How recently? Are you sure that your immunity is still good? My last immunization was with the drops on the sugar cube in 1961. Hopefully, it was free of contamination from SV40. I'm not so smug in my belief that my 1961 vintage immunization would protect me against a smallpox attack tomorrow. Especially of the viral load was so concentrated that my immune system would have no hope of reacting in time to overcome it.