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HPV Vaccination and Pap Smears
Cervical cancer is one of the cancers for which early intervention may help reduce risk. Combining HPV vaccination, which helps protect against infection with certain types of the virus, with regular screening methods such as Pap smears and HPV testing provides a multi-layered approach to prevention. This strategy may help detect cellular changes early, before they can progress to cancer. Consulting a gynaecologist ensures that your screening and vaccination intervals are aligned with current national clinical guidelines and are tailored to your individual health profile.
How HPV Causes Cervical Cancer
Cervical cancer typically begins when high-risk strains of HPV infect the deep layers of the cervical lining through microscopic abrasions. While the immune system naturally clears most infections, a persistent presence of the virus can lead to abnormal cell development. Persistent high-risk HPV infection can trigger a cascade of cellular changes:
- CIN 1 (Low-grade dysplasia): Mild abnormalities affecting the lower third of the cervical epithelium. Many cases resolve naturally within 1-2 years.
- CIN 2 (Moderate dysplasia): Abnormal cells extend to the middle third of the epithelium. Regression is less likely than in CIN 1.
- CIN 3 (Severe dysplasia/Carcinoma in situ): Abnormal cells are present throughout the epithelium but have not invaded underlying tissue. Without treatment, some cases may progress to invasive cancer.
Pre-cancerous changes can be detected and treated before they progress to invasive cancer.
HPV Vaccination
Vaccine Types Available
Two HPV vaccines are approved for use in Singapore. Each targets different combinations of HPV types.
| HPV2 vaccine | HPV9 vaccine | |
|---|---|---|
| Suitable for HPV types | 16, 18 | 6, 11, 16, 18, 31, 33, 45, 52, 58 |
| Indications |
|
Prevention of the following cancers caused by HPV types 16, 18, 31, 33, 45, 52 and 58:
|
| Age |
|
Females and males aged 9 to 45, or as advised by your doctor. |
| Schedule | Females aged 9 to 14 – Two doses, 5 to 13 months apart Females aged 15 to 25 – Three doses
|
Females and males aged 9 to 14 – Two doses, between 5 to 13 months apart Females and males aged 15 to 45 – Three doses Second dose: To be taken 2 months after the first dose Third doses: To be taken 4 months after the second dose |
Recommended Age and Schedule
HPV vaccination is typically recommended during early adolescence, when the body usually mounts a stronger immune response. Vaccination before potential exposure to HPV may help establish protection against the targeted virus types. The vaccination programme consists of either two or three doses, depending on the age at which the series is started. The doses are administered over several months. While vaccination is generally advised at a younger age, individuals who may have already been exposed to some HPV types can still receive the vaccine if appropriate.
Vaccination After Sexual Activity
Having had sexual activity does not prevent you from receiving the HPV vaccine. Even if you have already been exposed to one HPV type, the vaccine provides coverage against the other types included in the formulation. However, the vaccine does not treat existing infections or cellular changes; it is intended to help protect against new infections with the targeted HPV types.
? Did You Know? HPV vaccines use non-infectious, virus-like particles to stimulate an immune response. As the vaccines do not cover all high-risk HPV types, regular cervical screening remains important for ongoing protection and early detection.
Cervical Cancer Screening Methods
Pap Smear (Cervical Cytology)
A Pap smear is a screening method for detecting cervical cell changes before they develop into cancer. During the procedure, a speculum is gently inserted to allow visualisation of the cervix. Cells are then collected from the transformation zone, the area where columnar cells meet squamous cells and where most cervical cancers originate. Pap smear results are reported using the Bethesda System:
| Negative for Intraepithelial Lesion or Malignancy (NILM) | Normal result |
| Atypical Squamous Cells of Undetermined Significance Atypical Squamous Cells of Undetermined Significance | Minor cellular changes that may require HPV testing or repeat Pap smear |
| Low-grade Squamous Intraepithelial Lesion LSIL | Mild dysplasia (abnormal cell growth), often from a transient HPV infection |
| High-grade Squamous Intraepithelial Lesion HSIL | Moderate to severe dysplasia requiring colposcopy (a procedure using a magnifying instrument to closely examine the cervix) |
| Atypical Squamous Cells, cannot exclude HSIL ASC-H | Requires colposcopy for further evaluation |
A Pap smear is a screening tool, not a diagnostic test. Abnormal results do not always indicate cancer. They show that some cells appear different from normal, and further investigation is needed to determine whether treatment is required.
HPV Testing
HPV testing is a screening method that detects the presence of high-risk HPV DNA or RNA, which is the virus’s genetic material, in cervical cells. It is generally more sensitive than Pap smears for identifying CIN 2 or higher-grade lesions. However, many women who test positive for high-risk HPV will never develop significant cellular changes. HPV testing can be performed:
- As a primary screening test
- Alongside a Pap smear as a co-test
- As a reflex test when Pap results show ASC-US
Singapore Screening Guidelines
Screening recommendations vary by age: Ages 25–29 Women who have ever been sexually active are advised to have a Pap smear every 3 years. This remains the primary screening method for this age group. Ages 30–69 You may choose either:
- An HPV test alone every 5 years, or
- HPV + Pap smear (co-test) every 5 years
From age 30 onwards, HPV testing is recommended as the primary screening method.
- After age 69: Routine screening may stop if past results have been consistently normal and there are no added risk factors. Your doctor will guide this based on your health history.
- After a total hysterectomy: Screening is usually no longer needed if the procedure was done for non-cancerous reasons and there’s no history of significant cervical cell changes (CIN 2 or higher).
If there is a history of pre-cancer or cancer, continued monitoring may still be advised.
HPV Vaccination (Singapore)
The Singapore National Childhood Immunisation Schedule (NCIS) and National Adult Immunisation Schedule (NAIS) recommend that all females aged 9 to 26 receive the HPV vaccine.
- Ages below 15: 2 doses
- Ages 15 and above: 3 doses (given at 0, 1–2 months, and 6 months)
While not routinely included for males under these national schedules, some HPV vaccines are approved for use in males to help protect against infection and reduce transmission of the virus.
⚠️ Important Note HPV vaccination does not remove the need for cervical screening. The vaccine does not cover all high-risk HPV types, and some women may have been exposed to HPV before vaccination. Vaccinated women should continue screening according to standard guidelines.
Understanding Your Results
Normal Results
A normal Pap smear (NILM) with negative HPV testing indicates low risk of cervical abnormalities. Routine screening intervals can be followed.
Abnormal Pap, HPV Negative
ASC-US with negative HPV testing suggests that any cellular changes are unlikely to be HPV-related. Standard practice is usually to return to routine screening, as the risk of underlying disease is minimal.
Abnormal Pap, HPV Positive
This combination warrants closer evaluation. The specific follow-up depends on the degree of Pap abnormality:
- ASC-US or LSIL with HPV positive: Colposcopy or repeat testing in 12 months
- HSIL or ASC-H: Colposcopy is typically recommended, regardless of HPV status
HPV Positive, Normal Pap
Persistent high-risk HPV with normal cytology can occur because HPV infection may precede cellular changes. Management options include repeat co-testing in 12 months or colposcopy, depending on whether HPV 16 or 18 is detected.
Colposcopy and Treatment
Colposcopy and related procedures are used to examine the cervix more closely and, if necessary, remove abnormal cells. These procedures carry a small risk of complications, such as post-operative bleeding or a potential impact on future pregnancies (cervical insufficiency). Your gynaecologist will discuss the procedure, potential risks, and considerations with you before treatment.
Cervical Dysplasia (CIN) and Management
| Condition | Management |
|---|---|
| CIN 1 (Low-Grade) | With observation and repeat testing at 12 months, as most cases resolve spontaneously. |
| CIN 2 (Moderate-Grade) | Treatment or continued observation, particularly for younger women who wish to preserve fertility, since spontaneous regression can occur. |
| CIN 3 (High-Grade) | Management usually involves treatment due to the possibility of progression. |
Your gynaecologist will discuss possible approaches and considerations with you.
Treatment Options
- LLETZ/LEEP (Large Loop Excision of the Transformation Zone): A wire loop with electrical current is used to remove the abnormal area. This procedure is commonly performed and is usually done under local anaesthesia.
- Cold Knife Conisation: A cone-shaped section of the cervix is removed. This procedure is used when LLETZ is insufficient or when invasion cannot be excluded.
- Cryotherapy: Abnormal cells are frozen to destroy them. This is less commonly used now because tissue for pathological examination may not be obtainable.
These procedures carry a small risk of complications, such as post-operative bleeding or a potential impact on future pregnancies. Your gynaecologist will explain the procedure, potential risks, and considerations before treatment.
Factors That May Affect Your Screening Schedule
Some individuals may require closer monitoring or screening at shorter intervals based on their medical history or health status.
- Immunocompromised status (a weakened immune system): HIV infection, organ transplantation, or immunosuppressive therapy may increase the likelihood of persistent HPV infection and cervical cell changes. More frequent screening may be advised.
- Previous high-grade abnormality: Women who have previously been treated for CIN 2 or CIN 3 may require follow-up screening at shorter intervals for a period of time.
- Incomplete previous screening: Women who have never been screened or who have long gaps between screenings may wish to discuss an appropriate screening plan with their gynaecologist.
Next Steps to Consider
- HPV vaccination: If you have not been vaccinated, you may wish to discuss HPV vaccination with your gynaecologist. The 9-valent vaccine covers several HPV types associated with cervical disease.
- Cervical screening: Arrange cervical screening according to your age group and national screening recommendations. This may include a Pap smear or HPV test.
- Track your results: Keeping records of screening dates and results can help with follow-up planning and continuity of care if you change healthcare providers.
- Attend all follow-up appointments: If screening results show abnormalities, follow-up tests or assessments may be advised.
- Discuss your individual risk factors: Share relevant medical history with your gynaecologist, including immunocompromised status, previous abnormal results, or incomplete screening history.
When to Consult a Gynaecologist
- Abnormal vaginal bleeding, such as between periods, after intercourse, or post-menopause
- Persistent unusual vaginal discharge
- Pelvic pain without a clear cause
- Overdue for cervical screening
- Questions about HPV vaccination eligibility
- Previous abnormal screening results requiring follow-up
- New diagnosis affecting immune function
Commonly Asked Questions
Can I still develop cervical cancer if I have been vaccinated?
HPV vaccination does not protect against all high-risk HPV types associated with cervical cancer. In addition, some women may have been exposed to HPV before vaccination. For this reason, regular cervical screening remains important for all women, including those who have received the HPV vaccine.
Is the HPV vaccine safe?
HPV vaccines do not contain live viruses, so they cannot cause HPV infection. Common side effects include pain, redness or swelling at the injection site, mild fever, or headache, which usually resolve on their own. Rare allergic reactions can occur; seek medical attention if you notice swelling of the face, lips, or tongue, difficulty breathing, or widespread rashes.
How accurate are Pap smears?
Pap smears can sometimes miss abnormalities or detect changes that are not serious. Regular screening is important, and HPV testing may be used alongside or instead of Pap smears to help detect changes earlier, as recommended.
Should my male partner get the HPV vaccine?
HPV vaccination is recommended for males as well. It can protect against genital warts and certain HPV-related cancers, and may reduce HPV transmission to female partners.
Next Steps
Check your HPV vaccination status and be aware of your recommended cervical screening schedule based on your age. Review any previous abnormal results that may need follow-up.
If you are due for cervical cancer screening or experiencing abnormal vaginal bleeding, consult a gynaecologist to determine appropriate screening intervals and vaccination eligibility.
