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This application is a service of the Singapore Government.

Health Sciences Authority

About HSA Regulatory Review on Influenza A H1N1 Vaccines

See MOH press release here

  1. Currently, clinical trials to establish the safety and efficacy of H1N1 vaccines are still ongoing and limited safety data is just becoming available in September 2009.
  2. Due to the urgent need to produce H1N1 vaccines quickly to meet the demands of the pandemic, drug regulatory authorities around the world have developed mechanisms for expediting the review of pandemic vaccines.  In Singapore, the Health Sciences Authority (HSA) employs a similar approach of a 'rolling review' submission of pandemic vaccines.  This allows vaccine manufacturers to submit data sets for regulatory review as and when they become available, without having to wait until all the data is ready before submission to the authority, as is the case for products reviewed under normal circumstances.
  3. Based on available scientific data, HSA will advise MOH on the safety and efficacy of the vaccine.
  4. Like all health products, no vaccine can be guaranteed to be 100 per cent safe.  However, initial data available for the H1N1 vaccines and experience with other similar influenza vaccines suggest that these vaccines have a relatively good safety profile.  Some serious adverse events related to this class of vaccines have been reported in the past but these have been rare.  The common side effects associated with these vaccines include pain at the site of injection, fever, headache, muscle aches and pains.  In rare circumstances, some patients may experience severe allergic reactions such as swelling and difficulty in breathing and swallowing, and adverse effects affecting the neuromuscular system such as Guillain Barre Syndrome (gradual paralysis and generalised loss of reflexes).
  5. As H1N1 vaccines may be used in a very large number of patients during a pandemic, certain adverse events which are too rare to show up in clinical trials may become apparent when a significant number of patients are given the vaccines.  However, given the safety record of seasonal flu vaccines, such events are likely to be rare.
  6. To address these safety concerns, the World Health Organisation has advised all countries who are considering administering the pandemic vaccines to conduct intensive monitoring for safety.  In line with this, HSA will be intensifying its safety surveillance activities to closely monitor the safety of the pandemic vaccines as they are used, so that rapid action can be taken to safeguard the health and safety of the public if this becomes necessary.