Smallpox: residual antibody after vaccination.

Area of Science:

• Virology
• Immunology
• Public Health

Background:

• Poxviruses, particularly Orthopoxvirus, pose significant bioterrorism threats due to their rapid environmental spread.
• Smallpox vaccination was discontinued globally in 1980, raising questions about long-term immunity.
• Assessing persistent vaccinia virus antibody levels is crucial for understanding protection against potential smallpox re-emergence.

Purpose of the Study:

• To evaluate the persistence of vaccinia virus antibodies in adults vaccinated during childhood.
• To determine the correlation between vaccination history and antibody presence.
• To compare enzyme immunoassay (EIA) with serum neutralization (SN) for antibody detection.

Main Methods:

• Sera from 204 adults vaccinated as children were analyzed using enzyme immunoassay (EIA).
• Vaccination history (once or more) was recorded.
• EIA results were compared with serum neutralization (SN) for a subset of samples; 56 unvaccinated individuals were also tested.

Main Results:

• Antibody positivity was 67.9% in those vaccinated once and 79.5% in those vaccinated multiple times.
• Only 7.1% of unvaccinated individuals under 30 showed detectable antibodies.
• One serum negative by EIA was positive by SN, indicating potential limitations of EIA alone.

Conclusions:

• Vaccinia virus antibody levels appear to decrease significantly over time following childhood vaccination.
• The findings suggest waning immunity may necessitate booster vaccinations for bioterrorism preparedness.
• Further research is needed to establish correlates of protection and optimal vaccination strategies.