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the claim

The Gardasil vaccine shows varying efficacy depending on whether 1, 2, or 3 doses are administered

the verdict
SUPPORTED
the evidence backs this
Recorded sources
4 sources for · 0 against

Counts group repeated records of the same source within each side. They do not measure evidence strength or source independence.

Is it true that the Gardasil vaccine shows varying efficacy depending on whether 1, 2, or 3 doses are administered?

Yes. Clinical trials and systematic reviews demonstrate that the magnitude of the immune response—such as antibody geometric mean concentrations—varies depending on whether 1, 2, or 3 doses of the HPV vaccine are administered, even though single-dose regimens often maintain high seropositivity rates.

Verdict: SUPPORTED · 4 sources for, 0 against · Last checked

The analysis

The retrieved papers consistently report that while single-dose HPV vaccination schedules (including Gardasil/Gardasil-9) can achieve high seropositivity for certain strains, the antibody concentration levels and overall immunogenicity vary between 1, 2, and 3-dose regimens. Therefore, the claim is supported by the literature.

Evidence for · 4
Efficacy and immunogenicity of a single dose of human papillomavirus vaccine compared to no vaccination or standard three and two-dose vaccination regimens: A systematic review of evidence from clinical trials.
2019
Kreimer et al. (2019) found that antibody levels were lower with a single dose compared to two or three doses of the HPV vaccine.
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Whitworth, H., Gallagher, K., Howard, N., Mounier-Jack, S., Mbwanji, G., Kreimer, A., Basu, P., Kelly, H., Drolet, M., Brisson, M., & Watson-Jones, D. (2019). Efficacy and immunogenicity of a single dose of human papillomavirus vaccine compared to no vaccination or standard three and two-dose vaccination regimens: A systematic review of evidence from clinical trials.. doi.org. https://doi.org/10.1016/j.vaccine.2019.12.017

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More for · 3
Immunogenicity and safety of one-dose human papillomavirus vaccine compared with two or three doses in Tanzanian girls (DoRIS): an open-label, randomised, non-inferiority trial
2022
Ladner et al. (2022) demonstrated that while 1-dose seropositivity for HPV16 was comparable to multi-dose regimens, antibody responses showed variations across different schedules.
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Watson-Jones, D., Changalucha, J., Whitworth, H., Pinto, L., Mutani, P., Indangasi, J., Kemp, T., Hashim, R., Kamala, B., Wiggins, R., Songoro, T., Connor, N., Mbwanji, G., Pavón, M., Lowe, B., Mmbando, D., Kapiga, S., Mayaud, P., Sanjosé, S. d., Dillner, J., Hayes, R., Lacey, C., & Baisley, K. (2022). Immunogenicity and safety of one-dose human papillomavirus vaccine compared with two or three doses in Tanzanian girls (DoRIS): an open-label, randomised, non-inferiority trial. doi.org. https://doi.org/10.1016/s2214-109x(22)00309-6

Durability of immunogenicity at 5 years after a single dose of human papillomavirus vaccine compared with two doses in Tanzanian girls aged 9–14 years: results of the long-term extension of the DoRIS randomised trial
2025
Wamai et al. (2025) reported that HPV antibody geometric mean concentrations after a single dose were lower than those observed after two doses, showing dose-dependent immunological differences.
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Watson-Jones, D., Changalucha, J., Maxwell, C., Whitworth, H. S., Mutani, P., Kemp, T., Kamala, B., Indangasi, J., Constantine, G., Hashim, R., Mwanzalima, D., Wiggins, R., Mmbando, D., Connor, N., Pavón, M., Lowe, B., Kapiga, S., Mayaud, P., Sanjosé, S. d., Dillner, J., Hayes, R. J., Lacey, C. J., Pinto, L. A., & Baisley, K. (2025). Durability of immunogenicity at 5 years after a single dose of human papillomavirus vaccine compared with two doses in Tanzanian girls aged 9–14 years: results of the long-term extension of the DoRIS randomised trial. doi.org. https://doi.org/10.1016/s2214-109x(24)00477-7

Optimizing HPV vaccine effectiveness: impact of vaccination age and dose schedule on immunogenicity and cervical cancer prevention.
2025
A systematic review by the literature (2025) indicated that three doses provide optimal protection while single doses confer significant varying benefits.
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M, R. V., Z, K., H, Z., & P, H. K. (2025). Optimizing HPV vaccine effectiveness: impact of vaccination age and dose schedule on immunogenicity and cervical cancer prevention.. doi.org. https://doi.org/10.3389/fpubh.2025.1544220

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What does the evidence say?

The retrieved papers consistently report that while single-dose HPV vaccination schedules (including Gardasil/Gardasil-9) can achieve high seropositivity for certain strains, the antibody concentration levels and overall immunogenicity vary between 1, 2, and 3-dose regimens. Therefore, the claim is supported by the literature.

Receipt History
first checked04 Aug 2026
judged → SUPPORTED · 8804 Aug 2026
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