is known to weaken the immune system
  • those who are currently infected by the influenza virus – this applies to both seasonal flu and
    swine flu
  • those who smoke cigarettes or other tobacco products
  • those who are living in poverty – many of the factors related to poverty, such as poor diet and living in unhygienic and overcrowded environments, increase a person's risk of developing a pneumococcal infection
  • those with spinal damage that has caused their cerebrospinal fluid (a fluid that surrounds the brain and spine) to leak

Diagnosing pneumococcal infections

Several different tests can be used to diagnose pneumococcal infections. The tests you have will depend on your symptoms.

Some of the tests used are outlined below.

Physical examination

If a pneumococcal infection is suspected, your doctor will listen to your chest with a stethoscope. The fluids produced during an invasive pneumococcal infection often cause a distinctive crackling sound.

Blood test

You may have a

blood test
to check for the presence of bacteria. A high number of infection-fighting white blood cells may indicate the presence of an infection. The blood sample can be sent to a laboratory so the bacteria that caused the infection can be identified.


Several different types of imaging tests may be used depending on your symptoms.

may be able to highlight the presence of fluid in the lung, which would indicate a lung infection. An X-ray uses radiation to produce images of the inside of the body.

Other imaging tests that may be used to investigate a potential pneumococcal infection include:

Blood pressure test

You may have a blood pressure test as a serious infection can often lead to a decrease in blood pressure.

Lumbar puncture test


lumbar puncture
test involves taking a sample of cerebrospinal fluid (the fluid that surrounds the brain and spine) from the base of your spine and checking it for the presence of bacteria. If the sample contains infection-fighting white blood cells and/or bacteria, it may indicate you have meningitis.

Urinary antigen test

A urinary antigen test is a relatively new type of test used to help diagnose a pneumococcal infection.

It involves taking a urine sample and then carrying out a technique known as an immunochromatographic assay. This is able to detect the distinctive protein molecules that make up the outer shell of the S. pneumoniae bacteria.

Treating pneumococcal infections

The treatment you receive depends on whether you have an invasive or non-invasive pneumococcal infection. Antibiotics are often used to treat a serious infection.

Non-invasive pneumococcal infections

Non-invasive pneumococcal infections, such as sinusitis or bronchitis, will usually clear up within a week without the need for treatment.

Drinking plenty of fluids, getting plenty of rest and taking over-the-counter painkillers, such as

, should help relieve your symptoms.

Read more information about treatment for specific types of pneumococcal infections:

Invasive pneumococcal infections

If you have an invasive pneumococcal infection, such as pneumonia, a decision will be made about whether you are well enough to be treated at home or need to be admitted to hospital.

Most doctors use a scoring system, known as the CRB-65 score, to assess the potential seriousness of a case of pneumonia.

  • C stands for confusion: if you are mentally confused you may have a more serious infection.
  • R stands for respiratory rate: your respiratory rate is how many breaths you take in a minute. More than 30 breaths a minute may be a sign your lungs are not working properly.
  • B stands for blood pressure: low blood pressure can be a sign of a more serious infection.
  • 65 indicates whether you are 65 years of age or over: older people are more vulnerable to the effects of infection.

Each of the above criteria is given a score of either 0 or 1 depending on whether or not it is applicable. This scoring system is explained below.

  • A CRB-65 score of 0 means you have a low risk of complications and can usually be treated at home.
  • A CRB-65 score of 1-2 means you have a medium risk of developing complications and you should have a same-day assessment by an expert in treating pneumonia. Depending on the results of the assessment, you may be treated at home or may need to be admitted to hospital.
  • A CRB-65 score of 3 or more means you have a high risk of developing complications and you should be admitted to hospital for urgent treatment.

Hospital admission is also recommended for:

  • any type of invasive pneumococcal infection that has developed in a baby or child younger than two years of age
  • all cases of suspected

Treatment at home

If you are being treated at home, you will usually be prescribed a seven-day course of

. An antibiotic called amoxicillin is the preferred choice. If you are allergic to amoxicillin, alternative antibiotics such as doxycycline can be used.

The most common side effects of the antibiotics used to treat pneumonia are:

These side effects are usually mild.

Sometimes, doxycycline can make your skin more sensitive to the effects of sunlight. Therefore, you should minimise your exposure to direct sunlight and avoid using sun lamps and sun beds when taking doxycycline.

It is very important to finish your course of antibiotics, even if you start to feel better. Not completing the full course of antibiotics could cause the pneumonia to return.

Treatment at hospital

If your symptoms are moderate, you can usually be treated with antibiotic tablets.

If your symptoms are severe, you will usually be given antibiotics through a drip into your arm. You may also be given fluids to stop you becoming dehydrated, and oxygen to help you breathe.

Depending on how well you respond to treatment, it may be possible to switch from a drip to antibiotic tablets after a few days.

Most people who are treated in hospital require a seven to ten-day course of antibiotics. The length of time it will take before you are well enough to return home will depend on your general state of health and whether you experience a more serious type of pneumococcal infection, such as meningitis.


It is usually recommended that you attend a follow-up examination six weeks after the start of your symptoms. This is to check the infection has not caused any serious or permanent damage to the affected parts of your body, such as your lungs.

The follow-up examination usually involves taking a chest

so the state of your lungs can be assessed.

Preventing pneumococcal infections

You can help prevent the spread of a pneumococcal infection by taking some simple hygiene precautions.

These include:

  • washing your hands regularly and thoroughly, particularly after touching your mouth and nose and before handling food
  • coughing and sneezing into a tissue, throwing it away immediately and washing your hands
  • not sharing cups or kitchen utensils with others

Pneumococcal vaccination

Pneumococcal vaccination - also known as the 'pneumo jab' is very effective at preventing pneumococcal infections.

There are two types of pneumococcal vaccination - one for children, known as the pneumococcal conjugate vaccine (PCV) and one for adults, known as pneumococcal polysaccharide vaccine (PPV).


All children are offered pneumococcal vaccination as part of their NHS childhood immunisation schedule.

It involves three injections - at two, four and 13-13 months old.

The pneumococcal vaccination for children is entirely safe, although about one child in 10 will experience some redness and swelling at the site of the injection and symptoms of a mild fever. However, these side effects will pass quickly.

Speak to your doctor or health visitor if you are not sure whether your child has received their pneumococcal vaccination.


Adults can have the pneumococcal vaccine or 'pneumo' jab on the NHS if they are in a high-risk group for developing a pneumococcal infection. Find out more about who should have the pneumococcal vaccine.

If you are eligible, your doctor surgery will contact you to arrange a vaccination. If they do not, contact your doctor to arrange an appointment.

Healthy adults usually only need one dose of the pneumo jab. However, if you have a weakened immune system or spleen disorder may need additional booster doses. Your doctor will be able to advise you about this.

After you've had the pneumo jab you may experience some pain and inflammation at the site of the injection. This should only last for one to three days. Less commonly, some people report the symptoms of a mild fever. Again, this should pass quickly.

Read more information about side effects of the pneumococcal vaccine.


There is an increasing body of evidence that suggests that people who drink an excessive amount of alcohol are at a greater risk of developing invasive pneumococcal infections.

Alcohol is known to suppress the immune system, the body's natural defence system that will attempt to prevent an invasive pneumococcal infection.

Therefore, the best way to lower your risk of developing a pneumococcal infection is to ensure that you stick to the recommended daily amounts of alcohol.

For men, the recommended daily amount of alcohol consumption is three to four units, and for women it is two to three units. A unit of alcohol is equal to about half a pint of normal-strength lager, a small glass of wine or a pub measure (25ml) of spirits.

Speak to your doctor if you are finding it difficult to moderate your alcohol consumption. Counselling and medication are available for people with an alcohol misuse problem.


Smoking is the single biggest risk factor for developing an invasive pneumococcal infection in otherwise healthy adults.

Research has found that almost 60% of previously healthy people who develop an invasive pneumococcal infection are smokers.

It is not known exactly why smoking makes a person more vulnerable to an invasive pneumococcal infection. One theory is that the chemicals contained in tobacco smoke disrupt the normal workings of the immune system and make it less efficient.

As well as reducing your risk of developing an invasive pneumococcal infection, giving up smoking will help reduce your risk of developing other serious health conditions, such as cancer, heart disease and stroke.

If you want to give up smoking, a good first step is to see your doctor. They will be able to provide help and advice about quitting.

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.