Background
Human papillomaviruses (HPV) cause several human cancers. Bivalent (Cervarix) and quadrivalent (qGardasil) HPV vaccines both contain virus-like particles of the major oncogenic HPV types 16 and 18, but cross-protect also against some non-vaccine types. However, data on long-term sustainability of the cross-reactive antibody responses to HPV vaccines is scarce.
Methods
Serum samples donated 7-12 years after immunization at age 16-17 with bivalent (N=730) or quadrivalent (N=337) HPV vaccine were retrieved from the population-based Finnish Maternity Cohort biobank. Serum antibody levels against HPV types 6,11,16,18,31,33,35,39,45,51,52,56,58,59,68,73 were determined using multiplex pseudovirion binding assay. Antibody avidity was assessed using ammonium thiocyanate treatment.
Results
Seropositivity for HPV31,33,35,45,51,52,58,59,68,73 was increasingly common (p≤0.001; chi-square test for trend for each one of these types) when women had high anti-HPV16 antibody levels. For eight non-vaccine HPV types seropositivity was more common among recipients of bivalent than quadrivalent vaccine, in particular for HPV31,35,45,51,52,58 (p<0.001). Antibody avidity was higher in the quadrivalent vaccine recipients for HPV6,11 and two of the non-vaccine types, but lower for HPV16 and 18 (p<0.001).
Conclusions
Both vaccines elicit cross-reactive antibodies detectable even twelve years after vaccination. Cross-reactive seropositivity is more common in women with high anti-HPV16 antibody response and in the bivalent vaccine recipients.