3 March 2021

COVID vaccine side effects: what to expect

COVID-19 Vaccination

Headache, fatigue and soreness at injection site are the most common side-effects of the Pfizer vaccine experienced by Australians, according to the first weekly report on COVID-19 vaccine safety.

As vaccination efforts ramp up, the Therapeutic Goods Administration (TGA) has implemented a number of changes, such as requiring general practices and pharmacies to commit to providing real-time reporting of adverse events post-immunisation.

With about 33,700 doses now delivered, more than 7000 people have responded to a short SMS survey sent out by the government funded surveillance system, AusVaxSafety, since the first dose of the Pfizer vaccine was administered on 21 February.

Just over one third reported side effects, with the most commonly reported effect being injection site pain, which was reported 2,153 times.

Fatigue and headache were the next most-reported side effects, with 1,328 and 1,008 reports, respectively.

These symptoms were all identified as very common side effects in vaccine trials.

Less common were muscle aches (750 reports), injection site swelling (391 reports), joint pain (278 reports) and chills (241 reports).

Real world safety data has also been growing over the past two months from vaccine programs in countries such as Israel and the UK.

The UK, which captures data using an optional consumer survey similar to AusVaxSafety, has so far recorded more than 31,400 adverse events related to the almost seven million doses of the AstraZeneca vaccine which have been given so far.

Almost 27,000 adverse events have been recorded from the near nine million Pfizer vaccine doses given.

According to the UK Medicines & Healthcare Products Regulatory Agency (MHRA), these figures equate to between three and five adverse event reports per 1,000 doses given of either vaccine.

The preliminary data so far shows the most common adverse events recorded in the UK, either injection-site reactions or generalised flu-like symptoms, are similar for both vaccines.

For the AstraZeneca vaccine specifically, a higher number of reports identified adverse effects relating to:

  • Pyrexia (fever), identified in 11,113 adverse events as opposed to 4,477 Pfizer adverse events
  • Chills, identified in 8,373 adverse events, but only 2,883 Pfizer adverse events
  • Nausea, included in 6036 adverse event reports but 3,652 Pfizer reports
  • Influenza-like illness, identified in 1,762 adverse events, and 630 Pfizer adverse events.

Meanwhile, adverse event reports related to the Pfizer vaccine were higher for:

  • Anaphylactic reactions, of which there have been 168 for Pfizer compared with 105 for AstraZeneca
  • Lyphadenophathy (swelling of the lymph nodes), identified in 1,536  adverse events, but only 476 AstraZenca  adverse events.

No anaphylaxis deaths related to the vaccine have been recorded in the UK to date.

The MHRA stressed not all the adverse events reported were necessarily caused by the vaccine, and many might be due to underlying illness.

Israel, which has only been using the Pfizer vaccine, has recorded a total of 234 allergic or anaphylactic reactions after giving more than three million vaccinations, as reported by The Jerusalem Post.

Only 48 Israeli citizens have experienced adverse events which were severe enough to require hospitalisation; 19 of these hospitalisations were related to a history of cardiac disease, while 11 were related to central nervous system issues.

All other cases requiring hospitalisation were believed to be linked to underlying illnesses.

The majority of side-effects from the vaccine in Israel were experienced by a younger cohort, people aged 20 to 60.

Australia’s vaccine safety data will be published weekly by AusVaxSafety and the TGA.

AusVaxSafety, a government-funded initiative operated by the National Centre for Immunisation Research and Surveillance, will also be sending vaccine recipients follow-up text messages with a survey to screen for any potential side effects; this data will then be released weekly.

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