Influenza (Flu) Vaccine: Purpose, Dose, Safety and Follow-up
By Dr Jehangir Khan, Consultant Pulmonologist · Reviewed by Dr Muhammad Israr · Updated 4 Oct 2026
- Influvac is in short supply this season.
- At IRC we advise Vaxigrip or Anflu, whichever is available.
- For maximum protection in high-risk patients, Dr Jehangir Khan advises two doses of Anflu, one month apart.
- The goal of vaccination is to prevent flu complications, above all pneumonia, and to reduce deaths.
Why flu vaccination matters
Flu is not just a bad cold. The influenza virus infects the airways and can cause viral pneumonia, or weaken the lungs so that bacteria cause a second pneumonia. It can also trigger asthma and COPD attacks, worsen heart failure and diabetes, and raise the risk of heart attack in the weeks after infection. In Pakistan, flu is most common in the winter months. The vaccine does not always stop infection, but vaccinated people who do catch flu are less likely to develop pneumonia, need hospital care or die.
Purpose of the vaccine
- Prevent influenza illness, or make it milder and shorter
- Prevent pneumonia and other complications
- Reduce hospital admissions and deaths, especially in the elderly and people with chronic disease
- Prevent asthma and COPD flare-ups caused by flu
- Protect people around you, such as babies and elderly relatives
Which vaccine this season?
| Vaccine | This season at IRC |
|---|---|
| Influvac | In short supply |
| Vaxigrip | Advised. One dose for most adults. |
| Anflu | Advised. Two doses one month apart for high-risk patients, as recommended by Dr Jehangir Khan. |
Age limits differ by product, so check the label with the clinic. Stock changes often, so call before you come.
Who should get it? (Indications)
- Adults aged 65 and over
- Children aged 6 months to 5 years
- Pregnant women, in any trimester
- Chronic lung disease: asthma, COPD, bronchiectasis, past TB damage
- Heart disease, diabetes, kidney or liver disease, severe obesity
- Anyone with a lingering cough or breathlessness: check your lungs first with lung function tests
- Weak immunity: HIV, long-term steroids, chemotherapy, transplant
- Healthcare workers, carers of high-risk people, and Hajj or Umrah pilgrims
- Anyone who wants to lower their risk of flu
Dose, route and schedule
| Item | Detail |
|---|---|
| Type | Inactivated (killed) vaccine. It cannot give you flu. |
| Dose | 0.5 mL for adults and older children. For infants and toddlers, dose and minimum age depend on the product label. |
| Route | Intramuscular injection in the upper arm (deltoid). Thigh in infants. Never into a vein. |
| When | Before winter, ideally September to November. Protection builds in about 2 weeks. Later is still worthwhile. |
| How often | Every year, because flu strains change and protection fades. |
| Standard schedule | Most adults: 1 dose a year. Children under 9 having flu vaccine for the first time: 2 doses at least 4 weeks apart. |
| IRC high-risk advice | 2 doses of Anflu, one month apart, for maximum protection. |
The second dose in adults goes beyond the standard international schedule, and good evidence for it is still limited. It is not harmful, and your doctor will decide whether it suits you.
Contraindications and precautions
- Do not give if you had a severe allergic reaction (anaphylaxis) to a previous flu vaccine or to any ingredient.
- Postpone if you have a fever or a moderate to severe illness. A mild cold is not a reason to delay.
- Tell the doctor about egg allergy. Most people can still be vaccinated, with 15 to 30 minutes of observation.
- Tell the doctor about Guillain-Barré syndrome, bleeding disorders or blood thinners. Pressure on the site for 2 minutes helps.
- Pregnancy is not a contraindication. The vaccine is recommended.
Side effects
- Common, 1 to 2 days: pain, redness or swelling at the injection site, mild fever, headache, muscle aches, tiredness. This is not flu.
- Fainting can happen, especially in teenagers. Sit for 15 minutes afterwards.
- Rare: serious allergy (hives, swollen face, wheeze, breathlessness), usually within minutes to hours. This is an emergency.
- Very rare: Guillain-Barré syndrome, about 1 to 2 cases per million doses.
After the vaccine: follow-up
- Stay at the clinic for 15 minutes after the injection.
- For pain or fever, take paracetamol and move your arm. Do not use aspirin in children.
- Protection starts after about 2 weeks. Until then, wash hands and avoid sick contacts.
- If a second dose is advised, book it for 4 weeks later.
- Repeat the vaccine every year. Adults 65 and over and people with lung disease should also ask about the pneumococcal vaccine, which prevents bacterial pneumonia.
- If you still get flu symptoms (fever, cough, body aches), see a doctor early. Antiviral treatment works best within 48 hours, especially in high-risk patients.
- Go to emergency for breathlessness, chest pain, blue lips, confusion or a fever lasting more than 3 days.
Common questions
Can the flu vaccine give me flu?
No. It contains killed virus. Mild aches for a day or two are the immune system responding.
If I am vaccinated, can I still get flu?
Yes, but usually a milder illness with fewer complications. The vaccine also does not protect against the common cold or COVID-19.
Is it safe to take Vaxigrip or Anflu with other vaccines?
Usually yes, at a different injection site. Tell the doctor which vaccines you are due for.
Related guides
- Asthma in Islamabad: symptoms, diagnosis and treatment
- Inhalers for asthma: treatment and technique
- COPD treatment in Islamabad
- Pulmonary function tests at IRC
- Allergy testing in Islamabad
- TB symptoms and treatment
- Islamabad Respiratory Clinic home
Medical information: For general education only. It does not replace a consultation. Vaccine choice and schedule should be decided by your doctor, and the product label applies. Islamabad Respiratory Clinic (IRC) · Saeed International Hospital, 1 Hospital Road, G-11 Markaz, Islamabad · 0343 1510025 · ircchest@gmail.com · یہ صفحہ اردو میں پڑھیں