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 by HPS and the Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory (SHLMPRL) and data from SPIDER informs the epidemiology of IPD in Scotland.

 

Surveillance update for January to March 2020

One hundred and forty-eight cases of IPD were reported in the first quarter of 2020. This is lower than the number of cases reported for the corresponding period in the previous four years, which ranged from 205 to 226, as shown in Figure 1.   

Figure 1 is a line graph showing the cumulative number of invasive pneumococcal disease cases reported to SPIDER per week by year. Each line represents a different year from 2016 to the end of the first quarter of 2020. Across all years there is a steady increase in the cumulative number of cases per week. The graph shows that case numbers are lower than for the equivalent period in the previous four years.

Figure 2 includes data on cases reported in the first quarter of 2020 and indicates that IPD continues to occur more frequently in older age groups:

  • 76, or 51.4%, were 65 years and older
  • 56, or 37.8%, were 35 to 64 years old
  • 7, or 4.7%, were aged 15 to 34 years old
  • one, or 0.7%, was aged 5 to 14 years old
  • eight, or 5.4%, were under five years old, of whom three were aged under one year

Figure 2 is a line graph showing the number of invasive pneumococcal disease cases reported to SPIDER per quarter by year from 1999 to the end of the first quarter of 2020. Each line on the graph represents number of cases for each age group. The graph shows the majority of cases were observed in those aged 35 years and over, and the lowest number was observed in the 5 to 14 age group. There is high variability in case numbers by quarter, particularly for those aged 35 years and over.

IPD in children under five years old

Of the 148 IPD cases reported between January and March 2020, eight were in children under five years of age and eligible for PCV13 vaccination. This is lower than the number of cases reported in this age group for the corresponding period in the previous four years, which ranged from 11 to 19. Serotypes detected in children aged under five years in the first quarter of 2020 are shown in Table 1.

Table 1: S. pneumoniae serotypes in paediatric IPD cases reported to SPIDER in 2019
Serotype Less than or equal to 2 months 3 to 11 months 1 year 2 years 3 years 4 years Total under 5 years
Not known 0 0 1 0 1 0 2
PNE9N 0 0 0 0 0 1 1
PNE15B 0 0 1 0 0 0 1
PNE23B 0 0 0 0 0 1 1
PNE27 0 1 0 0 0 0 1
PNE33F 0 1 0 0 0 0 1
PNE35F 0 1 0 0 0 0 1
Total 0 3 2 0 1 2 8

 

Enhanced surveillance questionnaires were returned for six of the eight cases aged under five years. Septicaemia was the most common clinical presentation. Other presentations were pneumonia and pleural empyema.

Of the six cases for whom enhanced surveillance questionnaires were returned:

  • two, or 33.3%, were known to have an underlying risk factor
  • four, or 66.7%, are known to have been discharged alive
  • one, or 16.7%, case was not yet discharged when the form was completed
  • one, or 16.7%, case is known to have died

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 121 of the 148 (81.8%) cases reported in the first quarter of 2020.

The most common serotypes reported were:

  • 8 (31 cases)
  • 3 (14 cases)
  • 9N (12 cases)
  • 22F (8 cases)

A total of 25 cases (16.9%) were caused by serotypes included in PCV13 vaccine, all of whom were aged five years or older.

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 usually only 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 was initially offered as three doses; primary doses at eight and 16 weeks of age, followed by a booster at 12 to 13 months. From April 2020, the PCV13 schedule changed to a primary dose at 12 weeks followed by a booster dose at between 12 and 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

PCV13 uptake statistics are published by Public Health Scotland Data and Intelligence.