AVIDITY AND TITERS OF THE ANTIBODY-RESPONSE TO 2 INACTIVATED POLIOVIRUS VACCINES WITH DIFFERENT ANTIGEN CONTENT

The inactivated poliovirus vaccine is heat stabile, gives high serum I gG concentrations but less pronounced mucosal immunity and must be giv en as repeated injections. A new enhanced-potency Dutch inactivated va ccine could circumvent these difficulties. We compared antibody concen trations measured as neutralization or ELISA titers, and avidity of se rum and salivary antibodies in children vaccinated with three doses of the earlier Swedish vaccine given over nine months or the new antigen -rich vaccine. After three doses, but not after two, serum neutralizat ion titers for type 1 and type 3 poliovirus were higher using the new vaccine but secretory IgA levels in saliva were similar. The avidity o f the serum IgG antibodies was significantly higher after two doses of the new vaccine than after three doses of the old. Thus the new vacci ne gives excellent antibody responses of high titers and avidities, bu t should preferably be given in three doses.