Astrazeneca vaccine effectiveness, side effects and other facts

AstraZeneca Vaccine

AstraZeneca vaccine is a covid 19 vaccine. It helps our body to build a protective immunity against coronavirus infection. So this vaccine will prevent covid 19.

This vaccine will stimulate our body’s immune system to produce antibodies against the coronavirus, so in the future, if coronavirus infects us, our already prepared immune system will fight against the virus and will protect us from the dreadful coronavirus.

Here it is important to mention that none of the ingredients of this AstraZeneca vaccine can cause coronavirus infection or covid 19. 

AstraZeneca Vaccine type

AstraZeneca vaccine is a viral vector based vaccine.

AstraZeneca Vaccine ingredients

The solution of this vaccine is colorless to slightly brown, clear to slightly opaque.

AstraZeneca vaccine contains the following

  • Each dose (0.5ml) contains covid 19 vaccine ( ChAdOx1-S recombinant) 5X 1010 viral particles (vp)

Recombinant, replication-deficient chimpanzee adenovirus vector that encodes SARS-CoV-2 Spike glycoprotein (S glycoprotein). It is produced in genetically modified human embryonic kidney (HEK) 293 cells.

  • The genetically modified organisms(GMOs).
  • L-histidine
  • L- histidine hydrochloride monohydrate
  • Magnesium chloride hexahydrate
  • Polysorbate 80 (E 433)
  • Ethanol
  • Sucrose
  • Sodium chloride
  • Disodium edetate dihydrate
  • Water for injection

AstraZeneca Vaccine dose

The AstraZeneca vaccine is given through the intramuscular route into the muscle of the upper arm. The muscle is preferably deltoid muscle.

Similar like Covaxin, Covishield, Pfizer BioNTech, Moderna, Sputnik V AstraZeneca covid vaccine is also a two dose vaccine. Each dose contains 0.5 ml of the vaccine.

If you receive the first dose of the AstraZeneca vaccine, then you should receive the second dose only with the AstraZeneca vaccine. You should not receive any other covid 19 vaccines as your second dose.

AstraZeneca Vaccine timing between two dose

The second dose of the AstraZeneca vaccine is given between 4 and 12 weeks after the first shot.

Always complete your vaccination regimen. If you receive the first dose, then don’t forget to take the second dose of this vaccine within the recommended time period.

AstraZeneca Vaccine effectiveness

As per a study of phase three clinical trial in the UK, the effectiveness of AstraZeneca vaccine is 70.4 percent to prevent symptomatic covid 19 against the alpha variant of coronavirus, 14 days after getting the second dose.

AstraZeneca Vaccine and delta variant

As per a study published in the New England Journal of Medicine, two doses of AstraZeneca vaccine is 67percent effective against the delta variant of coronavirus, up from 60 percent originally reported.

Who can get AstraZeneca Vaccine?

The AstraZeneca vaccine is recommended for use in people older than 18 years.

Who should not get AstraZeneca Vaccine?

You should not receive the AstraZeneca vaccine if

  1. You are allergic to any ingredients of this vaccine
  2. You experienced blood clot simultaneously with low levels of platelets (Thrombosis with thrombocytopenia syndrome) after receiving the first dose of AstraZeneca vaccine
  3. You have a history of capillary leak syndrome. Capillary leak syndrome is a condition where there is fluid leakage from small blood vessels.
  4. If you experienced severe allergic reactions (anaphylaxis) after receiving the first dose of the AstraZeneca vaccine.
  5. If you have already received other covid 19 vaccines.

AstraZeneca vaccine warnings and precautions

 Before getting the AstraZeneca vaccine shot, tell your vaccine provider if you have any of the listed issues previously.

  • You experienced a severe allergic reaction after any other vaccine shot or after you received the covid 19 AstraZeneca vaccine before.

 The signs of an allergic reaction are

Itchy skin rash, Shortness of breath, swelling of the face or tongue.

In case of any allergic reaction, seek medical help immediately.

  • You have ever fainted after any needle injection.
  • You are currently having a high temperature (more than 38 degree C) with a severe infection. But you should not delay vaccination if you have mild fever or infection such as a cold.
  • You have a history of heparin-induced thrombocytopenia and thrombosis (HITT or HIT type 2).
  • You have a history of blood clot in the sinus veins in the brain.
  • You have a bleeding disorder.
  • You have a problem with bruising or you are under a blood thinning medicine (anticoagulant).
  • You have a weak immune system (immune deficiency) or you are under medication that weakens your immune system (for example high dose corticosteroids, immunosuppressants, or cancer medicine).

Blood disorders

After the vaccination with the AstraZeneca covid 19 vaccine, there are extremely rare reports of blood clots with low levels of platelets (thrombosis with thrombocytopenia syndrome). This includes severe cases of blood clots in unusual locations and excessive bleeding or clotting throughout the body. Most of these cases happened within the first three weeks after getting the vaccine. But there are also reports that for some people this happened after three weeks. Few times, these cases may turn to life threatening.

If you experience the following symptoms from around 4 days after getting the AstraZeneca vaccine, then you should seek immediate medical attention. The symptoms are

  1. A severe headache that is getting worse when you lie down or bend over.
  2. A severe headache that is not relieved by simple pain killers.
  3. Headache with blurred vision, confusion, speech difficulty, weakness, drowsiness, or seizures.
  4. Rash with small bruising or bleeding under the skin beyond the site of injection.
  5. Shortness of breath
  6. Chest pain
  7. Tummy pain (abdominal pain) that is persistent
  8. Leg pain 
  9. Leg swelling
  10. Unusual tiredness or fatigue

Capillary Leak Syndrome:

Capillary Leak Syndrome is a serious, life threatening condition that causes fluid leakage from small blood vessels or capillaries. This results in rapid swelling of the arms or legs, sudden weight gain, low blood pressure, fainting, etc. Always seek immediate medical help if you experience these symptoms in the days after getting the AstraZeneca vaccine.

AstraZeneca vaccine side effects 

The following are the side effects of the AstraZeneca vaccine

Very common side effects

Very common side effects may affect more than 1 in 10 people

  1. Pain, itching, redness, bruising, warmth at the injection site
  2. Fatigue or Feeling tired 
  3. Chills
  4. Feeling unwell
  5. Feeling Feverish 
  6. Headache
  7. Muscle pain or joint pain
  8. Nausea

Common side effects

Common side effects may occur up to 1 in 10 people.

  1. Swelling, lump, or redness at the injection site
  2. Vomiting
  3. Diarrhea
  4. Fever ( temperature more than 38 degree C)
  5. Pain in legs or arms
  6. Sore throat
  7. Runny nose
  8. Cough
  9. Chills
  10. Feeling sick

Some people reported a sudden feeling of cold with shivering/shaking accompanied by increased temperature associated with sweating, headache (also includes migraine like a headache), nausea, muscle aches, feeling unwell. All these started within a day after getting the vaccine and usually go away within 1-2 days.

If your fever is high and continues more than 2-3 days or you have other symptoms persisting after getting the vaccine, then maybe these are not side effects due to the vaccine. In that case, you should seek medical help.

Uncommon side effects

Uncommon side effects may occur up to 1 in 100 people.

  1. Feeling dizzy or sleepiness
  2. Belly pain (abdominal pain)
  3. Reduced appetite
  4. Enlarged lymph nodes
  5. Excessive sweating
  6. Itchy skin, rash, or hives

Very rare side effects

Very rare side effects may develop in up to 1 in 10,000 people.

There are very rare reports of blood clots with low levels of blood platelets. These blood clots when occur, the location may be unusual such as brain, liver, bowel, spleen.

Not known side effects

Not known side effects (side effects can not be estimated from the available data)

  1. Severe allergic reactions ( also known as anaphylaxis)
  2. Rapid swelling of face, lip, mouth, throat. Swelling in these regions may cause difficulty in swallowing or breathing. This condition is also known as angioedema.
  3. Low blood platelets (also known as thrombocytopenia)
  4. Hypersensitivity
  5. Capillary leak syndrome. It is a condition that causes leakage of fluid from small blood vessels.

In clinical trials, there are very rare reports of cases associated with inflammation of the nervous system. This may cause numbness, pins, and needles feeling, loss of feeling. But it is not confirmed to date if all these symptoms are due to the vaccine or not.

Get emergency medical help if you get symptoms of severe allergic reactions. The symptoms are- Feeling faint or light headed, Shortness of breath or wheezing (a whistling sound in the airway), changes in heartbeat, rash or hives, swelling of face, lip, mouth, or throat, nausea or vomiting, stomach pain.

In clinical trial reports, it is seen that side effects after the second dose are fewer as compared to the first dose of the AstraZeneca vaccine. Also, side effects after the second dose are milder as compared to the first dose.

If there is fever or pain as a side effect of the vaccine, paracetamol can be taken.


AstraZeneca vaccine is a two dose covid 19 vaccine. Clinical trial report shows this vaccine is apparently safe to use. Though there are conflicting reports about capillary leak syndrome and blood disorders after getting the AstraZeneca vaccine, more research is needed to give a final conclusion that whether this vaccine is solely responsible for those serious side effects. Still, it is better to go for other covid 19 vaccines such as Moderna, Sputnik V, Johnson and Johnson, Covaxin, etc. if you have a history of blood disorder or capillary leak syndrome. Interim trial data of AstraZeneca shows that this vaccine is 80 percent effective to prevent covid 19 in people who are older than 65 years. With time more data will come. You can go through our other covid 19 vaccine articles before taking the final decision that which vaccine will suit you best. Stay healthy and happy.


  1. Government of United Kingdom Publication
  2. AstraZeneca Official Website
  3. Nature Journal
  4. WHO
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