COVID-19 vaccine hesitancy despite mounting evidence of effectiveness, efficacy, and safety

The benefits associated with COVID-19 vaccine administration – both Pfizer (Comirnaty) and AstraZeneca – outweigh the potential risk of adverse reactions and side effects.

Key points

  • The Pfizer/Comirnaty and Oxford/AstraZeneca vaccines are safe and efficacious vaccines with emerging evidence confirming earlier findings.
  • Hesitancy to receive COVID-19 vaccines risks not achieving sufficient population level/herd immunity to protect members of the community.
  • The benefits associated with COVID-19 vaccine administration (both Pfizer/Comirnaty and Oxford/AstraZeneca) outweigh the small but potential risks of serious adverse reactions.
  • Severe reactions to COVID-19 vaccines are extremely rare and typically occur within the first 15 minutes following vaccination.
  • The vast majority of reactions to COVID-19 vaccines are mild, only last a day or two, and are typical reactions to any vaccine.
  • The development of blood clots (thrombosis with thrombocytopenia) following administration of the Oxford/AstraZeneca vaccine is extremely rare (around 4-6 people per million).
  • Awareness of and monitoring for adverse reactions is important to ensure patient safety.
  • Nurses and midwives are key players in ensuring that colleagues, patients, and community members are able to make informed, evidence-based decisions regarding COVID-19 vaccines.

The Australian COVID-19 vaccine rollout is progressing with Phase 2a commencing in May. Phase 2a includes; people aged over 50, Aboriginal and Torres Strait Islander adults aged 18-49 years, and other critical and high risk workers. While the rollout has been impacted by delays, the vaccines are safe and efficacious for protecting people against the risk of developing severe COVID-19 infection.

Despite the increasing volume and clarity of evidence showing the benefits and low-risk of COVID-19 vaccination, many people including nurses are hesitant to receive them.1-5 Nurses Vaccine hesitancy is a complex phenomenon not solely related to the COVID-19 vaccine.6 Hesitancy can be related to concerns regarding vaccine effectiveness, risk of reactions, engagement with social media, fake news, and assessment of the risk of COVID-19 infection.7-10

Healthcare professionals including nurses and midwives are key players in educating and informing colleagues, patients, and the community regarding the evidence about COVID-19 vaccines to support wider community awareness and uptake of vaccines.

COVID-19 vaccines in Australia

The Australian Therapeutic Goods Administration (TGA) has provisionally approved two safe, efficacious vaccines for administration in Australia; the Pfizer/Comirnaty mRNA-based vaccine,11 and the Oxford/AstraZeneca viral vector vaccine.12 Safety and efficacy is determined through analysis of ongoing clinical trials, international collaboration, and advice from the Advisory Committee on Vaccines (ACV). As with other international organisations, the TGA continually monitors the safety, quality, and efficacy of all vaccines before and following provisional approval and closely investigates even rare or minor reactions.13,14

Vaccine safety, efficacy, and effectiveness


Confirming previous results,12,15,16 a recently completed Phase III trial of the AstraZeneca vaccine with 32,449 participants has demonstrated the efficacy and safety with 76 percent efficacy (Confidence Interval (CI): 68%-82%) at 15 days or more following two doses given four weeks apart for preventing symptomatic COVID-19. For adults aged 65 and older, this jumped to 85 percent (CI: 58% to 95%). Importantly, results showed 100 percent efficacy for preventing severe or critical disease and hospitalisation. No safety concerns related to the vaccine were reported.17

Pfizer (Comirnaty)

Confirming the results of previous Pfizer (Comirnaty) trials,18 recent Phase III trial results of 46,307 participants including 927 confirmed symptomatic cases have shown 91.3 percent efficacy (CI: 89% – 93.2%) against COVID-19 from seven days to six months following the second dose. According to United States Centers for Disease Control and Prevention criteria, the vaccine has been shown to be 100 percent effective (CI: 88% – 100%) in preventing severe disease. Further, the safety and tolerability of the Pfizer (Comirnaty) vaccine has been found to be high with no serious safety concerns noted among 44,000 participants including over 12,000 participants at six months or longer following the second dose. As vaccine rollouts progress, evidence from the ‘real world’ (as opposed to clinical trials) suggest that the Pfizer vaccine is effective for reducing risk of infection, symptomatic COVID-19, hospitalisation, and severe disease.19-21 In another study of 417 participants,22 receipt of the Pfizer-BioNTech or Moderna COVID-19 vaccines was found to be 94 percent effective (CI: 49% – 99%) against COVID-19 hospitalisation among fully vaccinated adults and 64 percent (CI: 28% – 82%) effective among partially vaccinated adults aged ≥65 years.[1]

[1] Pfizer-BioNTech is the name used for the Pfizer vaccine in the United States. The Moderna vaccine is not currently available in Australia.

Vaccine reactions

Mild reactions

Many vaccines including those for COVID-19 can cause reactions.23,24  Most often, reactions are mild and will disappear within a couple of days. Common reactions include:15,23 25

  • Injection site pain, redness, or swelling
  • mild fever
  • headache

Less common reactions can include flu-like symptoms such as muscle aches, chills/fever, nausea, or fatigue.15,23 This is not a mild COVID-19 infection but can last for a few days. Evidence shows that people seem to experience these flu-like symptoms more often after the second dose of the Pfizer (COMIRNATY) vaccine or the first dose of the AstraZeneca vaccine.

Treating mild reactions

Most mild reactions go away within a day or two after vaccination. Some people can experience reactions for a few days longer. In most people, no treatment is required and everyday activities and comfort unaffected. For mild flu-like symptoms, commonly available pain relief medication (i.e. supermarket or pharmacy), rest, and maintaining adequate hydration and a comfortable body temperature is effective for reducing discomfort.23

Allergic reactions

Allergic reactions to COVID-19 vaccines are rare. For some people, the injection site could become more painful, swollen, or red even after 24 hours following vaccination. Very rarely, this might include a rash, itching, or more extensive swelling (ie. limb swelling).26,27 If this occurs, or if other mild symptoms above do not go away or get worse after a few days, healthcare professional advice should be sought.

If a person is known to be allergic to an ingredient in one of the vaccines – polyethylene glycol (PEG) in the Pfizer/Comirnaty vaccine)28 or polysorbate, an ingredient in the AstraZeneca vaccine, 29 they should not receive that vaccine. It appears that unless a person has experienced an allergic reaction to the first dose of a COVID-19 vaccination or an ingredient known to be contained within the COVID-19 in question, it is likely that people who have a history of allergic reactions to other, non-COVID-19 vaccines or other sources can still be safely vaccinated.30

Non-severe allergic reactions

Non-severe, immediate allergic reactions are rare following COVID-19 vaccination.26 These reactions usually occur within a few hours and include hives, swelling, and wheezing (respiratory distress). These reactions usually resolve quickly without treatment. If a person has an immediate allergic reaction following their first COVID-19 vaccine, they should not have the second dose.

Serious reactions

Severe allergic reactions (anaphylaxis) within minutes to hours are very rare among people who have received COVID-19 vaccines.30,31 These adverse events typically occur within 15 minutes of administration. This is why after receiving a vaccine people should be asked to wait so that any serious reactions can be treated. Recent expert review by the TGA found no evidence of increased risk of anaphylaxis associated with the AstraZeneca vaccine above the expected rate for any other vaccine.32 Another study found that anaphylactic reactions to mRNA COVID-19 vaccines including the Pfizer vaccines is currently estimated to occur in only 2.5 to 11.1 cases per 1 million doses (0.025 percent of people, or 2.47 per 10,000 individuals), and largely among individuals with a history of allergy.33

Rare blood clots and COVID-19 vaccines

A very small number of people (approximately 4-6 people per million) who have received the Oxford/AstraZeneca vaccine have experienced blood clots with low platelet counts (thrombosis with thrombocytopenia).34-38 The figures suggest that while there is likely to be an association between the vaccine and development of blood clots, incidence is not greater than for the wider population.39 It is important for healthcare professionals and people who receive the vaccine to be aware of the very rare possibility of blood clots combined with low levels of blood platelets occurring within two weeks of vaccination particularly among people aged under 50 years. People who have been vaccinated should seek medical assistance immediately if they develop the following symptoms:40

  • shortness of breath
  • chest pain
  • swelling leg
  • persistent abdominal pain
  • neurological symptoms, including severe and persistent headaches or blurred vision
  • tiny blood spots under the skin beyond the site of injection


Monitoring the latest evidence about COVID-19 vaccines in Australia provides confirmatory evidence that the results of earlier trials and interim studies are accurate and that the benefits of receiving the COVID-19 vaccines outweigh the very small chance of experiencing an adverse reaction. Organisations and researchers in Australia and abroad are continually monitoring rollouts as they occur and even the most minor and likely to be unrelated reactions are being taken very seriously. As the Australian COVID-19 vaccine rollout continues, it is important that health professionals including nurses and midwives remain up to date and aware of the emerging evidence regarding the safety, efficacy, and effectiveness of vaccines. Patients, colleagues, family, and community members look to nurses and midwives for advice and guidance regarding their health, safety, and decisions regarding vaccination. It is vital that the most up to date and best available evidence is used to help inform them to make safe, beneficial decisions.


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Micah DJ Peters PhD and Casey Marnie are at the Australian Nursing and Midwifery Federation (ANMF) National Policy Research Unit (Federal Office), and the University of South Australia, Clinical and Health Sciences, Rosemary Bryant AO Research Centre

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