The Joint Committee on Vaccination and Immunisation (JCVI), produce the Department of Health publication ‘Immunisation against Infectious Disease’ also known as the Green Book. The November 2011 edition advises there appears to be a strong association between welding and the development of pneumococcal disease, particularly lobar pneumonia in welders, and added them to the list of patient groups for whom pneumococcal vaccination (PPV23-purified capsular polysaccharide) can prevent is recommended [1]. HSE has also published advice on this topic [2].

Overview

The Joint Committee on Vaccination and Immunisation (JCVI), produce the Department of Health publication ‘Immunisation against Infectious Disease’ also known as the Green Book. The November 2011 edition advises there appears to be a strong association between welding and the development of pneumococcal disease, particularly lobar pneumonia in welders, and added them to the list of patient groups for whom pneumococcal vaccination  (PPV23-purified capsular polysaccharide) can prevent is recommended [1]. HSE has also published advice on this topic [2].

Population at risk

There is an estimated figure of 60,000 welders in the UK. HSE estimate that in the UK, even with current access to modern control methods, 2 welders die each year from pneumococcal pneumonia and 40-50 others are hospitalised due to the disease. This organism often affects younger as well as older welders. Other occupations with some exposure to metal fume who will also benefit from immunisation, include moulders, coremakers and furnacemen. It is important to note from the research that the risk of pneumonia appears to be confined to exposed men of working age. An added elevation of mortality from pneumonia has been evident in those working with ferrous metal (due to the iron hypothesis- see below)[3].

Research in Birmingham and West Midlands

Among the evidence reviewed to support the opinion of the Joint Committee was the case control study by Palmer et al (2003) of hospital diagnosed pneumonia cases in between 1996 – 99 in Birmingham and the West Midlands [4]. Across 11 hospitals, 525 men aged 20 – 64 had community-acquired pneumonia. The study found:

• Welders had an increased overall rate of pneumonia (adjusted odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.1–2.4) compared with controls non exposed controls
• Higher risks linked to exposure in the past year to ferrous fumes or smoking
• Lobar pneumonia = 3.0, 95% CI = 1.4–6.7)
• A high proportion of confirmed pneumoniae lobar pneumonia cases were welders (OR 3.1 95% CI = 1.0–9.5)

A cohort of 30 427 male Swedish construction workers exposed to metal fume was studied for risks of death from pneumonia.

The increased relative risk of S. pneumonia as the cause was 5.8 compared to other workers [5].

 The pathological process

The bacterium Streptococcus pneumoniae, (pneumococcus) is:

• a common commensal microorganism in the upper respiratory tract in healthy humans
• there are approximately 90 different serotypes
• some cause serious infective illnesses, including pneumonia, septicaemia and meningitis
• these invasive pneumococcal diseases (IPD) carry a significant fatality rate, of approximately 5 – 12% in adults of working age [6,7]

The exact underlying mechanisms leading to infection in welders remains unclear. Some data suggest that chronic exposure to metal fume blunts responsiveness to inhaled particulate matter through free radical injury of host defences against infection [8], alternatively inhaled iron may exceed the capacity of the iron binding protein system of the lungs, causing overgrowth of organisms that thrive on it [5].

Risk assessment and controls

Although the dose–response relationship and the level below which exposures should be controlled have not yet been defined, good control of workplace exposure remains the preferred method of managing the risk to workers. This would include:

• effective local exhaust ventilation,
• appropriate personal protective equipment and
• effective education of workers to minimise exposure
• smoking cessation

The risk of pneumonia is significantly lower for those workers who are minimally exposed to metal fume when using automated laser welding/cutting, or hybrid welding.

The decision to offer the vaccination for pneumococcal pneumonia should be made by employers as an additional protective measure to the combination of fume exposure control measures already in place.

Pneumococcal vaccination

Several vaccines for pneumococcal pneumonia are available worldwide. The vaccine offered to children in the UK, is known as the pneumococcal conjugate vaccine. It prevents infection for seven different serotypes. The vaccine offered to adults, PPV23, contains purified capsular polysaccharide from each of 23 capsular types of pneumococcus.

These 23 account for 96% of the pneumococcal isolates that cause serious infection in the UK.

In addition:

• the vaccine is safe, and most healthy adults develop a good antibody response to a single dose of PPV three weeks after immunization,
• following a single injection, post-immunisation antibody levels usually begin to wane after about 5 years, although the true potential extent of immunity is unclear
• it will not prevent pneumococcal pneumonia arising from the 67 or so serotypes not covered by the vaccine,
• it will not prevent pneumonias caused by other microorganisms, or metal fume pneumonitis.

Whom to vaccinate and when?

Employees who should be offered vaccination with PPV23:

• welders
• moulders,
• coremakers
• furnacemen etc.

Those who will not benefit include those who undertake:

• plastic, electron beam and friction stir welding
• metal laser work
• powder bed deposition
• cold spray technologies etc

Funding

No Department of Health funding is available for PPV23 to be given in welders, so employers should:

• treat their responsibility to vaccinate exposed workers seriously under the Health and safety at Work Act 1974
• fund their vaccination programme,
• expect to pay around £30 per vaccination
• make arrangements for vaccination with a reputable occupational health provider such as MOHS
• recognise that all the other control measures remain necessary.

 What the vaccine will not do

The vaccination does not:

• offer protection against other illnesses caused by welding or metal fume, such as asthma
• guarantee them protection from pneumonia and may have a limited duration of effectiveness

Enforcement

Vaccination is not a regulatory requirement. Enforcement action by HSE will not be taken against employers who have made the decision not to implement a vaccination programme. But this decision must be based on a suitable and sufficient COSHH risk assessment that demonstrates effective control of fume exposure.

Timing of vaccination

There is uncertainty regarding the optimum timing of vaccination and the JCVI has not recommended an age restriction. It can be administered to exposed workers as ‘a one off’, at any age or stage in their career.

Main recommendations:

• Occupational health providers and employers should offer welders and other employees who are exposed to metal fume a single dose of PPV23.
• Workplace controls should be used to minimise exposure to metal fume as far as reasonably possible.
• Exposed workers should be encouraged to discontinue or avoid taking up smoking, to reduce pneumonia, cardiovascular and chronic obstructive pulmonary disease.

References

1. Department of Health. Immunisation against Infectious Disease, 2006 (updated November 2011), Chapter 25 v2_0, p305.http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/documents/digitalasset/dh_131000.pdf
2. Health and Safety Executive Pneumonia vaccination for employees exposed to welding and metal fume,hse.gov.uk/pubns/eis44.htm.
3. Palmer KT, Poole J, Ayres JG, Mann J, Burge PS, Coggon D. Exposure to metal fume and infectious pneumonia. Am J Epidemiol 2003; 157: 227–233.
4. Palmer KT and Cosgrove MP: Vaccinating welders against pneumonia 329. Downloaded from http://occmed.oxfordjournals.org/ at University of Southampton on July 5, 2012
5. Torén K, Qvarfordt I, Bergdahl IA, Järvholm B. Increased mortality from infectious pneumonia after occupational exposure to inorganic dust, metal fumes and chemicals. Thorax 2011; 66:992–996.
6. Robinson KA, Baughman W, Rothrock G, et al., for the Active Bacterial Core Surveillance (ABCs)/Emerging Infections Program Network. Epidemiology of invasive Streptococcus pneumoniae infections in the United States, 1995–1998. J Am Med Assoc 2001;285:1729–1735
7. Burman LA, Norrby R, Trollfors B. Invasive pneumococcal infections: incidence, predisposing factors, and prognosis. Rev Infect Dis 1985; 2:133–142.
8. Palmer KT, McNeill Love R, Poole JR et al. Inflammatory responses to the occupational inhalation of metal fume. Eur Resp J 2006; 27:366–373.

Dr Jacquie Halliday-Bell, July 2014