Vaccinations help us to strengthen our immune system and protect us from infectious diseases. This is the cheapest and most effective health intervention; it has very few adverse effects and a good risk-benefit ratio. Antoni Trilla is head of the Department of Preventive Medicine and Epidemiology at Hospital Clínic, a researcher at ISGlobal, lecturer in the University of Barcelona’s Department of Public Health and secretary of the UB Faculty of Medicine. He has advised the Government of Catalonia’s Ministry of Health, the Spanish Government’s Ministry of Health and the European Centre for Disease Prevention and Control in the area of communicable diseases.
Vaccination is the most widespread mechanism for preventing infectious diseases. What does it involve?
Vaccines do not stop us from catching diseases: what they do is stop a disease from developing if we are infected. If we come into contact with an infectious agent, vaccines prompt our bodies to activate a series of defence mechanisms that help us to react more quickly, more effectively and, if possible, avoid the disease. The best vaccines we have, such as the polio vaccine, are effective in 98 or 99% of cases, so it is practically impossible to develop the disease if you are vaccinated. Others, however, like the flu vaccine, barely give us 50% protection. So there’s wide variety in vaccines.
There are also differences in the way vaccines are produced: some are made from fragments of microorganisms or from part of the viral envelope, for example. We are gradually eliminating the need to use live viruses, but if microbes are contained in a vaccine they are attenuated. Apart from a very few exceptions, which do however exist and need to be monitored, it is biologically impossible for a vaccine to cause the disease that it protects against.
«The risk-benefit ratio of vaccines is one of the best we have»
The risk-benefit ratio of vaccines, compared with that of other medical interventions, is one of the best we have. A vaccine is generally very economical: it is administered once or twice at the start of life and may protect us forever from many childhood diseases. Therefore, with a simple intervention at a very low cost, we can avoid many illnesses over the years. Some vaccinations do need to be repeated a certain number of times, and others are more expensive. But the capacity of vaccines to prevent disease in relation to their price is extremely positive.
What adverse reactions can they cause?
All drugs have some side effects. We always have to accept a certain level of risk. Most of the undesirable effects of vaccines are well-described and monitored – we know how frequently they occur – and, above all, these effects constitute minor problems: pain at the injection site, one or two days of feeling unwell, perhaps a slight fever, etc. Of course, as with all drugs, some people may be allergic to vaccines or to some of their components. It is also true that one in every hundred thousand or one in every million people vaccinated could experience a serious side effect. But these are extremely low probabilities.
How many people get vaccinated?
In Spain, between 95% and 100% of the population are vaccinated against preventable childhood diseases. The results are clear: if we introduce a good vaccine, the disease will be almost eliminated after a certain amount of time. However, the virus will not disappear, as it will survive in places where the population is not vaccinated. We haven’t been able to totally eradicate smallpox, and so the virus and vaccines are still kept in some high-security laboratories in case it returns. As we continue to vaccinate, it will be very difficult for these diseases to reappear. But they continue to exist.
For example, a few years ago there was an outbreak of over ten thousand cases of measles in France; and now there is an outbreak in the USA. The US outbreak is small, but has generated enormous publicity because the disease was probably caught at Disneyland. This case has rekindled the debate between proponents of natural medicine who are anti-vaccination, and the medical community, which has taken a hard stance for the first time in many years. There is even talk of preventing children who are not vaccinated against flu from going to school or of sending them home during an outbreak, so that they do not infect others.
Can public health risks arise because part of the population chooses not to get vaccinated?
From an individual perspective, this is a decision that we must respect. However, the debate is complex, because it affects both individual and community health. If the number of people who get vaccinated is below levels that provide protection, diseases may reappear. And not everyone can be vaccinated. For example, a child who is receiving chemotherapy for cancer cannot be vaccinated. Neither can a patient with an immunosuppressive disease, nor a person who is allergic to some of the vaccine’s components. If there are enough people vaccinated in a group – the percentage depends on each disease, but is always high and never below 80 to 85% – then the microorganism cannot spread effectively. The transmission of the infectious agent is blocked.
Is this what is known as herd or community immunity?
Exactly. It’s called herd immunity because it reflects the way sheep behave: the largest ones stand on the outside of the flock to protect those inside that are more vulnerable. If the vast majority of the population are vaccinated, the members of the “herd” who cannot be vaccinated are still protected. However, if we add the number of people who don’t want to be vaccinated to those who cannot, the proportion of people who are vulnerable to infections may increase to the point that community immunity disappears and the disease can be transmitted again. We cannot allow this to happen, except for justified medical reasons. We can even understand religious reasons. But the false belief that vaccinations cause diseases or are harmful has no scientific basis.
Why is a segment of the population opposed to vaccinations?
The first argument put forward is that there is no need to be vaccinated against diseases that don’t exist or rarely occur. However, this is a fallacy. In fact, the opposite is true: we have managed to control these diseases through vaccination, but they have not disappeared. Therefore, it is clearly important to continue to vaccinate. Another fear is that vaccines are harmful. This isn’t true either. Products that contain a type of mercury have been used to keep certain vaccines sterile, but this mercury is rapidly eliminated from the body and is not toxic. There is another kind of mercury in foods – particularly fish – that is more toxic and accumulates in the body. If we don’t consume industrial amounts, we’ll be fine; but this kind of mercury is more dangerous than the type that is found in vaccines. Finally, another argument is that vaccines cause serious illnesses.
An article by Andrew Wakefield published in The Lancet in 1998 linked the MMR vaccine to autism in twelve children. What impact did this study have on the vaccination rate?
Confidence in the MMR vaccine plummeted: the vaccination rate dropped and measles reappeared in England. One child even died because of complications caused by measles. There is no cause-effect relation between the vaccine and autism. In fact, Wakefield was struck off the medical register as it was shown that his study was fraudulent. He’d made up some of the data and he didn’t have the authorization of his hospital’s ethics committee. In addition, there was a conflict of interest as he worked for a legal firm that wanted to sue the vaccine manufacturers.
In Spain we have a similar case: that of the human papillomavirus. Several years ago, three girls suffered from serious neurological symptoms after being given the vaccine. The Ministry of Health appointed an independent commission to determine whether there was a link between the vaccine and the girls’ symptoms. It was shown that there was no association. However, as the commission’s findings and ruling were not widely publicised, anti-vaccination groups continue to insist that what was shown wasn’t actually true and some people are still opposed to this vaccine.
The efficacy of this particular vaccine remains to be seen, as not enough time has passed to know how many cases of cervical cancer have been prevented. However, the vaccine has a solid scientific basis, and its safety is assured. Due to the work of foundations such as the GAVI Alliance (formerly, the Global Alliance for Vaccines and Immunisation) and the Bill and Melinda Gates Foundation, which have managed to substantially reduce the price of the vaccine by negotiating with the manufacturing company, this vaccine is now available to children from countries in Africa and Asia where the problem is still much greater than it is here.
To sum up, are the benefits of vaccination greater than the risks?
«The main risk of vaccines is not receiving them»
In reality, the main risk of vaccines is not receiving them. Parents who don’t vaccinate their children should understand that the only thing they’re doing is exposing their offspring to the risk of contracting measles, mumps or whatever. Nothing else.
This is a problem of belief versus science: we use scientific arguments; they use beliefs. We must stress that vaccines are efficient and have increased our life expectancy by preventing some diseases and disabilities. We have to pay a price in the form of some side effects and the investments that are involved. But the benefit in scientific terms is clear.
The health authorities recommend and provide vaccines, but they are not compulsory. Do you think we should change the legislation?
I think that we should convince rather than force. If people are not convinced, then we should introduce some restrictions. This is already the case for health professionals in many US hospitals: if they are not vaccinated, they must wear a mask during the flu season to avoid passing the virus to patients. Here we cannot force people, and I think that’s a good thing. What we must do is explain ourselves well, and activate protection mechanisms. For example, only vaccinated staff should work in very high risk environments such as intensive care or transplant units. The alternative of forcing people to receive vaccinations would definitely be counterproductive.
What criteria are used to draw up vaccination schedules?
The vaccination schedule is drawn up in accordance with scientific associations and taking into account the threats (at what age a disease tends to affect people) and the potential consequences for a child. This is the schedule for routine vaccinations; those that are recommended for everyone. However, we do not force people or legislate: we only recommend. Some people consider that we give too many vaccines in too short a period, and that a child’s body cannot tolerate this. However, vaccines have developed substantially: the antigenic load is determined precisely: it is very small and does not lead to any immune system disorders. In fact, it is 300 times more powerful than it was 50 years ago and the dose that we administer is smaller.
What are the most common non-routine vaccinations?
«Every year we give the flu vaccine to 20% of the population»
Every year we give the flu vaccine to 20% of the population, which is the percentage of people at risk and includes children, the elderly, and those with serious illnesses or more than one chronic disease. The vaccinations that are recommended by the national health system and included in the vaccination schedule are free. However, in some circumstances other vaccines are provided when a person meets a specific condition. For example, the pneumococcal vaccine is given to people under 65 who have had an accident or illness in which they have needed to have their spleen removed. There are other more complicated cases, which are the subject of current debate, such as the varicella vaccine. “Official” epidemiologists consider that if people are given this vaccine when it is not indicated, more cases of chicken pox may occur in adults. This is not a very strong argument in my opinion, at least not one which has enough scientific weight. However, the state has decided to withdraw the varicella vaccine from pharmacies, exercising its authority and legislative power. Now it is only available in hospitals if the patient meets specific conditions. We need to accept that decision but at the same time we will also need to calmly review the matter with arguments that are both scientific and pragmatic. It’s not that far removed from the debate about the pressures that are brought to bear by the pharmaceutical industry, which are sometimes subtle but can also be felt quite clearly.
In recent years, there have been some health alerts over certain communicable diseases such as the influenza A virus. What role has the pharmaceutical industry played in these crisis situations?
Is the final aim of the companies to sell drugs? Obviously. But compared to the rest of the pharmaceutical market, the vaccination business is very small: I would say that it accounts for about 8 to 10% of the total. You get a vaccination when you’re one year old, for example, and then another when you’re 24. This cannot compare with the revenue generated by chronic treatments. HIV positive patients, for example, have to take a number of pills a day for a period of 40 or 50 years. What’s more, vaccinations tend to be cheap.
«We must also realise that, objectively, the pharmaceutical industry contributes more to improving our health than worsening it»
Ideally, relations between the pharmaceutical industry, professionals and patients should be totally transparent: we should know who is paid, how much they receive, and for what functions. But we must also realise that, objectively, the pharmaceutical industry contributes more to improving our health than worsening it. Clearly, companies make large profits, and on many occasions we would like them to be more sensitive. It is also true that there have been cases of bad practice, which fortunately have been investigated and sanctioned. For example, some vaccines or other drugs have been promoted via unsuitable channels, and some studies have not been published because their data do not support a product. However, our society has sufficient legal and scientific controls to stop bad practice in the pharmaceutical industry; we must keep these in place and strengthen them.
Is enough being invested in research, particularly in the field of neglected or forgotten diseases?
The classic answer would be no, more should be invested. Existing funds already run into the millions; but compared to those available for other research areas they are negligible. This is also a problem of markets. And this is where states or international organizations must come in. The real objective of the industry is to generate profits. And companies will never invest in a vaccine that is not profitable. Perhaps a company wants to obtain a profit of 10. But if the price of the vaccine is cut and the company is happy to make a profit of 2, the state could fund part of the research and the company would not lose out. It would not be investing 10 to earn 20, but it could accept an investment of only 5 for a profit of 2. The result is that 20 million vaccines would be produced at €2 instead of a million at €100 that, at this price, couldn’t be sold anywhere. And why make companies invest if they don’t want to? Because this is a public health problem.
We should also remember that a lot of research is carried out in universities, with public funds. The problem is that there comes a time when private investment is needed to develop or patent product. However, all of the first stage may have been paid for with public money, so it would be right and logical for us to demand a cut in the price of a vaccine in return for the previous public investment. We would like to say that a disease has been eradicated due to the contribution of UB scientists, who not only came up with the vaccine, but also made an agreement to keep the price down with the company marketing the drug. Obviously, there are more complex situations, but this is the spirit that should be encouraged: Public- and private-sector collaboration in benefit of the community at large, especially those who suffer from the illness or who do not have the means to address it without help.