Table 3.

Common methods for virus inactivation^*

Treatment	Treatment conditions	Advantages	Limitations	Relevant properties to be recorded
Pasteurization	Heat treatment in aqueous solution at 60°C for 10 hr Stabilizers (sugars, amino acids, or acetate) added	Inactivates enveloped and some nonenveloped viruses, including HAV and B19V Relatively simple equipment	Protein stabilizers may also stabilize viruses Stabilizers usually need to be removed after process is completed HBV is relatively heat stable Process validation required	Temperature Temperature homogeneity Duration Stabilizer concentration
Terminal dry heat	Heat treatment of lyophilized product at 80°C for 72 hr or Heat treatment of lyophilized product at 100°C for 30‐120 min	Inactivates enveloped and some nonenveloped viruses, including HAV Treatment applied on final container	At least 80°C usually required for reduction of hepatitis viruses Requires strict control of moisture content Freezing and lyophilization and dry heat treatment conditions require extensive validation	Temperature Temperature homogeneity Duration Moisture content
Vapor heat	Heat treatment of lyophilized product at 60°C for 10 hr, with water content adjusted to 7%‐8% (wt/wt) Additional heating at 80°C for 1 hr for some products	Inactivates enveloped and some nonenveloped viruses, including HAV	Freezing and lyophilization and heating conditions require extensive validation	Temperature Temperature homogeneity Duration Moisture during heating
S/D	Typical conditions: 0.3% TNBP and 1% nonionic detergent, either Tween 80 (≥6 hr) or Triton X‐100 (≥4 hr) at 24°C	Very efficient against enveloped viruses Does not denature proteins High process recovery Relatively simple equipment Not generally affected by buffers	Nonenveloped viruses unaffected S/D reagents must be removed	Temperature Duration Reagent concentration Lipid levels must be controlled In‐process solution free from gross aggregates potentially protecting viruses

* Adapted from the World Health Organization.13

TNBP = tri(n‐butyl)phosphate.