Modern vaccines are safer than those used decades ago and the Europe’s approval process for new vaccines is “rigorous”, according to Dr Pieter Neels, Vice Chair of the Vaccines Working Party of the European Medicines Agency (EMA) and member of the Committee for Medical Products for Human Use (CHMP).
Click here for a summary of this interview
How do vaccines compare with medicines in terms of their safety profile?
I don’t think vaccines are that different to pharmaceuticals in terms of safety profile but, of course, vaccines are given to healthy people to prevent illness so of course we are very sensitive to whatever safety issue there might be.
At the EMA, all products go through a rigorous process which most often involves a request for additional information to help allay any concerns people may have in mind.
The difference is that vaccines are given to healthy people and they have logically a low tolerance to adverse events. When smallpox was common, the risk-benefit of smallpox vaccine was still seen positive because benefits were so large, despite the rate of devastating serious side effects.
Has safety improved over time?
Yes, certainly. If you look at smallpox, the vaccines we have today are much safer. The other story that is very well known is the shift from whole cell pertussis vaccine which involved injecting 3,000 antigens, towards acellular vaccines which involve about three different antigens to be injected. Consequently the risk of fever is much lower.
Over last decades, things have changed a great deal. Today, between 50 and 60 antigens are given to infants in the first 6 months of life as opposed to thousands they would have received in the past.
Why has perception of safety deteriorated?
We don’t see many of these vaccine-preventable diseases anymore. Most people in Europe have not seen somebody dying from tetanus or measles. People believe measles is a very mild disease – which is true in most cases – but it can kill. We can eradicate measles completely. There is no animal carrying the disease so if we vaccinate everyone with two doses we could eradicate it worldwide. It’s such a pity that people don’t understand that we could achieve by doing this.
What is your view of groups that question the need for vaccination?
There are some groups calling themselves ‘anti-vaccine’ who misrepresent the risk or take figures out of context. They have raised concerns about aluminium in vaccines but we are talking here about micrograms. On occasion, anti-vaccine groups have presented the concentration of aluminium in terms of litres but vaccines are delivered in much smaller volumes (e.g. Gardasil is delivered as 0.0005 Litre dose) so this is really taking the figures out of content. There are tiny amounts of aluminium in vaccines. Of course it can be toxic in large doses but you can kill somebody with too much water, salt or sugar as well.
There is a lot of misunderstanding. If you look at the flu pandemic it was difficult to convince people to get vaccinated. One of the most at-risk groups was pregnant women and of course there is sensitivity there because nobody wants to harm the future baby. Let’s look at the adjuvant some people were concerned about: what can be the devastating effect of the presence of 10 milligram omega-3 lipids – this substance is found in the body in much higher concentrations and some people even take it as a supplement to be healthier.
Can you describe the process a vaccine has to go through before approval?
Most vaccines are approved at European level. Pharmaceutical companies often find it easier to work with the EMA than to go through national authorities in 27 member states. The procedures are the same as for other medical products. Assessment takes about 210 days.
What about the seasonal flu vaccine? It is reformulated twice a year – can it be tested every time?
In Europe we have a special procedure, for the flu vaccines as these require to be adapted each season to hit a moving target, namely the seasonal change. The vaccine has to be tested of course, as always, for its quality. But we ask for limited clinical trials to demonstrate efficacy. The groups in these trials are small and there is criticism that the results are not relevant because of the size of the studies. The US authorities don’t ask for these kinds of trials, they just ask for quality testing.
The manufacturing process does not change from year to year and the difference in the product from one year to the next is not great. The antibody you are eliciting in the body will be a little different. If the virus has shifted a little bit after WHO has defined the next season’s virus, the efficacy might be not as good as expected but you don’t know until you look back on the flu season.
In 2009 people were vaccinated with two vaccines: the seasonal vaccine and the H1N1 pandemic vaccine. It came out that the seasonal flu vaccine was almost useless because the flu virus in circulation was almost only H1N1.
In terms of how the pandemic was handled, I would say our work can be quite frustrating. We have had a lot of criticism from people saying that we’ve exaggerated the threat from H1N1 but that’s very easy to say now. We are not able to predict the severity of a flu epidemic and to make it even more complex: the severity can increase during the epidemic; therefore we have to prepare ourselves for the worst case scenario. In the end one has to recognize that vaccines we made available were largely efficacious whereas the natural disease as a pandemic was not.
Dr Pieter Neels, Vice Chair of the Vaccine Group of the European Medicines Agency’s Committee for Medical Products for Human Use, was speaking to Gary Finnegan