Pap Smear Guide in Singapore: Your Complete Guide to Cervical Health 2025

When was the last time you thought about your cervical health?

For many women, it rarely crosses the mind, especially when there are no symptoms. Life gets busy, appointments get delayed, and screening often slips to the bottom of the list. Yet cervical cancer doesn’t wait. It develops quietly, often without warning, and by the time symptoms appear, it may already be advanced.

In Singapore, cervical cancer remains one of the top ten cancers affecting women [1]. But it is also one of the most preventable. The key lies in early detection — and that begins with a simple, routine test: the Pap smear.

Despite widespread availability and decades of medical evidence supporting its effectiveness, screening rates in Singapore are still not where they should be. Some women are unsure when to start or how often to go. Others feel anxious or embarrassed, or don’t know what the procedure involves. This lack of awareness and confidence can lead to delays in diagnosis and missed opportunities for early treatment.

This guide is here to change that. Whether you are 25 and preparing for your first test, or 45 and unsure if you are overdue, this article offers a clear and practical overview of Pap smears in Singapore. We will explain what the test is, why it matters, who needs it, how often it’s recommended, and where you can get it done. 

Understanding Pap Smears

Cervical cancer screening can feel unfamiliar or even intimidating, especially if it’s your first time. But understanding what a Pap smear is and how it works is the first step toward making confident, informed choices about your health. Here is what the test involves and how it compares with another common screening method: the HPV test.

What is a Pap smear?

A Pap smear is a screening test used to detect abnormal changes in the cells of the cervix [2]. These changes, if left untreated, can develop into cervical cancer over time. During the test, a healthcare provider uses a small brush or spatula to gently collect cells from the cervix. The sample is then sent to a laboratory for examination under a microscope.

The main goal of a Pap smear is to find early warning signs — cellular changes that aren’t yet cancer, but could become cancer if not managed. Detecting these abnormalities early allows for simple and effective treatment, long before cancer has a chance to develop.

The procedure is quick, typically taking less than five minutes. It may feel slightly uncomfortable, but it should not be painful, and no recovery time is needed afterward.

Pap Smear vs HPV Test — What’s the Difference?

While both the Pap smear and HPV test are used in cervical cancer screening, they test for different things and are recommended at different stages of life. Understanding the distinction helps clarify which test you need and why.

Aspect	Pap Smear	HPV Test
What it checks for	Abnormal or precancerous cells on the cervix	Presence of high-risk HPV strains that can cause cervical cancer
Purpose	Detects early cellular changes	Detects the virus that causes those cellular changes
Recommended age group	Women aged 25–29	Women aged 30–69
Screening interval	Every 3 years	Every 5 years
Used for	Early detection of abnormal cells	Identifying high-risk HPV before cell changes occur
Can it be done together?	Sometimes recommended as a co-test depending on history	Yes, often combined with Pap smear in women over 30

Both tests play a role in safeguarding cervical health. Your doctor will recommend the appropriate test based on your age, screening history, and overall risk profile.

Cervical Cancer in Singapore

Cervical cancer remains a serious yet largely preventable health concern for women. The availability of screening and vaccination has significantly improved early detection, but the burden of the disease persists — particularly when regular screening is delayed or skipped. In Singapore, the patterns of diagnosis and the factors that increase risk highlight the ongoing need for awareness and timely intervention.

Prevalence and Statistics

According to the Singapore Cancer Registry, cervical cancer ranks among the top ten most common cancers in women [3]. Each year, around 200 women are diagnosed, and approximately 70 lose their lives to the disease [4]. Although the incidence has declined over the decades—thanks to improved access to Pap smears and the introduction of HPV vaccination—the rates are still concerning, particularly among women who do not undergo regular screening.

Data shows that the risk of cervical cancer increases with age, and many of the cases diagnosed are in women who have either never been screened or have not had a Pap smear in the last five years. This underlines the importance of consistent follow-up, especially in women aged 30 and above.

Risk factors

Several well-established factors can increase a woman’s risk of developing cervical cancer. Understanding these risks is key to recognising the importance of regular screening:

• Persistent HPV infection — the most significant risk factor. High-risk strains of the human papillomavirus (especially HPV 16 and 18) are responsible for the majority of cervical cancer cases [5].

• Smoking — chemicals in tobacco can damage cervical cells, making them more susceptible to HPV-related changes [6].

• Early sexual activity or multiple sexual partners — these factors increase the likelihood of HPV exposure.

• Weakened immune system — conditions like HIV [7] or long-term use of immunosuppressive medication can reduce the body’s ability to fight HPV infections.

• Lack of regular screening — women who have never had a Pap smear or have infrequent screenings face a significantly higher risk of late-stage diagnosis.

• Long-term use of oral contraceptives — some studies suggest a slightly increased risk after five or more years of continuous use [8].

While not all risk factors can be controlled, regular screening and HPV vaccination remain the most effective tools for prevention and early detection of cervical cancer.

National Guidelines for Cervical Cancer Screening

Cervical cancer screening is not a one-size-fits-all process. In Singapore, national guidelines are tailored to maximise the benefits of screening while minimising unnecessary procedures. The Ministry of Health has established age-based recommendations to ensure that women receive the most suitable test at the appropriate time.

Understanding these guidelines can help you stay on track with your screenings, avoid confusion about when to start or stop, and ensure you’re receiving the most relevant care for your age and risk profile. Here are the recommended screening ages and intervals [9]. 

Women aged 25 to 29

Cervical screening is recommended for women based on their age, and sexual history:

• Women aged 25 years old, and above who have ever had sexual intercourse should begin regular cervical cancer screening at 25 years old.
• Women who have never had sexual intercourse do not require cervical screening. However, if they experience symptoms such as abnormal vaginal bleeding, then they should consult a doctor

Additionally, this group of women is encouraged to undergo a routine pap smear every 3 years. At this age, Pap smears are preferred over HPV tests because younger women are more likely to clear HPV infections naturally, and over-testing may lead to unnecessary interventions.

Women aged 30 to 69

Women between the ages of 30 to 69 should undergo an HPV test every 5 years if the result is negative. The HPV test is more accurate in detecting high-risk HPV strains, and is now the primary screening tool for women in this age group. It can identify risk earlier, even before any visible cellular changes occur.

Women in both age groups should ensure that their screenings are up to date, even if they have no symptoms and feel well. Regular screening is preventive, not reactive—it’s meant to catch changes before they cause harm.

Women who have had HPV Vaccination

Women who have received the HPV vaccine should continue to follow the same screening schedule as those who are unvaccinated.

Immunocompromised women

Women with weakened immune systems, including those on long-term immunosuppressive therapy, may require more frequent screening. These cases should be assessed, and managed individually by a gynaecologist.

Special Considerations

Women over 69

Women in this age group may stop screening if they have had two consecutive negative HPV tests in the last 10 years, with the most recent test within the past 5 years. Those with a history of abnormal results may still require continued monitoring.

Meanwhile, women with a history of treatment for CIN 2, CIN 3, or adenocarcinoma in situ (AIS) should continue routine screening for at least 20 years, even if this extends beyond the age of 69 years old.

Women who have had a hysterectomy

The need for continued cervical screening depends on the type of hysterectomy, and the woman’s medical history. This includes:

Total hysterectomy for benign conditions

Further cervical cancer screening is only needed if:

• The woman has a history of normal cervical cytology.
• Histopathology confirms the cervix was benign with no precancerous or cancerous changes.

Subtotal (partial) hysterectomy

Cervical screening should continue according to the national screening guidelines, as the cervix remains in place.

Hysterectomy where cervical histology is unknown

For women in this group, a baseline vaginal vault smear is recommended. However, if the result is normal, then no further screening is necessary.

Histology of cervical intraepithelial neoplasia (CIN)

If the excision margins were involved or not adequately assessed, follow-up should be guided by a gyneacologist. In general, vault smears should be taken at least annually.

Additionally, if CIN (Cin 1/2/3) was completely excised at the time of hysterectomy:

• Vault smears should be done annually for 5 years.
• Then, every 2 years for an additional period as advised by the clinician.

Preparing for a Pap Smear

Feeling uncertain before a Pap smear is completely normal, especially if it’s your first time. Knowing how to prepare can help ease any anxiety, ensure the most accurate results, and make the experience as smooth as possible.

Optimal Timing

The best time to schedule a Pap smear is about 10 to 20 days after the first day of your periods, when you are not menstruating. While it is still possible to perform the test during light bleeding, heavy menstrual flow may interfere with the accuracy of the cell sample. If your cycle is unpredictable, let the clinic know in advance so they can advise on the best timing.

Before the Test: What to Avoid

To ensure the best quality sample, it’s recommended to avoid the following 24 to 48 hours before your appointment:

• Sexual intercourse — seminal fluid and friction can temporarily affect cervical cells and obscure results.

• Douching or vaginal washes —these can disrupt the natural environment of the cervix and wash away or alter the cells that need to be examined.

• Tampons, vaginal creams, suppositories, or lubricants — these products can interfere with sample collection and analysis.

If you are unsure whether your recent activities could affect your results, speak with your healthcare provider before the test. It’s also perfectly acceptable to ask questions during the appointment or request a female provider if that makes you more comfortable.

Being well-prepared not only helps your doctor perform the test efficiently but also increases the likelihood of a clear and conclusive result — avoiding the need for a repeat test.

The Pap Smear Procedure

Understanding what happens during a Pap smear can help reduce uncertainty and make the experience more manageable. The test itself is quick and usually takes only a few minutes. While it may feel unfamiliar or slightly uncomfortable, it is not typically painful — and your doctor will guide you through each step. 

What to Expect During the Test

You will begin by lying on an examination table, typically with your knees bent and feet placed in stirrups. A device called a speculum is gently inserted into the vagina to hold it open, allowing the doctor to clearly view the cervix.

Using a small, soft brush or spatula, the doctor will collect a sample of cells from the surface of your cervix. This may cause a slight scraping sensation or mild pressure, but it usually lasts only a few seconds. Once the sample is collected, the speculum is removed and the procedure is complete.

The entire process takes less than five minutes.

Is It Painful?

Most women describe the test as mildly uncomfortable rather than painful. Some may feel pressure or cramping similar to menstrual discomfort, especially if it’s their first time or if they are feeling tense. Taking slow, deep breaths and trying to stay relaxed can help ease any discomfort during the exam.

If you experience significant pain at any point, let your doctor know immediately, as it could indicate an underlying issue that may need further attention.

Being informed and knowing what to expect can make the experience much less stressful. If you have concerns or specific preferences — such as having a female doctor or being talked through the process in advance — don’t hesitate to request this when making your appointment.

Interpreting Pap Smear Results and What Happens Next

Once your Pap smear is complete, the collected sample is sent to a laboratory for analysis. Results are usually available within one to two weeks and will be shared with you by your doctor.

Pap smear results typically fall into one of three categories:

• Normal (negative) — this means no abnormal cells were found, and you can continue routine screening as advised based on your age.

• Abnormal — this indicates that some changes were detected in the cervical cells. It does not mean you have cancer, but further testing may be needed to determine the cause and whether treatment is necessary.

• Unsatisfactory — in some cases, the sample may not contain enough cells or may be obscured by blood or mucus. Your doctor may recommend repeating the test to ensure a clear reading.

If your result is abnormal, the next steps depend on the type and severity of the changes. Your doctor may recommend:

• A repeat Pap smear after a short interval
• An HPV test to check for high-risk viral strains
• A colposcopy, a procedure that allows the cervix to be examined more closely under magnification
• A biopsy (if further investigation is needed)
  

Timely follow-up is essential, even if you feel well. Many cervical cell changes cause no symptoms but can progress silently over time. 

Cervical Cancer Screening in Singapore

Cost and convenience should never stand in the way of essential healthcare. While many women assume that cervical cancer screening is expensive or hard to access, the reality is quite the opposite — Pap smears and HPV tests are widely available across Singapore, often at highly subsidised rates.

For those seeking more personalised care, many private women’s clinics and GP practices offer Pap smears as part of health screening packages. At Ardennes Health, we provide discreet, comfortable, and professionally guided Pap smear screening in a calm, patient-centred setting. Whether you are coming in for your first test or a routine follow-up, our team is here to ensure you feel informed, supported, and cared for at every step.

With accessible options across both public and private sectors, there’s no reason to postpone your screening. What matters most is staying on schedule — because early detection saves lives.

Taking Charge of Your Cervical Health

Cervical cancer is one of the few cancers that can be prevented through early detection and timely treatment — and the Pap smear remains one of the most effective tools in achieving that. Yet, many women continue to miss out on screening due to uncertainty, discomfort, or the misconception that it’s unnecessary in the absence of symptoms.

Pap smear is a quick, safe, and reliable test that can detect changes in cervical cells long before they pose a serious threat. When combined with regular HPV testing and follow-up care, it offers women a powerful layer of protection against a disease that often develops without warning.

If you are due for a Pap smear or simply unsure where to begin, schedule a consultation with us for confidential, professional care tailored to your needs.

References 

1. Cervical cancer. Retrieved May 6, 2025, from https://www.singaporecancersociety.org.sg/learn-about-cancer/types-of-cancer/cervical-cancer.html 
2. What is a pap test? Cleveland Clinic. Retrieved May 6, 2025, from https://my.clevelandclinic.org/health/diagnostics/4267-pap-smear 
3. Singapore cancer society. Retrieved May 6, 2025, from https://singaporecancersociety.org.sg/index.php 
4. Cervical Cancer – What It Is. SingHealth. Retrieved May 6, 2025, from https://www.singhealth.com.sg/patient-care/conditions-treatments/cervical-cancer 
5. Okunade, K. S. (2020). Human papillomavirus and cervical cancer. Journal of Obstetrics and Gynaecology: The Journal of the Institute of Obstetrics and Gynaecology, 40(5), 602–608. https://doi.org/10.1080/01443615.2019.1634030 
6. Smoking and cervical cancer. Australian Government Department of Health and Aged Care. Retrieved May 6, 2025, from https://www.health.gov.au/our-work/tobaccofacts/smoking-and-cervical-cancer#:~:text=Chemicals%20from%20smoke%20change%20your,cells%20of%20women%20who%20smoke. 
7. Hewavisenti, R. V., Arena, J., Ahlenstiel, C. L., & Sasson, S. C. (2023). Human papillomavirus in the setting of immunodeficiency: Pathogenesis and the emergence of next-generation therapies to reduce the high associated cancer risk. Frontiers in Immunology, 14, 1112513. https://doi.org/10.3389/fimmu.2023.1112513 
8. Oral contraceptives (Birth control pills) and cancer risk—Nci. (2018, March 1). [cgvArticle]. https://www.cancer.gov/about-cancer/causes-prevention/risk/hormones/oral-contraceptives-fact-sheet 
9. Why annual pap smears are history – but routine ob-gyn visits are not. (n.d.). Retrieved May 6, 2025, from https://www.acog.org/womens-health/experts-and-stories/the-latest/why-annual-pap-smears-are-history-but-routine-ob-gyn-visits-are-not 
10. Enhanced screen for life(Sfl). Ministry of Health. Retrieved May 6, 2025, from https://www.moh.gov.sg/managing-expenses/schemes-and-subsidies/enhanced-screen-for-life/ 

Influenza, more commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. In Singapore, the flu is fairly common, given the hot and humid weather all-year-round, creating a conducive environment for viruses to survive and circulate easily. 

Flu vaccinations remain the most effective way to prevent influenza and its complications. It not only reduces the likelihood of falling ill but also limits the severity of symptoms if infection occurs. Moreover, getting vaccinated helps reduce the spread of the virus in the community as it protects those who are unable to receive the vaccine, such as very young infants or individuals with specific medical conditions. In this article, we’ll look into flu vaccinations in Singapore, who needs them, and why. 

Understanding the Flu: Spread and Symptoms

Influenza is an acute viral infection caused by influenza viruses, which primarily affect the respiratory system. There are four main types of influenza viruses, A, B, C, and D, but only types A and B are responsible for seasonal flu outbreaks in humans [4]. These viruses are highly infectious and have the ability to mutate rapidly, resulting in new strains that can vary from year to year.

Influenza spreads mainly through droplets expelled when an infected person coughs, sneezes, or talks. These droplets can land in the mouths or noses of nearby individuals or be inhaled into the lungs. The virus can also spread through contact with contaminated surfaces, such as door handles or shared devices, followed by touching the face. Because it can be transmitted before symptoms appear and up to a week after falling ill, influenza is particularly difficult to contain without proactive measures like vaccination and good hygiene practices.

Potential complications of influenza include:

• Pneumonia — a serious lung infection that can be life-threatening, especially in the elderly and those with chronic illnesses.

• Sinus and ear infections — particularly in children.

• Exacerbation of chronic conditions — such as asthma, diabetes, and heart disease.

• Hospitalisation or death — in severe cases, particularly among vulnerable populations.

Why is the flu so common in Singapore?

The flu is relatively common in Singapore for the following reasons:

• Tropical climate — Because of Singapore’s constant warm and humid climate, influenza viruses can circulate all-year-round. 

• High population density — Singapore is a densely populated urban society, which increases chances of person-to-person transmission.

• International travel hub — The country is well-known for being an international travel hub, increasing risk of imported flu strains.

• Enclosed environments — Enclosed, air-conditioned spaces are common in Singapore, and are conducive spaces for virus survival and transmission.

Who Should Consider a Flu Vaccine?

Influenza vaccination is recommended for everyone aged 6 months and older, with rare exceptions. The Ministry of Health (MOH) in Singapore [5], along with global health authorities such as the World Health Organization (WHO) [6], advises annual flu vaccination as a key preventive measure. This is because influenza viruses evolve constantly, and the vaccine is updated regularly to offer protection against the most common circulating strains.

While the general population can benefit from vaccination, certain groups face a significantly higher risk of developing serious complications from the flu. For these individuals, the flu vaccine is not only a preventive measure, it can be life-saving.

Elderly Individuals (65 years and Above)

Older adults are more vulnerable to severe flu-related illnesses [7]. With age, the immune system weakens, which minimises the body’s ability to fight infections effectively. Influenza in the elderly is more likely to lead to hospitalisation, pneumonia, and, in some cases, death. Annual vaccination offers critical protection by reducing the severity of illness and the risk of complications.

Young Children (6 months to Under 5 Years)

Young children, particularly those under five years of age, have less developed immune systems, which makes them more susceptible to influenza and its complications, including febrile seizures and respiratory infections [8]. The flu vaccine helps to strengthen their immunity and reduce transmission in childcare settings and homes.

Pregnant Women

Pregnant women are more prone to severe flu symptoms and complications, especially in the later stages of pregnancy [9]. Importantly, the flu vaccine also provides protection to the unborn child, with antibodies passed from mother to baby. Vaccination is safe during any trimester and is strongly recommended as part of routine maternal care.

Individuals with Chronic Medical Conditions

People living with chronic conditions such as diabetes, asthma, chronic lung disease, heart disease, or compromised immune systems are more likely to experience complications from the flu [10]. Influenza can exacerbate existing conditions and lead to longer recovery times. Annual vaccination helps lower these risks and prevents disease flare-ups triggered by flu infection.

Healthcare Workers and Caregivers

Those who work in healthcare or provide care to vulnerable individuals, such as the elderly or chronically ill, are at increased risk of contracting and spreading influenza. Vaccinating this group not only protects them but also helps safeguard the health of the people they care for.

When’s the best time to get a flu vaccination?

There is no hard-and-fast rule when it comes to getting a flu vaccine. However, there are certain instances where it may be more beneficial for you, such as:

• Peaks in flu circulation — In Singapore, ideal times to get a flu vaccine would be in April, to protect against the mid-year spike, and October to protect you until the end of the year, when flu more commonly spreads. 

• Before traveling — Getting a flu vaccination right before a trip can help prevent you from falling ill and putting a halt on your holiday. 

• Before the school term starts — Schools are high-risk environments for flu transmission, and getting your child vaccinated ensures a good start to their school term, protecting them from infection.

• Before medical procedures — If you expect to be hospitalised or have a compromised immunity, getting a flu vaccination will be ideal for extra protection and optimal outcomes while you heal from your procedure. 

Addressing Common Misconceptions

Despite widespread public health campaigns and scientific evidence, several misconceptions about the flu vaccine persist. These misunderstandings can discourage people from getting vaccinated; as a result, they may put themselves and others at risk. Here are some common myths associated with influenza vaccines.

“The Flu Vaccine Can Cause The Flu”

This is one of the most persistent myths. In reality, the flu vaccine used in Singapore contains inactivated (killed) viruses or fragments of the virus that cannot cause illness. These components are designed to trigger an immune response, which helps the body build protection without causing infection.

Some people may experience mild side effects after vaccination, such as a low-grade fever, fatigue, or soreness at the injection site, but these are signs that the immune system is responding to the vaccine, not symptoms of influenza. The flu vaccine cannot give you the flu.

“Healthy Individuals Don’t Need the Vaccine”

It’s a common belief that flu vaccination is only necessary for the elderly or people with chronic illnesses. While high-risk groups are more likely to experience severe complications, healthy individuals can still get infected and suffer from uncomfortable symptoms, time off work or school, and, in rare cases, complications like pneumonia.

Moreover, healthy individuals can transmit the virus to others, including family members or colleagues who may be more vulnerable. Vaccinating healthy people contributes to community protection and helps break the chain of transmission.

“Vaccination Is Unnecessary If It’s Not Flu Season”

Unlike temperate countries with clear flu seasons, Singapore experiences influenza activity throughout the year, with peaks typically seen from May to July and November to January. This makes it important to stay protected regardless of the time of year.

Waiting for a “flu season” in Singapore can lead to missed opportunities for prevention. As immunity builds about two weeks after vaccination, timely vaccination, before known peak periods or ahead of travel to countries experiencing seasonal outbreaks, is essential for effective protection.

Potential Side Effects and Safety

The flu vaccine has a strong safety track record and is generally well-tolerated. Still, knowing what to expect can help you feel more confident about your decision.

Common Side Effects

Most people experience no issues after their flu shot. If side effects do occur, they are usually mild and go away within a couple of days. These may include:

• A sore or slightly swollen area around the injection site
• Low-grade fever
• Mild fatigue or muscle aches

These are normal immune responses and a sign that your body is developing protection.

Rare Side Effects

Severe reactions to the flu vaccine are extremely rare. In isolated cases, people may have allergic responses, such as hives, swelling, or breathing difficulties, usually within minutes of the injection.

Our clinical team monitors every patient briefly after vaccination and is fully equipped to manage any adverse reaction safely and promptly.

Why Flu Vaccination Matters Now More Than Ever

At Ardennes Health, we offer seasonal influenza vaccinations as part of our commitment to preventive care for individuals and families.

Influenza continues to be a significant public health concern in Singapore, as it affects people across all age groups. With year-round flu activity and seasonal surges, the importance of annual vaccination cannot be overstated. The flu vaccine offers reliable protection — not only reducing your risk of falling ill but also helping to prevent severe complications, hospitalisations, and the spread of the virus to others. 

If you are unsure about whether the flu vaccine is right for you, our medical team is here to provide clear, personalised guidance based on your health needs. Book an appointment (link to contact us page) with us today for a consultation. 

References 

1. Flu measures. (22nd April 2008.). Ministry of Health. Retrieved April 7, 2025, from https://www.moh.gov.sg/newsroom/flu-measures/ 
2. Drobnik, J., Pobrotyn, P., Witczak, I. T., Antczak, A., & Susło, R. (2021). Influenza as an important factor causing increased risk of patients’ deaths, excessive morbidity and prolonged hospital stays. Archives of Medical Science : AMS, 19(4), 941–951. https://doi.org/10.5114/aoms/138145 
3. Influenza vaccination services offered by community pharmacists under new sandbox initiative. (n.d.). Ministry of Health. Retrieved April 7, 2025, from https://www.moh.gov.sg/newsroom/influenza-vaccination-services-offered-by-community-pharmacists-under-new-sandbox-initiative/ 
4. CDC. (2024, September 27). Types of influenza viruses. Influenza (Flu). https://www.cdc.gov/flu/about/viruses-types.html 
5. Protocols and enhanced screening measures to prevent cross-border spread of influenza into singapore. (6th March 2025). Ministry of Health. Retrieved April 7, 2025, from https://www.moh.gov.sg/newsroom/protocols-and-enhanced-screening-measures-to-prevent-cross-border-spread-of-influenza-into-singapore/ 
6. Strengthening influenza vaccination policies and programmes. (n.d.). Retrieved April 7, 2025, from https://www.who.int/news/item/04-02-2025-strengthening-influenza-vaccination-policies-and-programmes 
7. Flu and older adults. (2022, June 14). National Institute on Aging. https://www.nia.nih.gov/health/flu/flu-and-older-adults 
8. CDC. (2024, September 26). Respiratory viruses and young children. Respiratory Illnesses. https://www.cdc.gov/respiratory-viruses/risk-factors/young-children.html 
9. Oseghale, O., Vlahos, R., O’Leary, J. J., Brooks, R. D., Brooks, D. A., Liong, S., & Selemidis, S. (2022). Influenza virus infection during pregnancy as a trigger of acute and chronic complications. Viruses, 14(12), 2729. https://doi.org/10.3390/v14122729 
10. American Lung Association. Flu symptoms and risk factors. Retrieved April 7, 2025, from https://www.lung.org/lung-health-diseases/lung-disease-lookup/influenza/symptoms-causes-and-risk 
11. Kim, T. H. (2014). Seasonal influenza and vaccine herd effect. Clinical and Experimental Vaccine Research, 3(2), 128–132. https://doi.org/10.7774/cevr.2014.3.2.128