Evidence of immune memory 8.5 years following administration of a prophylactic human papillomavirus type 16 vaccine.
BACKGROUND
The duration of protection conferred by prophylactic human papillomavirus (HPV) L1 virus-like particle vaccines is a critical determinant of their public health impact. A feature of vaccines that confer long-term immunity is their ability to induce immune memory.


OBJECTIVE
We evaluated antibody responses against HPV types 6, 11, 16 and 18 following administration of the quadrivalent HPV-6/11/16/18 vaccine to women who had previously received a monovalent HPV-16 vaccine.


METHODS
As part of an extended follow-up study conducted between 2006 and 2009 in Seattle, Washington, we administered the quadrivalent HPV-6/11/16/18 vaccine to 52 women (19 vaccine and 33 placebo recipients) who had participated in a monovalent HPV-16 vaccine trial 8.5 years earlier. Serum samples were tested for anti-HPV antibodies using competitive Luminex immunoassay.


RESULTS
Following administration of the first dose of the quadrivalent HPV-6/11/16/18 vaccine, the anti-HPV-16 geometric mean titer among monovalent HPV-16 vaccine recipients (GMT=5024.0 milli-Merck units per milliliter [mMU/mL]; 95% confidence interval [CI]: 2710.1, 9313.6 mMU/mL) substantially exceeded that among the placebo recipients (GMT=136.1; 95% CI: 78.5, 235.8 mMU/mL; p<0.01) and their own highest anti-HPV-16 response observed during the original trial (GMT at month 7 of the original trial=1552.7 mMU/mL; 95% CI: 1072.6, 2247.7 mMU/mL; p<0.01).


CONCLUSIONS
The findings suggest that the administration of the three-dose regimen of the monovalent HPV-16 vaccine had produced memory lymphocytes, characterized by a heightened immune response following administration of the quadrivalent HPV-6/11/16/18 vaccine that effectively served as an antigen challenge.
Department of Epidemiology, University of Washington, Seattle, WA, USA. ali.x.rowhani-rahbar@kp.org
Ali
A
Rowhani-Rahbar
Frances B
FB
Alvarez
Janine T
JT
Bryan
James P
JP
Hughes
Stephen E
SE
Hawes
Noel S
NS
Weiss
Laura A
LA
Koutsky
D000328:Adult; D052685:Alphapapillomavirus / Q000276:immunology; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology*; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18; D052162:Human papillomavirus 16 / Q000276:immunology*; D006801:Humans; D007118:Immunoassay; D007156:Immunologic Memory / Q000276:immunology; D030361:Papillomavirus Infections / Q000517:prevention & control*; D053918:Papillomavirus Vaccines / Q000008:administration & dosage* / Q000276:immunology; D002583:Uterine Cervical Neoplasms / Q000276:immunology / Q000517:prevention & control*
D000914:Antibodies, Viral; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18; D053918:Papillomavirus Vaccines