Recognised safety profile of flu antivirals and vaccines confirmed

No unexpected new safety issues have been identified from Yellow Card reports.

Article date: February 2010

This article updates you on reports of suspected adverse reactions received up to Jan 19, 2010 for the antiviral medicines and vaccines in use to help manage swine flu.

You can still report suspected adverse reactions to these medicines and vaccines at {Yellow Card](

Swine flu - Report a side effect with a flu medicine

Image of patient information graphic about reporting side effects to swine flu medicines and vaccines.

Pandemic vaccines

Celvapan and Pandemrix are the swine flu H1N1 vaccines in use in the UK. As of Jan 17, 2010, more than 4 million doses of these vaccines (mostly Pandemrix) have been given in the UK, including at least 132 000 in pregnant women. Up to and including Jan 19, 2010, we have received a total of 2817 UK reports of suspected ADRs to the H1N1 vaccines. The 2817 reports include a total of 7487 suspected reactions.

No unexpected new safety issues have been identified from reports received to date. The balance of benefits and risks for Celvapan and Pandemrix remains positive. Most reports received are for Pandemrix (87%, n=2451), which is likely be due to higher use of this vaccine in the UK.

The total number and the nature of suspected adverse effects reported are very much as we expected at this stage in the immunisation campaign. The most frequently reported suspected adverse effects are injection site reactions (eg, pain, swelling, redness), or are well established adverse effects of many vaccines, including the swine flu vaccines (eg, nausea, vomiting, dizziness, muscle pain, fever, fatigue, headache, swollen glands, flu-like illness). In general, these are neither serious nor long-lasting. For the isolated cases of other medical conditions reported, the available evidence does not suggest that the vaccine caused the condition and these may have been coincidental events.

Seven cases of suspected Guillain Barre syndrome (GBS) have been reported in the UK up to Jan 12, 2010. There is currently no evidence across Europe that H1N1 vaccines cause GBS or other similar neurological conditions and these were most likely to be coincidental events.

18 deaths, including three cases of intrauterine death, following Pandemrix have been reported in the UK up to Jan 19, 2010. There is currently no suggestion that the vaccine contributed to any of these deaths. Following analyses of the expected numbers of (background) adverse events in pregnancy relative to the number of pregnant women immunised, there remains no evidence of any risks to pregnancy due to the vaccine.

Oseltamivir and zanamivir

Up to and including Jan 19, 2010, MHRA has received a total of 1061 reports (including 1908 suspected adverse reactions) for oseltamivir and 34 reports (including 62 suspected adverse reactions) for zanamivir.

There have been at least 1 125 627 treatment courses of oseltamivir and 14 558 treatment courses of zanamivir between July 23, 2009 and Jan 12, 2010.

The balance of risks and benefits for oseltamivir and zanamivir within their licensed indications remains positive, and no new safety issues have been identified. There remains no evidence to suggest that they carry any risks to pregnancy. The most common suspected reactions are consistent with the signs and symptoms of flu-like illness, or are recognised side effects of these medicines.

The safety of these vaccines and antivirals will continue to be kept under close review. You can help us by reporting any suspected adverse reactions using Yellow Card.

Article citation: Drug Safety Update Feb 2010, vol 3 issue 7: 3b.

Published 11 December 2014