Class Code 5951
Serum, Antitoxin Or Virus Mfg
Class Code 5951 applies to California employers engaged in the manufacture of serum, antitoxins, and virus products. These operations carry specialized biological and chemical hazards that affect workers' comp exposure and compliance. The September 1, 2026 approved pure premium rate for this class is $0.482 per $100 of payroll.
What Class Code 5951 Covers
This classification covers production and direct manufacturing operations that produce sera, antitoxins or virus material at commercial scale. Typical covered activities include upstream cell culture or animal inoculation for virus propagation, serum collection and fractionation, antitoxin concentration and purification, viral inactivation or attenuation, aseptic fill-finish and packaging, lyophilization and cold-chain handling, and production-line quality control directly tied to those processes. It also covers technicians and operators who work in controlled environments (biosafety cabinets, clean rooms) and run production fermenters, bioreactors, centrifuges, chromatography systems, or sterile filling equipment. Administrative staff, clerical staff and unrelated contractors are generally coded differently unless they perform hands-on manufacturing tasks that expose them to the same hazards.
Who It Applies To
- Vaccine and biologics manufacturing facilities producing viral products
- Producers of antitoxins and therapeutic sera using animal or human-derived materials
- Contract manufacturing organizations (CMOs) doing fill-finish or bulk virus/serum processing
- Production technicians, aseptic operators, and bioprocess engineers on the manufacturing floor
- Quality control staff performing in-process testing directly in production areas
- Maintenance personnel assigned to production equipment who routinely enter sterile/containment zones
Common Job Duties
- Operating bioreactors, incubators and cell culture systems for viral propagation
- Collecting and fractionating serum or concentrating antitoxin preparations
- Purification steps such as chromatography, ultrafiltration, and centrifugation
- Aseptic filling, stopper placement, capping and labeling in clean rooms
- Inactivation, stabilization and lyophilization of viral or serum products
- Sterilization, cleaning and preventive maintenance of production equipment
- On‑line sampling and quality control assays performed in production suites
Common Injury Risks
Understanding the $0.482 Rate
The pure premium rate of $0.482 per $100 of payroll represents the estimated cost of expected claims for this classification before carrier expense loads and other adjustments. Insurers use that pure premium as the foundation for your policy premium, then apply your experience modification, policy fees, state assessments, and any schedule credits or debits. Final premium is affected by payroll accuracy, proper classification splits (e.g., separating clerical payroll), your loss history (E-Mod), and implemented safety and medical surveillance programs.
Cal/OSHA Compliance Requirements
Manufacturers in this class must comply with Cal/OSHA requirements that commonly apply to biological production: the Bloodborne Pathogens standard (Section 5193) for potential exposure to infectious agents, Hazard Communication (Section 5194) for chemicals and inactivating agents, Respiratory Protection (Section 5144) when inhalation hazards exist, and the Injury and Illness Prevention Program (Section 3203) general duty to provide a written safety program. Employers are expected to implement engineering controls (biosafety cabinets, closed systems), medical surveillance and vaccination where appropriate, PPE, training, and written exposure control plans and records.
How Key HR Helps Employers Under Class Code 5951
A PEO like Key HR can centralize workers' comp administration, provide industry-specific loss control programs, and help document compliance with Cal/OSHA standards. Key HR can assist with job hazard analyses, training programs (bloodborne pathogens, respirators, clean-room procedures), post-injury management and coordinated return-to-work plans, and negotiate workers' comp placements that reflect true operations to avoid misclassification.
Get a QuoteFrequently Asked Questions
Does class code 5951 include research or diagnostic laboratories?
No — 5951 is intended for commercial manufacturing operations that produce sera, antitoxins or virus products. Research, diagnostic or clinical labs that perform bench research or testing are typically classified differently. Ask Key HR or your insurer to confirm classification if your operation mixes production and research activities.
What controls most reduce workers' comp exposure for these operations?
Engineering controls (closed transfer systems, biosafety cabinets, local exhaust ventilation), strict aseptic techniques, comprehensive PPE and respiratory protection programs, vaccination and medical surveillance, and formal procedures for sharps handling and spill response are the most effective measures to reduce claims and lower your experience modification.
How should payroll be recorded when some staff are clerical and others are on the production floor?
Payroll must be allocated to the correct class codes: production floor staff who handle product and enter containment zones belong under 5951, while office/clerical employees should be coded as clerical. Maintenance and sanitation workers who enter production areas may require separate classification. Accurate payroll splits are essential because clerical payroll is charged at much lower rates.
Quick Facts
- Class Code
- 5951
- Classification
- Serum, Antitoxin Or Virus Mfg
- Pure Premium Rate
- $0.482 / $100 payroll
- Effective Date
- September 1, 2026
- Source
- WCIRB Approved Filing
Manage Workers' Comp Through a PEO
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