Summary of Adverse Drug Reaction reports in Sweden with Pandemrix received through December 4

Monday, December 14, 2009

Almost 4 million individuals in Sweden have been vaccinated as of December 4. In total, the Medical Products Agency has received close to 3000 adverse event reports from Health Care Professionals and from consumers. The reporting pattern is generally consistent with what has been seen from previous clinical trials, with the exception of allergic and neurological reactions. In view of the great number of vaccinated individuals in Sweden and the limited number of adverse drug reaction reports and their pattern, the conclusion is that the safety of the vaccine in use is satisfactory.

Almost 5.3 million adult doses of Pandemrix have been delivered to the public medical service and according to data from the Swedish Institute for Infectious Disease Control (SMI) by December 4 approximately 4 million individuals have been vaccinated. The Medical Products Agency has continuously published summaries of adverse events reported with Pandemrix. The summaries focus on reports relating to previously unknown or suspected serious side effects while the known adverse and mild events are reported only briefly.

In addition, this summary specifically addresses reports from Health Care Professionals on allergic reactions, neurological reactions, reactions in children and in pregnant women, rejection after organ transplant, deaths and lack of efficacy of vaccination. The duration of some of the common expected reactions are also described as well as an overview of adverse events reported directly from consumers.

Reports from Health care Professionals

Almost 1200 reports have been received from Health Care Professionals.  The majority of the adverse events reported are expected and known reactions such as injection site reactions and influenza like symptoms.

Comments on certain types of reactions

The duration of expected reactions

The duration of the most common expected reactions of Pandemrix which have been reported are described below:

  • Local symptoms related to injection site, such as swelling, redness and pain in the vaccinated arm were noted primarily to resolve within a few days of vaccination, but has to a small extent of the reported cases been lasting from 1-2 weeks.  
  • Symptoms related to influenza-like illness, such as headache, fever, nausea, were noted also to resolve within a few days of vaccination.  However, in small number of cases, the symptoms were noted to last up to 5-7 days after vaccination.  
  • Among the reports with generalized symptoms of fatigue, muscle and joint aches there are some that describe duration of 10 days to 2 weeks after vaccination.

Allergic reactions

Until December 4, a total of 426 reports of allergic reactions have been received from health care providers. These reactions have occurred in 371 patients shortly after vaccination with Pandemrix. In cases deemed serious, the patients needed treatment with antihistamines, adrenaline and cortisone and in some cases also supervision in emergency room/hospital. In all cases, the hypersensitivity reactions resolved completely within a short time.

Previously three cases of anaphylactic shock have been reported in association with the vaccination of patients with known egg allergy; hypersensitivity/allergy to various food, including nuts, and in one case with no previous history of allergy reported. A fourth report concerns a 10-year old girl without previous known allergy and where the anaphylactic reaction was cured within short time.

Allergic/anaphylactic reactions have hitherto been reported in 15 patients with known egg allergy and in 37 patients with reported allergy to other substances such as pollen, grass, drugs, nuts, peanuts, fruit, fish or furred animals, etc.

Similar allergic reactions have also been reported in other countries in Europe and has resulted in an update of the product information (SPC/PL) for Pandemrix.

Neurological reactions 

During the last period, from November 20 to December 4, a total of 157 neurologic adverse events have been reported of which 26 were assessed as serious. The most common reactions reported continue to be dizziness, headache, fainting and paresthesia. Two new reports with facial palsy were deemed to have a possible relationship to the vaccination.

Hitherto a total of 23 reactions with convulsion / epilepsy have been described. Twenty of these have occurred in patients younger than 18 years of age. An evaluation of the cases with serious neurological reactions is ongoing including a follow up on the cases previously described. Even though these reactions are rare they will still be focused on in the forthcoming evaluation.

Reactions in children

As of December 4, at least 102 000 children younger than 3 years, and about 450 000 children aged 3 years up to 13 years, have been vaccinated in Sweden. This estimate is based on data from the Swedish Institute for Infectious Disease Control (SMI).

Through December 4, 242 a total of reports with 385 serious reactions have been received from Health Care Professionals. Of these cases 86 events occurred in children (0-17 years of age).

The most common adverse events in children, reported from Health Care Professionals, are neurological and immunological reactions or general symptoms, as in the previous summary.

Among the serious reactions described in children are neurological symptoms as convulsions (most common), epilepsy, febrile convulsion and dizziness. Two cases of facial palsy have also been reported.

Since the last summary another 4 cases of anaphylactic reactions and two cases of anaphylactic shock have been reported. All of them have recovered. In addition, few cases of previously reported reactions such as urticaria and respiratory disorder have been reported as well as a case of arthritis.

A fatal case in a child (aged 1 year) and a case in an adolescent 17 year old with rejection of a transplanted kidney have been reported since the last report. 


Reactions in pregnant women

As of December 4, based on data from the Swedish Institute for Infectious Disease Control (SMI), more than 31 000 pregnant women are vaccinated with Pandemrix. A total of 22 reports of suspected adverse reactions which have occurred in connection to vaccination have been received from Health Care Professionals. The pattern of adverse events is similar to what has been observed before and no new or remarkable events are seen.

In 6 women spontaneous abortions occurred in temporal association with vaccination with Pandemrix and in one woman, intrauterine foetal death (gestational age week 24) occurred two days after vaccination. 

As yet another case of intrauterine foetal death occurred in a pregnant women in week 41, 5 days after vaccination. The case is still under investigation. In the light of the fact that a large number of pregnant women have been vaccinated there is no reason to believe that the vaccine has caused termination of pregnancies. Miscarriages occur rather frequently and the frequency of intrauterine foetal deaths (> 28 weeks) has been shown statistically to be about 300 cases per year in Sweden.

Rejection of transplanted organs

Two cases have been reported, one death after rejection of a heart transplant in a 67 year old man and a rejection of a transplanted kidney in a 17 year old girl. In the first case the vaccination may have contributed by triggering the rejection which probably was caused by insufficient immunosuppressive treatment. In the second case it is not clear whether the rejection reaction was a spontaneous event or if the vaccination has contributed to the outcome.

No other cases have been reported, neither in Sweden nor in other countries within Europe. This has lead to a recommendation (3 December 2009) that emphasize that an adequate immunosuppressive treatment should be verified bore vaccination of organ transplanted patients.

Deaths reported

As of December 4, a total of 18 deaths have been reported, of which 6 are new reports since the previous summary published November 26. In this summary only the new cases are commented.

Four of the new cases involve elderly patients (94, 91, 90 and 82 years). All of these patients had concomitant chronic disease, which most likely have contributed to the fatal outcome.  From what has emerged so far, there is no information that confirms a causal association between the vaccination and the deaths.

Two of the new cases concerns younger patients (36 and 1 year, respectively).

One of the patients (36 years of age) was found dead in his home the day after the vaccination. No clinical explanation to the death occurred. The case is under investigation. 

The other case involves a 1 year old child with severe lung- and heart disease which was known before the vaccination. The day after the vaccination the condition of the patient worsened and was admitted to Emergency Ward. The child was diagnosed with sepsis and respiratory distress. The condition of the patient became even worse and the child died of heart failure. According to the report there was no direct suspicion that the vaccination has contributed to the course and the death.

Lack of efficacy after vaccination

In 9 cases there have been reports of lack of efficacy after vaccination with Pandemrix, cases where the vaccinated person have received influenza. Four adult individuals fell ill 5 days to 4 weeks after vaccination. Three of the patients had chronic underlying diseases. Five were children (4-13 years of age) and two of these had an underlying disease. The children fell ill 4-20 days after the vaccination and one child with asthma had influenza with very severe respiratory distress.

The time for incubation of influenza A(H1N1) is normally 3 days – but may vary (1-7 days). It is most likely that the person has already been infected in those cases where a short time has elapsed between the vaccination and falling ill. In light of the large amount of vaccinated individuals and the large extent to which the influenza has been spread these few reports indicate that the vaccine is efficient. Pandemrix cannot cause H1N1 infection since it is a split inactivated vaccine and without any viral infectious activity.

Experience from consumer reporting

Since the vaccination campaign with Pandemrix began in Sweden on October 12, about 1800 consumer reports of suspected adverse reactions have been received by the Medical Products Agency. 440 reports have been received since the last published summary. About 30 of these 440 reports include events that have been classified as serious and about 100 of the reports concern children (0–17 years).

Among the serious events recently reported there are cases describing coxitis (1 case), inflammation in tendinitis/bursitis in the shoulder of the vaccinated arm (2 cases), early spontaneous miscarriages (3 cases), hallucinations /disorientation confusion in three cases of which one with fever.

Three reports describe reduction of body temperature during the night after the vaccination and two cases of herpes zoster related illness. The reported non-serious reactions are as previously, mainly flu-like symptoms, local reactions at the injection site (the arm) which in some cases have hindered common domestic duties, and different types of allergic symptoms.

In spite of that the majority of the reports do not include serious reactions it is clear from the descriptions that in many cases it has caused severe pains and other inconveniences for several days.



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