The most likely cause was some sort of contamination. One guess floating around at the time was that the vaccines were intentionally poisoned by Syria's Bashad al-Assad as a way to subvert the rebellion. Given the situation in that country, it was not that crazy of an idea. Some suggested bacterial infection with Staphylococcus aureus. Only lab tests would confirm the presence of the bacteria. Another guess was that the vaccines were expired. If that were the case, however, the vaccine would simply have been less effective, not more likely to cause an adverse reaction. And then there were preliminary reports that there was a mixup, with the muscle relaxant Atracurium being used instead of the sterile diluent.
Now we have an interim report from the World Health Organization.
The statement from the WHO clarifies several points. First, the death toll was 15, not 30-50 as initially reported in a number of media outlets. Second, there is no evidence that the vaccine nor its correct diluent caused any injuries. Third, the apparent culprit was, indeed, Atracurium, which had inadvertently been added to the vaccination packs instead of the diluent. Here is the full WHO statement:
The anti-vaccine community, eager to seize upon any hint of vaccine injury, simply concluded that the vaccine itself was to blame, rather than taking a more nuanced and cautious approach to the incident. In their zeal to villify the MMR, they rushed to judgment. Indeed, one anti-vaccine activist, Anne Dachel, opined, "So will this be due to cyanide, with absolutely nothing to do with the vaccine itself? PR will be working 24/7 to exonerate the MMR." Dachel preemptively dismissed any conclusion that did not blame the measles vaccine. Now that it has been shown that the vaccine itself actually was not to blame, don't hold your breath waiting for Ms. Dachel to write anything clearing the vaccine.
A WHO assessment of the cause of the death of 15 children in rural Idleb, northern Syria has concluded that the most likely cause of the event was the incorrect use of a drug called Atracurium as a diluent for Measles/Rubella vaccine.
There is no evidence that the Measles/Rubella vaccine itself or its correct diluent were the cause of this tragic event.
Measles vaccine has to be reconstituted with a diluent prior to use. All evidence available to the assessment team indicates that the incorrect use of Atracurium as a diluent was the cause of the deaths. Atracurium is a muscle relaxant and is used mainly as part of the anaesthetic procedure for surgery. The Atracurium ampoules were incorrectly added to vaccination packs prepared in one District Vaccine Distribution Centre in Idleb Governorate and distributed to four vaccination teams on the second day of the measles campaign.
Vaccination is one of the most basic and critical health needs in emergencies to protect populations from the risk of contracting deadly but preventable disease. The risk of measles and polio in Syria remains extremely high; as such, WHO urges all health partners to rebuild confidence in vaccination and ensure that all children have access to life saving vaccines.
The WHO assessment was carried out by a team composed of experts in the investigation and management of adverse events following immunization from the Organization’s headquarters and regional offices.
Then there were tweets like this:
I have not seen one member of that community come out and say, "No, we were wrong. It wasn't the vaccine." Ideology trumps all, it seems. Despite the claims that this was vaccine injury, this wasn't a case of vaccine injury.
Unfortunately, the fact that it was human error, rather than the vaccine, is little comfort, especially to those families whose children died because Atracurium was used instead of the vaccine's diluent. While I can understand how it happened, this never should have occurred. The vials for the muscle relaxant and the vaccine diluent are reportedly very similar, but that is no excuse. Those packing the vaccine packs ought to have had double-checks in place to ensure they were put together properly. In fact, the Atracurium never should have been anywhere near where the vaccines were stored. If separate storage was not available, then extra safety checks would have been all the more important.
It is going to take a long, long time for trust to be reestablished after this tragic event. And in the meantime, children will contract measles. Most will recover. Many will suffer through a severe course of illness. And some will die from the disease.