What side effects to expect after a COVID-19 vaccination

COVID-19 vaccines give us the protection we need to go about our daily lives but, understandably, many people have questions around these vaccines and their side effects. We spoke to nib group medical advisor Dr Hamish Black about vaccine safety, any potential side effects, and what to do if you experience them.

All vaccines approved for use in Australia are extremely safe. In fact, every vaccine – not just those used in the fight against COVID-19 – goes through rigorous testing and research to be approved for use in the community.

“There have been more than 4 billion doses given around the world now, so we know a lot about these vaccines,” says Hamish. “The chance of death in Australia after these vaccines is less than five in a million.”

The COVID-19 vaccines used in Australia – Pfizer, AstraZeneca (also known as Vaxzevria), and now Moderna – are constantly under review by our regulatory body, the Therapeutic Goods Administration (TGA), as well as the manufacturers, to ensure the community’s health and safety.

“The most important thing to realise about these vaccines is they are some of the best vaccines humankind has produced,” says Hamish. “They are incredibly effective– you are about 30 times more likely to be admitted to hospital with COVID-19 if you’re unvaccinated than if you’re vaccinated.”

While it may seem that the COVID-19 vaccines were developed quickly, this does not take away from their safety or efficacy. Collaboration from experts around the world meant they were able to be created, trialled and delivered faster than vaccines in the past, and with scientists, manufacturers and distributors around the world all working together, the development and implementation stages happened simultaneously, rather than one after the other, as they would normally. This meant the process was finished faster – but with no compromise on safety and quality.

Since mid-September 2021, three COVID-19 vaccines have been made available in Australia and all have been shown to be highly effective in not only preventing COVID-19, but also reducing death and the need for hospitalisation among those who do catch the virus – which, says Hamish, we probably all will at some stage.

No vaccine – for COVID-19 or other illnesses – is 100% effective, so you may still catch the virus after being vaccinated. But the vaccines significantly reduce your chances of suffering serious illness or dying from COVID-19. For example, people who had two doses of a Pfizer COVID-19 vaccine were about 95% less likely to get symptomatic COVID-19 than people who did not get the vaccine.

The most common side effects for all the COVID-19 vaccine options are flu-like symptoms,  such as pain, redness or swelling where you received the injection, headache and mild fever.

“The day after the injection, it is common to feel lethargic and have generalised aches and even a low-grade fever,” says Hamish. “It’s a good idea not to plan much for that day – you may need a day off work. This tends to happen more so after the first dose with AstraZeneca and after the second dose with Pfizer.”

While there are more serious side effects they are extremely rare. Allergic reactions usually occur within 15 minutes of receiving your vaccine, which is why you’ll be asked to wait at your doctor’s office or vaccination hub for 15 to 30 minutes afterwards.

One rare side effect that has received a lot of media attention is the link between the AstraZeneca vaccine and a blood-clotting disorder called thrombosis with thrombocytopenia syndrome (TTS). However, the risk of TTS after the AstraZeneca vaccine is minimal – around one in 100,000 – “and the risk of death is less than one in 1 million [in Australia]”, Hamish says.

The risk of blood clotting if you catch COVID-19, however, is much higher – more than one in 10 people hospitalised with the virus develop blood clotting issues.

TTS is also treatable which is why it’s important to speak to your healthcare professional immediately if you notice any of the following symptoms:

• A headache that keeps coming back, whether mild or strong. It may feel worse when you lie down and it might go away with pain relief medication, but then come back again

• Nausea or vomiting

• Blurred vision, difficulty speaking, drowsiness or confusion, seizures

• Persistent stomach pain

• Shortness of breath or chest pain

• Swelling, pain or redness in your lower limbs

• Tiny blood spots under the skin away from the area where you had your injection

Note: An increased risk of TTS hasn’t been linked to mRNA vaccines such as Pfizer and Moderna.

The good news is that the side effects generally don't last very long.

The typical side effects usually last only one or two days and can be well managed using over-the-counter pain relief

“You can use ibuprofen and paracetamol to help ease some of these symptoms, such as headaches and joint pain,” says Hamish. “Most importantly, rest and get plenty of fluids the day after the injection.”

Use the government’s Covid-19 Vaccine Side Effect Checker if you’re experiencing symptoms you’re unsure about following your vaccination. If you have any kind of reaction that you feel is severe or unexpected, or you’re concerned in any way after your vaccination, speak to your GP.

And if you experience any of these symptoms, get medical attention immediately, either by seeing your doctor or going to a hospital:

• Shortness of breath

• Pain in the chest or belly (especially if it’s persistent)

• Leg swelling

• Severe and persistent headaches or blurred vision

• Tiny blood spots under the skin other than at the injection site.

Please note: The information throughout this article should not replace any advice you have been given by your medical practitioner.