Immunization standards

Safety of Quinvaxem (DTwP-HepB-Hib) pentavalent vaccine.

10 May 2013

On 4 May 2013, the Ministry of Health of Viet Nam announced the temporary suspension of Quinvaxem, a combination vaccine that protects against diphtheria, tetanus, pertussis, hepatitis B and Haemophilus influenzae type b infections. This suspension follows a recent increase in the number of reports of adverse events following immunization (AEFI) with Quinvaxem and, in most instances, oral poliovirus vaccine, including the death of young infants within a few days of receiving the vaccine.

WHO was invited by the Viet Nam authorities to review the 43 serious AEFI cases that have been documented in the country since Quinvaxem was introduced in mid-2010, including the 21 most recent cases (12 deaths and 9 who recovered) reported between 1 October 2012 and 31 March 2013. This review involved one independent clinical expert together with WHO staff from Headquarters, Regional and Country Offices who collaborated with national experts and UNICEF colleagues in assessing clinical and other information available.

Based on this review of the reports, it appears that 9 non-fatal cases could correspond to known but rare vaccine reactions. Such transient reactions, including allergies, seizures and decreased muscle tone, are expected in a very small number of recipients of the vaccine and are declared in the product insert accompanying the vaccine. These relatively minor effects of the vaccines pass, while the benefits of the vaccine remain, and save lives.

After careful investigation, it was found that the other serious AEFIs, including those which resulted in fatalities, reported in Viet Nam were either coincidental health problems related in time but not related to the use of Quinvaxem, or cases for which the information available does not allow for a definite conclusion (which is a common situation when individual cases are assessed). However, for those serious and fatal cases there are no elements that could be consistent with the use of the vaccine.

Quinvaxem was prequalified by WHO in 2006 and, to date, has been used in more than 90 countries with more than 400 million doses of vaccine administered. This and other similar pentavalent vaccines are extremely safe: no fatal AEFI has ever been associated with this vaccine. Quinvaxem can cause limited reactions such as fever or local reaction (transient inflammation at the injection site) in a small proportion of vaccinated infants.

WHO is collaborating with the Viet Nam authorities in further assessing those events. AEFIs associated with Quinvaxem from other countries are also consistent with the known reactions that could be expected from each of the individual vaccine components. An update will be provided in due course to relate progress with the assessment of AEFIs from Viet Nam. Considering the above information, plus the outcomes of a review of information on the quality of the vaccine by WHO, and the advice from the National Regulatory Authority (NRA) of record for prequalification purposes, Quinvaxem remains on the list of prequalified vaccines. WHO continues to advise UN agencies that Quinvaxem is suitable for supply.

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