One of the reasons that many people (parents and professionals) are reluctant regarding the Bexsero vaccine It is its effectiveness. When the vaccine came out, there were useful data in the laboratory, but not what would happen after it was administered, so it could be said that it takes a while to vaccinate children without knowing for sure if it is very effective or not It is so much.
Already a few months ago, when I spoke extensively about the vaccine, I made an advance on the first conclusions thanks to the data that came from universal vaccination in the United Kingdom. Now the same data published in a study have emerged and it is suggested that, in Spain, More than 380 thousand people should be vaccinated to avoid a case of meningitis B. However, the calculation has an important nuance, which we will see next.
In the United Kingdom the effect of the vaccine is already noticeable
The study, published in Lancet and translated into Spanish in Evidence in Pediatrics, analyzed the effectiveness of the vaccine for the first year of life (that is, when children take one or two doses, but are not yet fully vaccinated). Taking into account that precisely in the first year is when the incidence of meningitis B is greater, we can consider that it is a very valuable fact.
They saw that for babies who had received two doses of Bexsero The effectiveness of the vaccine was 82.9% for all strains of meningococcus B, Y 94.2% for the strains included in the vaccine. In fact, in the ten months that the study lasted, it was observed that cases of meningitis B in the population were reduced by 42% with respect to the expected: if in the previous years they had had an average of 74 cases in children under 12 months, at the time when children were being vaccinated there were 37 cases.
These figures, of course, should improve every year, if we consider that there will be more and more vaccinated children, not only under one year, but also over one year: those who were vaccinated a year ago and now have two years (which because they are vaccinated they have less risk of catching the disease and transmitting it).
But the incidence of the disease is VERY low
The data are from the United Kingdom, so to extrapolate them to our population, from Spain, we assess the frequency of cases we have here. In the same publication the estimate is made, and since there are 0.31 cases per 100,000 inhabitants (2014 data that you can read here), it is considered that To avoid a case of meningitis B, 388,652 people should be vaccinated.
Avoiding a case is not avoiding a death, it is avoiding a contagion, so to avoid a death, considering that the mortality of meningitis B is approximately one in ten cases, almost four million people should be vaccinated.
Explained in this way, it seems absurd that we are spending 106'15 euros per vaccine.
However, babies under one year are at greater risk
However, the incidence of 0.31 cases per 100,000 inhabitants is a statistical figure that speaks of the general population. And meningitis B does not affect the entire population in the same way. If we all got sick in the same percentage, the vaccine would make no sense, but the children get sicker, much more.
According to the same data of 2014:
For serogroup B, the highest rates corresponded to those under 5 years old (9.98 cases per 100,000 inhabitants for those under 1 year old and 1.24 cases per 100,000 inhabitants in the group from 1 to 4).
The difference is clear and evident: meningitis B is very rare always, but the incidence is much higher in those under 1 year (0.31 per 100,000 is not the same as 9.98 per 100,000). So if we calculate how many babies have to get vaccinated from Bexsero to avoid a case of meningitis B the result is just over 12,000. There are still many, but they are no more than 388 thousand.
And to avoid a death from meningitis B? Well ten times more: you have to vaccinate more than 120,000 children. If in Spain about 400 thousand children are born a year, it could be said that if all were vaccinated 3.3 deaths from meningitis B would be avoided Y about 33 cases of illness.
Does this new study change anything? Not for me. The message remains the same: it is a very difficult disease to catch, it is almost It is impossible for our baby to take it, but it is not impossible. 9'98 babies out of every 100,000 are very few babies, but if your baby is one of them ... well, better not think about it. It is a serious disease.
I do not want to scare or remove fear with these data, just explain them as they are, so that parents value them with perspective.
But, there could be a conflict of interest!
We read in the study, in the section of possible conflicts of interest that:
Two of the authors have research contracts with the pharmaceutical industry (including GSK), but report not receiving personal compensation.
This means that these two authors may not be impartial when handling the data and that in reality the efficiency is not as high as the data says, so that everything I just explained may be true or it may not be. As we also have no data from any independent study, I can only explain it and say this too.
In addition, you may have heard or read that vaccine protection does not seem to go beyond five years. There is a study published in 2015 that corroborates this, that after five years of vaccination children are left without sufficient protection and again they are susceptible to contagion. This means that it is possible that within a time it is said, to parents who have vaccinated their children, that within four or five years of having done so they need a new dose of remembrance.
Although looking at it well, the need to administer that dose of recall will be relatively low. The incidence of the disease after five years is much lower, so that if the vaccine has protected a baby for the first five years, from that moment on, any decision in this regard (whether or not to put it) should be considered more or less correct.
