Pneumococcal disease

Background

Pneumococcal infections are defined as invasive or non-invasive according to which area of the body is affected. Invasive pneumococcal disease (IPD) is caused by infection of normally sterile sites, for example, blood and cerebrospinal fluid (CSF).

IPD is a major cause of morbidity and mortality, especially amongst:

  • the very young
  • the elderly
  • those with impaired immunity

Non-invasive forms of the infection commonly cause:

  • middle ear infection (otitis media)
  • worsening of bronchitis
  • pneumonia

As with most infectious respiratory diseases, the numbers of cases of pneumococcal infection peak during winter. Up to 50% of people can carry pneumococci in their nose and throat without developing serious infection.

Streptococcus pneumoniae (S. pneumoniae) is the bacterium responsible for causing pneumococcal infection and is characterised by its outer coat, known as capsular polysaccharide. Different capsular types can be distinguished via a process known as serotyping. There are about 90 different types of pneumococci, about a quarter of which cause serious illness.

For public information on pneumococcal disease, visit NHS inform.

Guidance

For all infection prevention and control guidance visit the A-Z ​pathogens section of the National Infection and Prevention Control Manual.

Data and surveillance

Invasive Pneumococcal Disease (IPD) surveillance is based on local and reference laboratory reports confirming isolation of S. pneumoniae from sterile body sites, mainly blood and CSF. In 1999, the Scottish Pneumococcal Invasive Disease Enhanced Reporting (SPIDER) scheme was introduced. The enhanced surveillance scheme is jointly managed with the Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory (SHLMPRL) and data from SPIDER informs the epidemiology of IPD in Scotland.

 

Surveillance update for 2018

Figure 1 presents cumulative IPD cases between 2008 and the fourth quarter of 2018. During weeks 40 to 52 of 2018, 202 cases of IPD were reported to SPIDER, bringing the annual total to 621, the lowest since 2015. Since 2008, total annual IPD cases have ranged from 439 to 713 and each of the last four years represents the highest annual case numbers reported since 2008.

Figure 1 is a line graph showing the cumulative (week 1 to 52) number of invasive pneumococcal disease cases reported to SPIDER per week by year. Each line represents a different year from 2008 to the fourth quarter of 2018. The graph shows that despite case numbers being at their lowest since 2015, annual case numbers between 2015 and 2018 have been at their highest since 2008.

Information on cases reported thus far in 2018 (Figure 2) indicates that IPD continues to occur more frequently in older age groups:

  • 296, which is 47.7%, were 65 years and older
  • 250, which is 40.3%, were 35 to 64 years old
  • 21, which is 3.4%, were 15 to 34 years
  • 11, which is 1.8%, were 5 to 14 years
  • 43, which is 6.9%, were under five years old, of whom 27 of were under the age of two

Figure 2 is a line graph showing the number of invasive pneumococcal disease cases reported to SPIDER per quarter by year. The data ranges from 1999 to the fourth quarter of 2018 and each line on the graph represents number of cases for each age group. high variability in the number of cases per quarter, particularly for those aged 35 and over. The graph shows the majority of cases were observed in the older age groups (aged 35 years and over) and demonstrates high variability in case numbers by quarter for these groups. The lowest number of cases was observed in the 5-14 age group.

IPD in children under five years old

Of the IPD cases reported in 2018, 43 were in children under five years of age and eligible for PCV13 vaccination, which is similar to total cases reported in 2017. From 2010 to 2017, between 26 and 53 cases were reported annually in those aged under five. Serotypes detected in children aged under five years for 2018 are shown in Table 1.

Table 1 shows Streptococcus pneumoniae serotypes identified for cases in those under the age of five and reported during 2018. Data is presented by age group and shows that serotype was known for 26 of the 43 cases (60.5%). Serotype 33F was the most commonly reported (four cases), followed by serotypes 3 and 8 (three cases reported for each type). 31 (72%) of cases were aged two years or under.

Enhanced surveillance questionnaires were returned for 41 of the 43 cases aged under five years reported in 2018:

  • 14, or 32.6%, presented with pneumonia
  • two, or 4.7%, with septicaemia and pneumonia
  • 11, or 25.6%, with septicaemia
  • three, or 7%, with meningitis
  • one, or 2.3%, with meningitis, septicaemia and pneumonia
  • two, or 4.7%, with meningitis and septicaemia
  • six , or 14%, information on clinical presentation was unavailable
  • four, or 9.3%, with ‘other’ presentations including fever, urinary tract infection, respiratory tract infection and appendicitis

Of the 43 cases:

  • 12, or 27.9%, were known to have an underlying risk factor
  • 35, or 81.4%, are known to have been discharged alive
  • one, or 2.3%, case was not yet discharged when the form was completed
  • five, or 111.6%, did not have discharge outcome information available
  • two, or 4.7%, died

There were an additional six cases of IPD in children aged over 5, who were also eligible for vaccination with PCV13. However detailed information is unavailable for these cases as they were not included in the enhanced surveillance programme.

Circulating serotypes of Streptococcus pneumoniae

All IPD isolates and specimens should be sent to the reference laboratory for further typing and antimicrobial sensitivities. Typing results were available for 521 of the 621 cases reported in 2018 (83.9%).

The most common serotypes reported were:

  • 8, with 114 cases
  • 9N , with 48 cases
  • 12F, with 49 cases
  • 3, with 56 cases
  • 22F, with 42 cases

A total of 95 cases (15.3%) were caused by serotypes included in PCV13 vaccine, 88 of whom were aged five years or older. There were seven PCV13 vaccine serotype cases in those aged under five years. Four were infected with serotype 3, one with serotype 19A, one with serotype 19F and one with serotype 7F. Three cases had received three doses of PCV13 vaccine and are thus classified as vaccine failures and three were not yet old enough to receive the PCV13 vaccine. Vaccination status was unavailable for one case.

Surveillance form

Surveillance of invasive pneumococcal disease in children aged under five years (SPIDER)

Vaccination

Two pneumococcal vaccines are available that help to protect against pneumococcal disease.

The pneumococcal polysaccharide vaccine, PPV23, is recommended for many of the same people who receive an annual flu vaccination. Unlike the flu vaccine which is given every year, the pneumococcal vaccine is only usually given once. In 2003, the pneumococcal vaccination for all people aged 65 years and over was introduced, in addition to those aged under 65, with certain underlying conditions. This vaccine offers protection against 23 serotypes of IPD.

In September 2006, the pneumococcal conjugate vaccine PCV7 was introduced into the routine childhood immunisation schedule. In spring 2010, PCV7 was replaced with PCV13 to provide broader protection against more serotypes of S. pneumoniae. PCV13 vaccine follows the same three dose immunisation schedule at eight and 16 weeks of age followed by a booster at 12 to 13 months. PCV13 offers protection against the following 13 serotypes of S. pneumoniae:

  • 1
  • 3
  • 4
  • 5
  • 14
  • 6A
  • 6B
  • 7F
  • 9V
  • 18C
  • 19A
  • 19F
  • 23F 

To coincide with the introduction of PCV7, enhanced surveillance was established for children under five years of age.


Vaccine uptake statistics

Vaccine uptake statistics are available from the Information Services Division (ISD) website.