Why Influenza Is a Serious Risk for People with Asthma in Singapore — and What to Do About It

Many people with asthma manage their condition well on most days. Reliever inhalers are on hand, preventer medication is taken as prescribed, and life carries on. But every year, during Singapore’s flu-active periods, many asthma patients find themselves in a GP clinic or emergency department, not because their condition changed, but because they caught influenza.

Influenza is not the same as the common cold. It arrives with sudden high fever, body aches, and a cough that can persist for weeks. For most healthy adults, it means a miserable week off work. For someone with asthma, it can mean a serious exacerbation, a course of oral steroids, or an unplanned hospital stay.

This article explains why influenza and asthma are a particularly risky combination, what to watch for if you do fall ill, and why annual influenza vaccination is strongly recommended for anyone living with asthma in Singapore.

How Influenza Affects the Airways

To understand why flu hits asthma patients harder, it helps to understand what influenza does to the respiratory system. The influenza virus primarily attacks the cells lining the airways — the same airways that are already chronically inflamed in people with asthma.
When the flu virus enters the respiratory tract, it triggers an intense immune response. The airway lining becomes swollen, the mucus-secreting cells go into overdrive, and the smooth muscle around the bronchial tubes can tighten in response to the viral irritation. In a healthy person, this inflammation is uncomfortable. In a person with asthma, whose airways are already hypersensitive, this cascade of inflammation can dramatically narrow the breathing passages and trigger a severe asthma attack.

According to Singapore’s Ministry of Health, adults and children with chronic pulmonary disorders, including asthma, are among the priority groups at elevated risk of serious influenza complications. The National Centre for Infectious Diseases (NCID) similarly identifies people with chronic respiratory conditions as particularly vulnerable. This recognition at the national level reflects decades of clinical evidence that asthma and influenza interact in ways that go well beyond ordinary illness.

In Singapore, asthma affects approximately 20% of children and 5% of adults, making it one of the most common chronic conditions managed in primary care. With influenza circulating year-round and peaking twice annually — between May and August (broadly aligning with the Southern Hemisphere winter) and again between December and March (broadly aligning with the Northern Hemisphere winter) — the overlap between flu season and asthma risk is not occasional. It is ongoing. (Communicable Diseases Agency Singapore; MOH, Nov 2025)

The Specific Complications That Asthma Patients Face

• For people with asthma, catching influenza raises the risk of several serious outcomes that are far less common in the general healthy population.
• Acute asthma exacerbations are the most immediate concern. The viral infection inflames the already-sensitive airways and can trigger an attack severe enough to require emergency treatment. This is especially true in patients with moderate to severe asthma, or in those whose baseline control is not optimal.
• Secondary bacterial pneumonia is another significant risk. Influenza damages the protective lining of the respiratory tract, making it easier for bacteria such as Streptococcus pneumoniae or Staphylococcus aureus to establish a secondary infection. Pneumonia is in fact the leading cause of influenza-related deaths globally. For asthma patients, who may already have reduced respiratory reserve, pneumonia carries a higher risk of progressing to respiratory failure.
• Prolonged illness and slower recovery are also consistently reported. Asthma patients often find that post-flu cough and wheeze linger for several weeks, even after the viral infection itself has resolved. This extended inflammatory response means more inhaler use, more disruption to daily life, and in some cases, a step-up in asthma therapy.
• Hospitalisation risk is well-documented in asthma patients with influenza. Research has consistently shown that children and adults with asthma are more likely to be admitted to hospital with flu than their peers without respiratory disease. During the 2009 H1N1 pandemic, asthma was among the most commonly reported underlying conditions in hospitalised patients, underscoring how frequently respiratory viruses affect this group and why preventive measures matter.

Recognising an Influenza-Triggered Asthma Flare

Not every bout of coughing during flu season is an emergency, but certain signs indicate that influenza may be worsening your asthma and that medical attention is needed promptly.

Patients should be alert to a pattern where flu symptoms, fever, body aches, runny nose, or sore throat, appear alongside rapidly worsening shortness of breath or wheeze. Needing your reliever inhaler more than twice in a 24-hour period, waking at night due to cough or breathlessness, or finding that your reliever provides less relief than usual are all signs that the illness is affecting your asthma control and should prompt a visit to a doctor.

Seek urgent medical care if you experience any of the following:

• Severe breathlessness that limits speaking in full sentences
• Blue or grey colouring around the lips
• Reliever inhaler providing no improvement after repeated use
• Fever above 39°C alongside chest tightness
• Rapid breathing at rest
• Confusion or drowsiness

These are warning signs of a potentially life-threatening exacerbation and require immediate assessment.

How the Influenza Vaccine Protects Asthma Patients

The most effective preventive measure available to people with asthma is annual influenza vaccination. The flu vaccine works by prompting the immune system to build antibodies against the influenza strains most likely to circulate in the upcoming season, so that if exposure occurs, the body can mount a rapid defence before the virus causes serious illness.

For asthma patients, the rationale for vaccination goes beyond simply avoiding a week of flu symptoms. Influenza is a recognised trigger for asthma exacerbations, and reducing the severity of flu illness reduces the overall inflammatory burden on already-sensitive airways. It is worth noting that clinical trial evidence on whether the vaccine directly reduces the number of asthma exacerbations is inconclusive — the Cochrane systematic review on this question found that uncertainty remains — which is why annual vaccination is framed by MOH and international guidelines as a risk-reduction measure rather than a guarantee. What the vaccine does more reliably is reduce the severity of illness if infection occurs, and lower the risk of serious complications such as secondary bacterial pneumonia.

The influenza vaccine is updated twice a year, aligned with the World Health Organisation’s surveillance of circulating strains. In Singapore, where flu activity spans both Northern and Southern Hemisphere seasons, MOH recommends that at-risk individuals, including those with asthma, consider vaccination for both seasonal windows to maintain the most current protection.

Importantly, the injectable influenza vaccine is not a live vaccine. It cannot cause flu, and it is safe for people with asthma, including those on inhaled corticosteroids. Patients who have had a previous severe allergic reaction to a vaccine component should discuss their suitability with their doctor before proceeding.

Influenza Vaccination in Singapore: What Asthma Patients Should Know

Singapore has a structured national immunisation programme that makes influenza vaccination accessible and affordable for people with asthma.

Under the National Adult Immunisation Schedule (NAIS), individuals with chronic pulmonary conditions including asthma are recommended for annual influenza vaccination. People with asthma are eligible to use MediSave to offset the cost of the vaccine at both polyclinics and CHAS GP clinics. Eligible Singapore Citizens enrolled in Healthier SG who have qualifying medical conditions, including asthma, may receive the influenza vaccination at no cost at their enrolled Healthier SG clinic.

For children with asthma, the National Childhood Immunisation Schedule (NCIS) similarly covers influenza vaccination, and eligible children can receive subsidised or fully covered flu vaccines at CHAS GP clinics and polyclinics.

MOH Circular 71/2025 specifically lists chronic pulmonary disorders, with asthma named as an example, among the qualifying conditions for subsidised influenza vaccination. This means that for most asthma patients in Singapore, the financial barrier to vaccination has been significantly lowered or removed entirely.

Given that influenza in Singapore peaks between May and August (Southern Hemisphere season) and again between December and March (Northern Hemisphere season), the practical recommendation is to get vaccinated before each peak period. (CDA Singapore; MOH; HealthHub) Vaccination takes approximately two weeks to provide protection, so planning ahead makes a meaningful difference.

DR+ Medical & Paincare clinics are CHAS-accredited GP clinics where patients with asthma can consult a doctor about their suitability for influenza vaccination, check their subsidy eligibility, and receive the vaccine in a single visit. For patients already under DR+ care for chronic disease management or asthma, the influenza jab can typically be incorporated into an existing consultation. Learn more about vaccinations and preventive care at DR+ Medical & Paincare or explore our chronic disease management services if your asthma has not been formally reviewed recently.

 

A Doctor’s Perspective: Why Asthma Patients Underestimate Flu Risk

One pattern that GP doctors see repeatedly in practice is the asthma patient who is diligent about their preventer inhaler, avoids cigarette smoke, and keeps their rescue medication close, yet has not had an influenza vaccine in years. The reasoning is often similar: “I don’t get the flu that badly” or “I had the vaccine once and still got sick.”
 
This reflects a common but important misunderstanding. The influenza vaccine does not provide absolute protection against infection, because influenza viruses mutate and new strains emerge each season. What it does is significantly reduce the severity of illness if infection occurs, and specifically for asthma patients, it reduces the chance that a flu episode will spiral into a dangerous exacerbation. A vaccinated asthma patient who does catch flu is far less likely to end up on oral prednisolone or in an emergency department than an unvaccinated counterpart.
 
There is also a timing effect worth understanding. In Singapore’s year-round flu environment, it is not unusual for an asthma patient to get flu between the two peak periods, at a time when immunity from a previous vaccine may have waned. This is one of the practical arguments for considering vaccination for both seasonal windows, particularly for patients with moderate to severe asthma or with a history of flu-triggered attacks.
 
The message from a clinical standpoint is straightforward: managing asthma well includes protecting against the triggers that reliably destabilise it. Influenza is one of the most preventable of those triggers.

Practical Steps for Asthma Patients During Flu Season

Good daily habits complement vaccination but do not replace it. Hand hygiene remains one of the simplest and most effective ways to reduce flu transmission, particularly after contact with commonly touched surfaces in crowded places such as MRT stations, offices, and hawker centres.

Asthma patients should ensure their preventer inhaler technique and dosing are correct before flu season arrives, as suboptimal baseline control increases vulnerability to exacerbation if flu occurs. If you are unsure whether your current asthma treatment plan is optimised, speaking to your GP before the peak season is a sensible step.

Patients who develop flu symptoms should rest, stay well hydrated, and avoid unnecessary contact with others to prevent onward spread. Early review by a doctor is advisable if flu symptoms appear alongside any worsening of asthma control, so that antiviral treatment (such as oseltamivir) can be considered within the therapeutic window, and any step-up in asthma management can be initiated promptly.

These are supportive measures, not substitutes for a proper diagnosis and personalised treatment plan.

When Should You See a Doctor?

If you have asthma and are considering influenza vaccination, a brief consultation with a GP is the right starting point. No referral is required. Your doctor can confirm your suitability for vaccination, advise on timing in relation to the current flu season, and check your MediSave or subsidy eligibility.

If you already have flu-like symptoms and your asthma is worsening, do not wait to see if it improves on its own. Seek medical attention promptly. Flu-triggered asthma exacerbations can escalate quickly, and early treatment consistently leads to better outcomes.
Speak to a DR+ doctor in Singapore today to take the first step toward protecting your lung health this flu season.

Conclusion

For the many Singaporeans living with asthma, influenza is not a nuisance illness to be managed with paracetamol and a few days off work. It is a genuine clinical risk that can trigger severe attacks, lead to pneumonia, and result in hospitalisation. The good news is that annual influenza vaccination is safe, recommended, and subsidised for asthma patients in Singapore, making prevention both practical and accessible.
Whether your asthma is mild or moderate, well-controlled or still being optimised, getting the flu jab each year is one of the most direct steps you can take to protect the breathing you depend on. Book a consultation with the DR+ team to discuss your vaccination and asthma management needs.

Frequently Asked Questions

Can people with asthma safely receive the influenza vaccine?

Yes. The injectable influenza vaccine is an inactivated vaccine, which means it does not contain live virus and cannot cause flu. It is safe for people with asthma, including those taking inhaled corticosteroids. The only exception is for individuals with a known severe allergy to a specific vaccine component, who should discuss their options with their doctor before vaccination. For the vast majority of asthma patients, the benefits of the flu jab substantially outweigh any risks.

Why is influenza more dangerous for people with asthma?

The influenza virus directly inflames the airway lining, which is already chronically sensitive in asthma. This combination of viral inflammation on top of existing airway hypersensitivity can trigger severe asthma attacks, prolong illness, and significantly increase the risk of secondary bacterial pneumonia. Asthma is among the most commonly reported underlying conditions in patients hospitalised with influenza, and the disease is a well-recognised trigger for exacerbations, which is why preventive vaccination is recommended for this group.

How often should people with asthma get the flu jab in Singapore?

MOH recommends annual influenza vaccination for people with chronic pulmonary conditions, including asthma. Because influenza strains change each season and immunity wanes over time, a yearly jab is necessary to maintain protection. In Singapore, influenza circulates year-round with two distinct peak periods: May to August and December to March. (CDA Singapore; MOH; HealthHub) Patients may wish to consider vaccination before each peak period. Speak to your GP about the most appropriate timing for your individual situation.

Is the influenza vaccine subsidised for asthma patients in Singapore?

Yes. Under the National Adult Immunisation Schedule (NAIS), people with chronic pulmonary disorders including asthma qualify for subsidised influenza vaccination at CHAS GP clinics and polyclinics. MediSave may also be used to cover the remaining co-payment. Eligible Singapore Citizens enrolled in Healthier SG with qualifying medical conditions, including asthma, may receive the flu vaccination at no cost at their enrolled clinic. Children with asthma are similarly eligible under the National Childhood Immunisation Schedule (NCIS).

What should I do if I get influenza and my asthma symptoms worsen?

See a doctor promptly. Do not wait to see if symptoms resolve on their own. Your GP can assess whether antiviral medication such as oseltamivir is appropriate, which is most effective when started within the first 48 hours of symptoms. They can also review your current asthma medications and adjust your treatment plan if needed. If you experience severe breathlessness, lips turning blue, or your reliever inhaler is providing no relief, seek emergency care immediately.

About DR+ Medical & Paincare

DR+ Medical & Paincare is a network of GP and pain management clinics across Singapore, operated under Singapore Paincare Holdings. DR+ clinics provide comprehensive primary care, chronic disease management, health screening, and vaccinations. DR+ is a CHAS-accredited provider participating in the Healthier SG programme.

Medical Disclaimer: This article is intended for general informational purposes only and does not constitute medical advice. Please consult a qualified healthcare professional for diagnosis and treatment tailored to your individual condition.