Nothing in medicine is 100% safe – even something we take without thinking, like paracetamol, poses risks. 

Like all medicines, this vaccine can cause side effects, although not everybody gets them. In clinical studies with the vaccine, most side effects were mild to moderate in nature and resolved within a few days with some still present a week after vaccination. 

If side effects such as pain and/or fever are troublesome, medicines containing paracetamol can be taken. But always speak to a doctor first. 

Side effects that occurred during clinical trials with the Oxford University / AstraZeneca were as follows: 

Very Common (may affect more than 1 in 10 people) 

• tenderness, pain, warmth, redness, itching, swelling or bruising where the injection is given 
• generally feeling unwell 
• feeling tired (fatigue) 
• chills or feeling feverish 
• headache  
• feeling sick (nausea) 
• joint pain or muscle ache 

Common (may affect up to 1 in 10 people) 

• a lump at the injection site 
• fever 
• being sick (vomiting) 
• flu-like symptoms, such as high temperature, sore throat, runny nose, cough and chills 

Uncommon (may affect up to 1 in 100 people) 

• feeling dizzy 
• decreased appetite 
• abdominal pain 
• enlarged lymph nodes 
• excessive sweating, itchy skin or rash In clinical trials there were very rare reports of events associated with inflammation of the nervous system, which may cause numbness, pins and needles, and/or loss of feeling. However, it is not confirmed whether these events were due to the vaccine. 

If you notice any side effects not mentioned in this leaflet, please inform your doctor, pharmacist or nurse.

Do NOT take the vaccine: 

• If you have ever had a severe allergic reaction to any of the active substances or any of the other ingredient. Signs of an allergic reaction may include itchy skin rash, shortness of breath and swelling of the face or tongue. Contact your doctor or healthcare professional immediately or go to the nearest hospital emergency department right away if you have an allergic reaction. It can be life-threatening. If you are not sure, talk to your doctor, pharmacist or nurse.

Warnings and precautions  

Tell your doctor, pharmacist or nurse before vaccination: 

• If you have ever had a severe allergic reaction (anaphylaxis) after any other vaccine injection;  
• If you currently have a severe infection with a high temperature (over 38°C). However, a mild fever or infection, like a cold, are not reasons to delay vaccination;
• If you have a problem with bleeding or bruising, or if you are taking a blood thinning medicine (anticoagulant); 
• If your immune system does not work properly (immunodeficiency) or you are taking medicines that weaken the immune system (such as high-dose corticosteroids, immunosuppressants or cancer medicines). 

If you are not sure if any of the above applies to you, talk to your doctor, pharmacist or nurse before you are given the vaccine.

As with any vaccine, this vaccine may not fully protect all those who receive it. 

No data are currently available in individuals with a weakened immune system or who are taking chronic treatment that suppresses or prevents immune responses.

SOURCE: 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/948335/Information_for_UK_recipients_COVID-19_Vaccine_AstraZeneca.pdf

Pfizer / BioNTech

Like all medicines, this vaccine can cause side effects, although not everybody gets them. Most side effects go away within a few days of appearing. If side effects such as pain and/or fever are troublesome, they can be treated by medicines for pain and fever such as paracetamol. 

You may very rarely experience a severe allergic reaction after receiving this vaccine. Signs of an allergic reaction may include itchy skin rash, shortness of breath and swelling of the face or tongue. Contact your doctor or healthcare professional immediately or go to the nearest hospital emergency department right away if you have an allergic reaction. It can be life-threatening. 

Other side effects can include:

Very common (may affect more than 1 in 10 people): 

• Tenderness and swelling of the underarm glands on the same side as the injection site 
• Headache
• Nausea
• Vomiting 
• Muscle ache, joint aches, and stiffness 
• Pain or swelling at the injection site
• Feeling very tired
• Chills 
• Fever 

Common (may affect up to 1 in 10 people):

• Rash 
• Rash, redness, or hives at the injection site

Uncommon (may affect up to 1 in 100 people): 

• Itchiness at the injection site 

Rare (may affect up to 1 in 1000 people)

• Temporary one-sided facial drooping (Bell’s palsy
• Swelling of the face (Swelling of the face may occur in patients who have had facial cosmetic injections.) 

Frequency unknown

• Severe allergic reactions (anaphylaxis) 
• Hypersensitivity 

Do NOT have the vaccine if

• you are allergic to the active substance or any of the other ingredients of this vaccine

Warnings and precautions 

Talk to your doctor, pharmacist or nurse before you are given this vaccine if you: 

• Have any allergies. If you have experienced a severe allergic reaction after the first dose of this vaccine, you should not receive a second dose. 
• Have a very weak or compromised immune system, such as due to HIV infection, or are on a medicine that affects your immune system 
• Have a bleeding problem, bruise easily or use a medicine to inhibit blood clotting 
• Have a high fever or severe infection. However, a mild fever or upper airway infection, like a cold, are not reasons to delay vaccination. 
• Have any serious illness 

If any of the above apply to you (or you are not sure), talk to your doctor, pharmacist or nurse before you are given the Moderna vaccine.  

Source: 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/950665/Moderna_Information_Recipient_updated.pdf