COVID-19 vaccine adverse events

The TGA and state and territory governments monitor COVID-19 vaccine safety. You must report any adverse events. Find out more about common and uncommon adverse events.

Reporting adverse events

Notify any adverse events after COVID-19 vaccination through the usual reporting mechanisms.

The TGA and state and territory governments will actively monitor COVID-19 vaccine safety.

Pfizer and Moderna COVID-19 vaccines – adverse events reported in clinical trials

Pfizer (Comirnaty)

Injection site reactions

In clinical trials of Pfizer COVID-19 vaccines, injection site reactions were very common (see Table 1). They were more common in adults than in children, and slightly more common in adults aged 55 years and under than in adults aged over 55 years.1

Severe pain was rare, and reported in <1% of participants aged 16 years and over in the initial phase II/III trial.1 In a later phase III trial, severe pain was reported in 1.5% of adolescents aged 12 to 15 years, compared with 3.5% in young adults aged 16 to 25 years.2

Local adverse events were generally milder in children aged 5 to 11 years than in the 16–25-year age group.3.

Injection site redness and swelling occurred in <10% of all participants. Local redness and swelling were more common (but still infrequent) in children aged 5 to 11 years than in people aged 16 to 25 years.3

These local reactions were generally mild to moderate, had a median onset of 1 to 2 days following vaccination, and resolved within 1 to 2 days of each dose.

Systemic adverse events

Most systemic adverse events were mild to moderate and did not affect daily activities. Systemic adverse events were more common after the second dose of Pfizer than the first dose in both adolescents and adults, and occurred at similar frequencies in children (see Table 1).1,2 They were generally milder and less frequent in older adults (>55 years) than in those aged 16 to 55 years.

The median onset of systemic adverse events in adults was 1 to 2 days after vaccination. Symptoms resolved in a median of 1 to 2 days.4

Systemic adverse events were generally milder and less frequent in adults aged over 55 years than in those aged 16 to 55 years. They also occurred at similar rates in people aged 12 to 15 years.2 Fatigue and headache were the most frequently reported systemic adverse events among children aged 5 to 11 years, adolescents aged 12 to 15 years and young adults aged 16 to 25 years (Table 1).2

Adverse events following booster

Adverse event rates after a booster dose in the Pfizer COVID-19 booster clinical trial were similar to rates following the second primary course dose of Pfizer. Both local and systemic adverse events after the booster (third) dose were mainly mild to moderate.5,6 The Pfizer bivalent vaccines as a booster dose had similar rates of adverse events to primary doses or first or second boosters of the Pfizer original vaccine (see Tables 1a and 1b).

In children aged 5 to 11 years, headache, muscle pain and use of antipyretic or pain medication were reported slightly more frequently after a booster dose than after dose 2.7

Table 1a: Frequency of select common adverse events reported within 7 days following each dose of Pfizer in the phase II/III trial 3,4,8

Adverse event 5 to 11 years of age, dose 1 5 to 11 years of age, dose 2 12 to 15 years of age, dose 1 12 to 15 years of age, dose 2 16 to 25 years of age, dose 1 16 to 25 years of age, dose 2 16 to 55 years of age, dose 1 16 to 55 years of age, dose 2 >55 years of age, dose 1 >55 years of age, dose 2
Injection site pain 74% 71% 86% 79% 83% 78% 83% 78% 71% 66%
Fever 3% 6.5% 10% 20% 7% 17% 4% 16% 1% 11%
Fatigue 34% 39% 60% 66% 60% 66% 47% 59% 23% 51%
Headache 22% 28% 55% 65% 54% 61% 42% 52% 25% 39%
Chills 5% 10% 28% 42% 25% 40% 14% 35% 6% 23%
Muscle pain 9% 12% 24% 32% 27% 41% 21% 37% 14% 28%
Joint pain 3% 5% 10% 16% 13% 22% 11% 22% 9% 19%
Required paracetamol     37% 51% 32% 46% 28% 45% 20% 38%

Table 1b: Frequency of select common adverse events reported within 7 days following each dose of Pfizer bivalent vaccine in adults9

Adverse event

Percentage of participants reporting event

Injection site pain

58%

Fatigue 

49%

Headache 

34%

Myalgia

22%

Uncommon adverse events

In the clinical trials, lymphadenopathy was reported in <1% of people aged 16 and older, in 0.8% of people aged 12-25, 0.9% of children aged 5-11, 0.1% of children aged 2-4 years and 0.2% of children aged 6-23 months.1

In the phase II/III study of children aged 5 to 11 years, safety data were reported up to 1 month after dose 2. There were 4 cases of rash (on the arm, torso, face, or body with no consistent pattern) in children aged 5 to 11 years. The rashes occurred more than 7 days after vaccination and were considered to be related to vaccination. Rashes were mild and self-limiting.8

There were 4 cases of Bell’s palsy (acute peripheral facial paralysis) in people who received the vaccine. However, this observed frequency was consistent with the expected background rate of Bell’s palsy in the general population. It may not have a causal relationship to vaccination.

Rare adverse events

The clinical trials for Pfizer COVID-19 vaccines were not powered to detect rare adverse events. From postlicensure data, rare adverse events associated with Pfizer vaccines include anaphylaxis (refer to Contraindications and precautions) and myopericarditis (refer to Myocarditis and pericarditis after mRNA COVID-19 vaccines).

Moderna (Spikevax)

In the phase III trial of Moderna COVID-19 vaccine, adverse reactions in the first 7 days after vaccination were very common in people aged 18 years and over. These reactions were generally mild to moderate and well tolerated.10 In the phase II/III trial of Moderna bivalent COVID-19 vaccine in people aged 18 years and over, adverse reactions were similar to the first or second booster of the Moderna original vaccine, and to the second dose of the primary series of the Moderna original vaccine.11

The adverse reaction profile of Moderna in adolescents aged 12 to 17 years was generally similar to that among young adult participants aged ≥18 years.12 

In children aged 6 to 11 years, 13 local and systemic adverse reactions occurred with similar frequencies to young adults aged 18 to 25 years. The exception was fever (including grade 3 fever), which was more common among 6-to-11-year-old children than young adults.13

The adverse reaction profile of Moderna 6 months to 5 years formulation was generally similar to that  in children aged 6 to 11 years, adolescents and young adults. The exception was fever (including grade 3 fever) after any dose, which was more common among children aged 6 months to 5 years than in adolescents and young adults. Fever was seen more frequently after dose 2 than dose 1 in this age group, although it was seen after both doses. The rate reported after dose 1 was also higher in infants and children aged 6 months to 5 years than in any other age group.14

Data from the preliminary clinical trials of Moderna and Pfizer vaccines in children aged 5 to 11 years indicate that short-term systemic adverse events (such as fatigue, headache, fever or nausea/vomiting) occurred more frequently in children enrolled in the Moderna trial. However, these trials used different methodologies and solicited different adverse events. Also, children who received placebo in the Moderna trial reported adverse events more frequently than children in the Pfizer trial. No data are available that directly compare the Moderna vaccine with the paediatric Pfizer vaccine in children aged 6 to 11 years or in infants and young children aged 6 months to 5 years.

Local adverse events

Adverse reactions at the injection site were very common after both doses of Moderna COVID-19 vaccine in all age groups (see Table 2). Injection site pain was the most common adverse event reported after both doses in all age groups Injection site pain was also the most common local adverse event reported in infants and children 6 months to 5 years, but it was reported less frequently than in other age groups (see Table 2).12,14  

Most local adverse reactions were grade 1 (did not interfere with activities) or grade 2 (interfered with activities or required repeated use of over-the-counter pain relief) in severity. The proportion of grade 2 reactions was higher after the second than the first dose. Most local adverse reactions occurred within 1 to 2 days of vaccination and resolved within 2 to 3 days of a dose.14

Delayed-onset injection site reactions that started after the first 7 days, including pain, redness or swelling, occurred in 0.8% of adults after the first dose, and 0.2% after the second dose. These reactions resolved after a mean of 4 to 5 days.10

Axillary or groin lymphadenopathy (swelling of the lymph nodes) within 7 days of vaccination was a solicited adverse event in the Moderna vaccine trials. It occurred in 10% of vaccine recipients aged 18 years and over after the first dose and 14% after the second dose. It was more common in adolescents aged 12 to 17 years, occurring in 23% (first dose) and 21% (second dose) of recipients. Lymphadenopathy was also common in children aged 6 to 11 years, occurring in 15.5% (first dose) and 18% (second dose). It was less common in infants aged 6 to 23 months, occurring in 6% (first dose) and 9% (second dose); and in young children aged 2 to 5 years, occurring in 7% (first dose) and 9% (second dose). However, lymphadenopathy was slightly more common in children aged 6 months to 5 years who had a previous SARS-CoV-2 infection (7.4% to 10.9%) than in children who did not have a previous SARS-CoV-2 infection (5.6% to 9.5%) before vaccination.14

Systemic adverse events

Systemic adverse reactions were more frequent after the second (79%) than the first dose (55%) of Moderna COVID-19 vaccine, and were more common in participants aged under 65 years than in those aged 65 years or over (Table 2).

In participants aged 2 years and older, the most commonly reported systemic reactions were fatigue, headache and myalgia.14 In infants and toddlers aged 6 to 36 months, the most commonly reported systemic reactions were irritability/crying, sleepiness and loss of appetite.14 The majority of systemic reactions were grade 1 (did not interfere with activities) or 2 (interfered with activities or required repeated use of over-the-counter pain relief) in severity. The proportion of grade 2 and grade 3 (prevented daily activities or required use of prescription pain relief) systemic reactions were higher after dose 2 than dose 1. Most systemic adverse reactions occurred within 1 to 3 days of vaccination and resolved within 2 to 3 days of a dose.15

Fever rates after dose 2 were high for most age groups. Relative to other ages, children aged 6 months to 5 years had higher rates of fever overall when considering rates of fever after both dose 1 and dose 2. Most fevers occurred within 2 days of vaccination, with 1 in 3 children who received the vaccine requiring anti-pyretic medication, although the duration was short (median 1 day). Additionally, children who had previously had SARS-CoV-2 infection were more likely to have a fever than those who had not previously had SARS-CoV-2 infection.14

Table 2a: Frequency of select common adverse events reported within 7 days following each dose of Moderna in the phase III trial10,12

Adverse event 37 months to 5 years of age, dose 1 37 months to 5 years of age, dose 2 6 to 11 years of age, dose 2 6 to 11 years of age, dose 2 12 to 17 years of age, dose 1 12 to 17 years of age, dose 2 18 to 64 years of age, dose 1 >18 to 64 years of age, dose 2 >≥65 years of age, dose 1 ≥65 years of age, dose 2
Injection site pain 61%a 71%a 93% 95% 93% 92% 87% 90% 74% 83%
Lymph node swelling at the axilla 7%a 9%a 16% 18% 23% 21% 12% 16% 6% 9%
Fever 8% 16% 3% 24% 3% 12% 0.9% 17% 0.3% 10%
Fatigue 40% 48% 43% 64% 48% 68% 38% 68% 33% 58%
Headache 12% 16% 31% 54% 45% 70% 35% 63% 25% 46%
Chills 6% 12% 10% 30% 18% 43% 9% 49% 5% 31%
Myalgia 10% 16% 15% 28% 27% 47% 24% 62% 20% 47%
Arthralgia 6% 9% 9% 16% 15% 29% 17% 46% 16% 35%
Nausea/vomiting 7% 10% 11% 24% 10% 18% 9% 21% 5% 12%
  • a. Frequencies of local reactions of injection site pain and lymph node swelling at the axilla in the 37-month to 5-year columns are for the entire 2-to-5-year age cohort.

Table 2b: Frequency of select common adverse events reported within 7 days following each dose of Moderna in the phase II/III trial in infants and very young children14

Adverse event 6 to 23 months of age, dose 1 6 to 23 months of age, dose 2 24 to 36 months of age, dose 1 24 to 36 months of age, dose 2
Injection site pain 37% 46% 61%a 71%a
Lymph node swelling at the axilla 6% 9% 7%a 9%a
Fever 11% 15% 11% 19%
Irritability/crying 68% 64% 55% 54%
Sleepiness 37% 35% 30% 36%
Loss of appetite 30% 32% 24% 31%
Use of anti-pyretic or pain medication 28% 34% 20% 30%
  • a. Frequencies of local reactions of injection site pain and lymph node swelling at the axilla in the 24-to-36-month columns are for the entire 2-to-5-year age cohort.

Adverse events following booster

In a clinical trial using Moderna COVID-19 original vaccine as a booster dose (using a dose of 50 micrograms), adverse events were generally mild to moderate, and similar to rates seen after the primary 2-dose series in phase II and III trials.15 The Moderna bivalent vaccine as a booster dose had similar rates of adverse events to the first or second booster of the Moderna original vaccine, and to the second dose of the primary series of the Moderna original vaccine.11

Table 3: Frequency of select common adverse events reported within 7 days following each dose of Moderna bivalent vaccine in the phase II/III trial in adults11

Adverse event

Moderna bivalent vaccine

Injection site pain

77%

Swelling

7%

Fever

4%

Fatigue 

55%

Headache 

44%

Chills

24%

Myalgia

40%

Arthralgia

31%

Nausea/vomiting

10%

Uncommon adverse events

Lymphadenopathy occurred in 1.1% of adult vaccine recipients, 4.3% of adolescent vaccine recipients and 0.4% of adolescent placebo recipients aged 12 to 17 years overall. It was less common overall in children aged 6 to 11 years (1.9% of Moderna recipients), young children aged 2 to 5 years (0.9% of Moderna recipients) and in infants aged 6 to 23 months (1.5% of Moderna recipients).14 Most lymphadenopathy was mild to moderate and resolved within 1 to 2 days. 

Hypersensitivity-related adverse reactions were slightly more common in people who had the vaccine than in people who had the placebo among adults (1.5% versus 1.1%) and among children aged 2 to 5 years (3.5% versus 2.5%), but not infants aged 6 to 23 months (3.9% versus 5.3%).14 These reported anaphylactic or severe hypersensitivity reactions did not occur in close timing with the vaccine. There were no events clinically concerning for anaphylaxis in the 6-month to 5-year age group within the trial. The rates of occurrence of these reactions among children aged 6 to 11 years are currently unknown, as this vaccine has not yet been used at a population level.

There was a small imbalance in the number of participants with Bell’s palsy (3 in the vaccine arm on day 22, 28 and 32, compared with 1 in the placebo arm on day 17). All cases were judged as unrelated to the administration of either the vaccine or placebo. Two participants, both with a history of facial dermal filler cosmetic injection, experienced facial swelling within 2 days of receiving the vaccine.

Young children may rarely experience febrile convulsions (also called febrile seizures) after vaccination. One vaccine-related febrile convulsion was reported during the trial in children aged 6 months to 5 years. This occurred in a 17-month-old female child, one day after dose 1. There were 2 non-febrile seizures reported in vaccine recipients aged 2 to 5 years, which were considered not related to vaccination. Children with a history of febrile convulsions were excluded from participating in this trial, therefore the rate of potential febrile convulsions in this group is unknown.14

Pfizer and Moderna COVID-19 vaccines – adverse events reported in post-licensure use

Post-licensure surveillance is undertaken for all vaccines to identify signals for rare, population-specific events.

Reactogenicity

Injection site pain and systemic adverse events such as fatigue, headache and muscle ache following Pfizer have been commonly reported in routine use at similar or lower rates than reported in clinical trials. A small proportion of individuals have reported missing work, study or routine term duties for a short period following vaccination with Pfizer (6.7% following dose 1 and 21.2% following dose 2).16

Data on booster doses from the V-safe and Vaccine Adverse Event Reporting Systems (VAERS) show no unexpected patterns of adverse events.17,18 These data mainly involve the same mRNA vaccine as the primary course given as a booster dose. For Pfizer, local and systemic reactions were reported less frequently after dose 3 than dose 2. For Moderna, local reactions were reported slightly more frequently and systemic reactions slightly less frequently after dose 3 than dose 2.

Myocarditis and pericarditis

Myocarditis and pericarditis have been reported very rarely in people vaccinated with Pfizer and Moderna vaccines.19-23  New data from the United Kingdom indicate an increased risk of myocarditis or pericarditis after receiving AstraZeneca vaccine, but this risk is smaller than for mRNA vaccines. Myocarditis and/or pericarditis can occur after Novavax. A small number of cases of myocarditis and pericarditis have been reported in the clinical trial and in Australia. The TGA assessed these Australian cases as likely vaccine-related. The risk of myocarditis or pericarditis after receiving Novavax vaccine is not yet known. Myocarditis and pericarditis can also occur following COVID-19 disease. Post-COVID-19 condition (’long COVID’) is also associated with cardiovascular complications.24

Data from Canada, Israel, Australia, the United Kingdom, the United States and some European countries suggest that the incidence of myocarditis and pericarditis associated with Moderna is higher than with Pfizer. The severity of cases does not appear to differ.  Evidence from Canada suggests that an extended interval of 8 weeks between dose 1 and dose 2 may reduce the risk of myocarditis and/or pericarditis.

For detailed information on myocarditis and pericarditis refer to the ATAGI Guidance on myocarditis and pericarditis after COVID-19 vaccine.

Pfizer and Moderna COVID-19 vaccines – safety and adverse events in pregnancy

In a prospective cohort study of more than 35,000 pregnant women who received an mRNA COVID-19 vaccine (54% received Pfizer, 46% received Moderna), the adverse event profile was similar to that of non-pregnant women.25,26 Pregnant women were slightly more likely to report injection site pain, and less likely to report generalised symptoms such as fever or tiredness. Fever of 38°C or above was reported by less than 1% of pregnant women after the first dose of Pfizer or Moderna, less than 5% after the second dose of Pfizer, and less than 12% after the second dose of Moderna. Fever of 39°C occurred in <0.05% of pregnant participants after the first dose, and 0.5% after the second dose. The findings from this large study are supported by other smaller observational studies.25-27

Pregnancy outcomes after vaccination

The same study reported on pregnancy and neonatal outcomes in 827 women who received an mRNA COVID-19 vaccine in pregnancy. The study did not identify any safety concerns.28 Complications such as preterm delivery, stillbirth, small for gestational age infants and congenital anomalies occurred at a similar rate to what is seen in the general population.

In the clinical trial for the Pfizer COVID-19 vaccine, 23 women became pregnant during the study period, of which 11 had received Pfizer.29  In the clinical trial for the Moderna COVID-19 vaccine, 13 women were unknowingly pregnant or became pregnant during the trial, of which 6 received the vaccine.30 Information about the outcomes of their pregnancies is awaited.

Animal studies of Pfizer and Moderna COVID-19 vaccines have not shown any negative effects on fertility or pregnancy.30-33

A phase II/III randomised controlled trial of Pfizer in pregnant women is underway in the United States.34

AstraZeneca (Vaxzevria)

In the phase II/III trials of the AstraZeneca COVID-19 vaccine, adverse events reported within 7 days following vaccination were very common, but the majority were mild or moderate.35

The safety profile was consistent across participants whether or not they had serological evidence of previous SARS-CoV-2 infection.

Local and systemic adverse events

The most common local adverse events were injection site tenderness and pain.

The most common systemic adverse events were fatigue and headache35 (see Table 4).

Local or systemic solicited adverse events were most commonly reported on day 1 after vaccination. These reactions were generally mild to moderate, and resolved within a few days.

Adults aged ≥65 years reported fewer local or systemic solicited adverse events, and fewer ≥grade 3 solicited adverse events, than younger adults.1,35 Most adverse events did not affect daily activities.

Adverse events reported after the second dose were milder and less frequent than those after the first dose. 

Reports on unsolicited adverse events were collected through to 28 days after a dose of AstraZeneca. Most of the unsolicited adverse events were mild to moderate in severity and consistent with adverse events commonly observed after vaccination with other vaccines.35

Table 4: Frequency of selected common adverse events reported within 7 days following at least 1 dose of AstraZeneca in a phase II/III trial in people aged >18 years36

Adverse event 18 to 55 years of age, dose 1 18 to 55 years of age, dose 2 56 to 69 years of age, dose 1 56 to 69 years of age, dose 2 ≥70 years, dose 1 ≥70 years, dose 2
Injection site pain 61% 49% 43% 34% 20% 10%
Injection site tenderness 76% 61% 67% 59% 49%

 

47%

 

Fatigue 76% 55% 50% 41% 41% 33%
Headache 65% 31% 50% 34% 41% 20%
Muscle pain 53% 35% 37% 24% 18% 18%
Fever 24% 0% 0% 0% 0% 0%

Adverse events following booster

A third dose of AstraZeneca COVID-19 vaccine after two previous doses of AstraZeneca was well tolerated and associated with lower adverse event rates than after the primary vaccine doses.37

Rare adverse events

In a combined interim analysis of 4 clinical trials, one case of transverse myelitis was reported in the vaccine arm. This occurred 14 days after dose 2.38 An independent neurological committee reviewed the case and the likely diagnosis was idiopathic short segment spinal cord demyelination.

Two additional cases of transverse myelitis were considered unlikely to be related to vaccination, with one case subsequently attributed to pre-existing but previously unrecognised multiple sclerosis. The other case was reported in the control group.

Anaphylaxis after AstraZeneca has been reported rarely. See Contraindications and precautions – clinical guidance for more details.

Adverse events identified in post-licensure use

Reactogenicity 

Systemic events such as fatigue, headache and muscle ache, along with injection site pain, are common after receiving AstraZeneca. These events occur at similar rates to those reported in clinical trials. A small proportion of people have reported missing work, study or routine duties for a short period after vaccination with AstraZeneca (17.6% after dose 1 and 5.3% after dose 2).16 Updated data, based on surveys of millions of Australian vaccine recipients, are regularly published by AusVaxSafety.  

Immune (idiopathic) thrombocytopenic purpura (ITP)

ITP has been reported following AstraZeneca COVID-19 vaccine. In Australia, the observed incidence of ITP after AstraZeneca was found to be 8 per million doses, twice the expected background rate of 4.1 per million.39 One fatal case in Australia has been causally linked to vaccination.40 One study from Scotland suggested an association between AstraZeneca and ITP with an estimated risk of 1.13 cases per 100,000 doses.41

People should seek medical attention if they experience unusual bruising, petechiae or bleeding. People who develop ITP within 42 days after receiving AstraZeneca should consult a haematologist about whether to proceed with the second dose using the same or an alternative vaccine, and the timing of the second dose.42

Reported events under investigation 

Medical events may be reported after vaccination but may not be causally related to the vaccine. Investigation and causality assessment is required to assess these reports. The conditions described below have been reported after vaccination, but a causal relationship with the vaccine has not been established. 

Capillary leak syndrome 

Capillary leak syndrome has been reported rarely following AstraZeneca in the United Kingdom and Europe,42 including in people with a history of capillary leak syndrome. One case has been reported in Australia, but a causal link with the vaccine could not be established.43 Capillary leak syndrome is a rare but severe relapsing-remitting condition where capillary fluid leaks into surrounding tissues. 

AstraZeneca is contraindicated in people with a history of capillary leak syndrome. 

Guillain–Barré syndrome

Cases of Guillain–Barré syndrome (GBS) have been reported following AstraZeneca. GBS is a rare immune disorder that often follows a viral infection.44-48The European Medicines Agency concluded that a relationship with AstraZeneca could be possible.

Myocarditis and pericarditis

 A study from the United Kingdom in December 2021 found an increased risk of myocarditis and pericarditis associated with the AstraZeneca vaccine. The risk was observed for males and females for any dose. The risk was highest in men aged under 40 years, 8 to 14 days after dose 2 (estimated excess of 14 cases per million doses, 95% CI 8–17.49 Yellow Card reports from the United Kingdom also indicate a risk associated with AstraZeneca, with rates reported in young adults aged 18 to 29 years of 10 per million doses after dose 1 and 16 per million doses after dose 2.50

However, the risk of myocarditis and pericarditis after AstraZeneca remains smaller than that for mRNA vaccines. In similar age groups from the same reporting system, the rate for Pfizer vaccine after dose 2 was 27 per million doses and 70 per million doses after a second dose of Moderna.50 No data are available on the rate of myocarditis and/or pericarditis following AstraZeneca in Australia.

Thrombosis with thrombocytopenia syndrome (TTS)

Thrombosis with thrombocytopenia syndrome (TTS) is a rare condition that has been reported after AstraZeneca. TTS has occurred in several countries, including Australia. It appears to be causally linked to vaccination.51

For detailed information refer to the Joint statement from ATAGI and THANZ on Thrombosis with Thrombocytopenia Syndrome (TTS) and the use of COVID-19 Vaccine AstraZeneca.

Nuvaxovid (Novavax)

In the phase II/III trials of Novavax, adverse events within 7 days of vaccination were very common in people aged 18 years and older. Most were generally mild to moderate and well tolerated.

Preliminary data on the safety of Novavax in adolescents aged 12 to 17 years are available from the ongoing phase III trial. The adverse reaction profile was generally similar to that among adult participants aged 18 years and older. The exception was fever (including grade 3 fever), which was more common among adolescents aged 12 to 17 years than among adults. The frequency of local and systemic reactions was generally similar among participants aged 12 to 14 years and those aged 15 to 17 years.52

There were no substantive differences in the frequency of adverse events overall observed in the clinical trial by sex, race, ethnicity, medical comorbidities or baseline SARS-CoV-2 status.

Local adverse events

Local adverse events were very common, particularly after dose 2, in both adolescents (76%) and adults (79%) (see Table 5). Injection site tenderness and pain were the most common adverse events reported after both dose 1 and dose 2. Local adverse events were more frequent among younger participants (age 18 to 64 years) than in older participants.

Most local adverse reactions were grade 1 (did not interfere with activities) or grade 2 (interfered with activities, or required repeated use of over-the-counter pain relief) in severity. Grade 3 events (interfered basic activities like eat or get dressed, may also require medical attention) were uncommon and the proportion of grade 3 reactions was higher after the second than the first dose. The median duration of injection site reactions was 2 days or less after any dose.52

Systemic adverse events

Systemic adverse events were reported in 47.7% of Novavax COVID-19 vaccine recipients after dose 1, and 69.5% after dose 2 in people aged 18 years and older.53 In adolescents aged 12 to 17 years, systemic adverse events were reported in 55% of Novavax COVID-19 vaccine recipients after dose 1, and 75% after dose 2. The most common solicited systemic adverse events were headache, myalgia, fatigue and malaise. Systemic adverse events were more frequently reported after dose 2, and in younger people aged 12 to 17 years than in adults aged 18 years and older (Table 5).52,54

Fever was more common in adolescents aged 12 to 17 years, with 1% of adolescents reporting fever after the first dose, and 17% after the second dose (2% Grade 3). This is compared with 0.4% of adults after first dose and 6% of adults after second dose (0.4% Grade 3).52,54

Most systemic adverse reactions were grade 1 (did not interfere with activities) or grade 2 (interfered with activities, or required repeated use of over-the-counter pain relief) in severity. Grade 3 events (interfered basic activities like eat or get dressed, may also require medical attention) were uncommon. In adolescents aged 12 to 17 years, there was only one correctly recorded grade 4 event (required medical intervention, or required hospitalisation), which was a case of headache following dose 2 in a Novavax COVID-19 vaccine recipient. The median duration of systemic adverse events was 1 to 2 days after any dose.52,54

Table 5: Frequency of select common adverse events reported within 7 days following each dose of Novavax in the phase III trial52,54-56

 

Adverse event 12 to 17 years of age, dose 1 12 to 17 years of age, dose 2 ≥18 years of age, dose 1 ≥18 years of age, dose 2
Injection site pain 45% 61% 31% 

 

45–52%
Injection site tenderness 56% 65% 45–58% 62–76%
Erythema 4% 15% 1–5% 4–10%
Swelling 5% 17% 1–2% 4–9%
Fever 1% 17% 0–3% 3–5%
Fatigue 24% 50% 20–22% 40–41%
Headache 30% 57% 21–25% 39%
Malaise 15% 40% 12–17% 26–38%
Myalgia 34% 49% 21% 39%
Arthralgia 7% 16% 5–6% 18–19%
Nausea/vomiting 8% 20% 4–5% 10%

Uncommon and rare adverse events

There was a numerical imbalance in the reported incidence of hypertension in older adults during the 3 days following vaccination (1% in Novavax COVID-19 vaccine recipients and 0.6% in placebo recipients).53 Hypertension was not reported in the adolescent population in the clinical study.52

Potential immune-mediated medical conditions were numerically higher in the Nuvaxovid group than in the placebo group in participants 18 to 64 years of age but numerically lower in the Nuvaxovid than in the placebo group in participants older than or equal to 65 years of age. There were no potential immune mediated medical conditions reported in adolescents aged 12 to 17 years which were considered related to vaccination. Lymphadenopathy was uncommon in both adolescents and adults (experienced by less than 1 in 100 participants).54

Myocarditis and/or pericarditis can occur after Novavax. Cases of myocarditis and pericarditis following Novavax have been reported in clinical trials and in Australia.57

A total of three cases of myocarditis were reported in the two phase III trials.55,56 Of these, two occurred in the vaccine group and one in the placebo group.53 Of the two cases in the vaccine group, one was a young healthy participant with onset 3 days after dose 2, and the other was a participant aged over 65 years. There is currently no published additional information on these cases and these cases are not necessarily attributable to the vaccine.

Up to 30 June 2022, 3 cases of myocarditis and 12 cases of pericarditis from 160,000 doses administered in Australia had been reported to the TGA and were assessed as being likely to be vaccine-related. The small number of total doses given globally prevents the calculation of a precise risk at this time. ATAGI will continue to monitor data as it emerges and update advice accordingly.

It is recommended that all COVID-19 vaccine recipients should be aware of the potential signs and symptoms of myocarditis or pericarditis, and should be counselled about when to seek medical attention. For more information, see ATAGI guidance on myocarditis and pericarditis.

 

Adverse events identified in post-licensure use

There are limited data on post-licensure use of the Novavax vaccine. ATAGI will continue to monitor and evaluate evidence on the safety of Novavax vaccine as it emerges.

Further reading

  1. Polack FP, Thomas SJ, Kitchin N, et al. Safety and efficacy of the BNT162b2 mRNA COVID-19 vaccine. New England Journal of Medicine 2020;383:2603-15.
  2. Frenck RW, Jr., Klein NP, Kitchin N, et al. Safety, immunogenicity, and efficacy of the BNT162b2 Covid-19 vaccine in adolescents. New England Journal of Medicine 2021;385:239-50.
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