Extract: Revaccination with standard calf lymph vaccine was performed on 26 children who had received a primary vaccination with an attenuated smallpox vaccine, CVI-78, and 22 children who had received primary vaccination with standard calf lymph. Revaccination resulted in a vesicular reaction in 96% of those who had been vaccinated previously with CVI-78 and 73% of those vaccinated previously with standard calf lymph. All children had a positive hemagglutination-inhibition (HI) antibody titer either after primary vaccination or revaccination. Only 65% of those initially vaccinated with CVI-78 vaccine had positive neutralizing antibodies after revaccination. All children who received primary vaccination with standard calf lymph had postrevaccination neutralizing antibodies. The children who had neither a dermal nor a serologic response after primary vaccination responded as primary vaccinees on challenge with standard calf lymph.
Speculation: Vaccination with CVI-78 alone offers only partial protection against variola and revaccination with standard calf lymph is necessary to offer full protection. The incomplete neutralizing antibody response in the CVI-78 group after revaccination with standard vaccine may indicate, however, that revaccination protection in this group is incomplete. Vaccination with CVI-78 also is not completely protective against the complications that could result from primary standard calf lymph vaccination since a significant percentage of those who received primary vaccination with CVI-78 had no postvaccination serologic or dermal response and responded like primary vaccinees when challenged with standard vaccine.
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Speers, W., Wesley, R., Neff, J. et al. Evaluation of Two Kinds of Smallpox Vaccine: CVI-78 and Calf Lymph Vaccine: II. Clinical and Serologic Observations of Response to Revaccination with Calf Lymph Vaccine. Pediatr Res 9, 628–632 (1975). https://doi.org/10.1203/00006450-197508000-00003
- vaccine, calf lymph
- vaccinia virus