Handling infectious viruses in pharma labs

The Covid-19 pandemic has changed how the world now looks at viruses. Pharmaceutical laboratories have, however, been dealing with unusual diseases for a while. ROWAN WATT-PRINGLE explores protocols and best practice for protecting workers in these settings.

The US Department of Labor’s Occupational Safety and Health Administration (OSHA) lists four types of measures for protecting pharmaceutical laboratory staff handling unusual viruses sent for analysis. As well as key regulations regarding quality control, personnel training, and current Good Manufacturing Practice (cGMP), OSHA’s guidelines are an excellent starting point for establishing comprehensive laboratory risk-management programmes and control strategies.

OSHA notes that most laboratories employ a combination of engineering controls, administrative controls, work practices and personal protective equipment (PPE). Here, we take a look at what each of these measures involves.

Engineering Controls

As permanent changes to the work environment that “reduce exposure to hazards and do not rely on worker behavior”, engineering controls provide the most effective protection. They may include ISO room classifications, as well as the use of microbiological safety cabinets (MSCs) and other systems like heating, ventilation and air-conditioning.

One recommendation for equipment usage is to replace all glassware with plasticware, while the UK Government Health and Safety Executive (UKHSE) highlights the need for care when using equipment like centrifuges, which can “create considerable health risks by liquid spillage and droplet dispersion”. According to the World Health Organization (WHO), meanwhile, laboratories conducting propagative work including virus culture, isolation or neutralisation assays should be fitted with inward directional airflow at Biosafety Level 3.

Pharmaceutical cleanroom and PPE supplier Lindström Group notes the importance of facility design. Design aspects include proper maintenance of humidity, temperature and air filtration; compliance with regulatory standards; and the presence of air-locks, restricted access barrier systems, or laminar flow to help eliminate contaminants in high-risk areas.

Failsafe protocols reduce the risk of airborne viruses escaping; UKHSE recommends primary containment using different classes of MSCs depending on the virus hazard level, and “secondary containment using appropriate ventilation” for all airborne infectious pathogens causing severe human disease.

Administrative Controls

Modifying staff work schedules and tasks can minimise exposure to workplace hazards. This usually entails the development of various work plans and standard operating procedures, including local contingency plans for potential emergency scenarios.

The WHO notes that certain experimental procedures “may carry additional risks of virus mutations with possible increased pathogenicity and/or transmissibility.” The organisation recommends specific risk assessments and reduction measures before culturing viruses in the presence of antiviral drugs, co-infecting cell cultures with different viruses or deliberately modifying virus genetics.

Work Practices

Regular staff training is essential and may include viral analysis protocols, cGMP guidelines, disinfection procedures, and working with high-risk equipment, amongst others.

Disinfection protocols, for example, vary between different viruses. The WHO cites appropriate disinfectants with proven activity against enveloped viruses including hypochlorite (bleach), alcohol, hydrogen peroxide, quaternary ammonium compounds and phenolic compounds. They emphasise the need to “ensure the disinfectant is efficacious against the pathogen being handled” and disinfect infectious waste long enough to ensure complete inactivation. Laboratories may also require further measures like microbial filtered disinfectants or hydrogen peroxide vapour generators for bio-decontamination.

Personal Protective Equipment

Examples of PPE include respirators, eye protection, solid-front or wrap-around gowns, and disposable gloves. The appropriate PPE will depend on various factors, including whether a virus is airborne. OSHA notes that PPE should be properly fitted and worn; regularly maintained and replaced; and properly removed and disinfected (or disposed of) to avoid contamination.

According to the US Centers for Disease Control, training and practice on the use of PPE are critical elements in safe laboratory operations. It recommends using a PPE checklist, concluding that PPE should be carefully selected to provide the appropriate level of protection without compromising staff health or their ability to perform their duties safely.