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 April to June 2019

Figure 1 presents cumulative IPD cases between 2015 and the second quarter of 2019. During weeks 14 to 26 of 2019, 116 cases of IPD were reported to SPIDER, bringing the total number of cases for the first two quarters of 2019 to 339. This is comparable to the number of cases for the same period in the previous three years, which ranged from 338 to 410.

Figure 1 is a line graph showing the cumulative (week 14 to 26) number of invasive pneumococcal disease cases reported to SPIDER per week by year. Each line represents a different year from 2015 to the second quarter of 2019. Across all years there is a steady increase in the cumulative number of cases per week. The graph shows that case numbers are slightly lower than for the same period in 2016 and 2017, and similar to the equivalent period in 2018.

Figure 2 includes data on cases reported between April and June 2019 and indicates that IPD continues to occur more frequently in older age groups:

  • 55 (47.4%) were 65 years and older
  • 41 (35.3%) were 35 to 64 years old
  • 15 (12.9%) were 15 to 34 years old
  • Five (4.3%) were under five years old, of whom four 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 second quarter of 2019 and 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 IPD cases reported between April and June 2019, five were in children under five years of age and eligible for PCV13 vaccination. This brings the total number of cases in children under five years reported in the first two quarters of 2019 to 19, which is the same as for the equivalent period in 2018. Serotypes detected in children aged under five years for the second quarter of 2019 are shown in Table 1.

Table 1: S. pneumoniae serotypes in paediatric IPD cases reported to SPIDER in 2019 to week 26
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 1 5 1 0 2 0 9
PNE008 1 0 1 0 0 0 2
PNE10A 0 0 1 0 0 0 1
PNE12F 0 1 0 0 0 0 1
PNE15B 0 0 1 0 0 0 1
PNE19A 0 0 1 0 0 0 1
PNE23B 0 1 0 0 0 0 1
PNE27 1 0 0 0 0 0 1
>PNE33F 1 1 0 0 0 0 2
Total 4 8 5 0 2 0 19

 

Enhanced surveillance questionnaires were returned for 18 of the 19 cases aged under five years reported in the first two quarters of 2019. Septicaemia and pneumonia were the most common presentations. Other presentations included pleural empyema, meningitis, arthritis and septic shock. 

Of the 18 cases for whom enhanced surveillance questionnaires were returned:

  • three (16.6%) were known to have an underlying risk factor
  • 13 (72.2%) are known to have been discharged alive
  • Five (27.8%) cases were not yet discharged when the form was completed

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 278 of the 339 (82.0%) cases reported in the first two quarters of 2019.

The most common serotypes reported were:

  • 8 (78 cases)
  • 9N (23 cases)
  • 12F (21 cases)
  • 19A (18 cases)
  • 3 (16 cases)

A total of 48 cases (14.2%) were caused by serotypes included in PCV13 vaccine, 47 of whom were aged five years or older. There was one PCV13 vaccine serotype case aged under five years. This case was infected with serotype 19A, and had received two doses of PCV13 vaccine.

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.