The 'no' To Mixing Vaccines From Spanish Scientists: "you Have
Health

The ‘no’ to mixing vaccines from Spanish scientists: “You have to put the second one from AstraZeneca”

“We are experiencing a ‘scientific reality’ in real time that, if we had done it with other drugs, we would not have had any,” says scientist Eduardo López-Collazo.

Above, Eduardo López-Collazo;  below, Fernando Moraga-Llop;  and to the right, Margarita del Val.

Vaccine development is a complex process that, in most cases, takes years. To give just one recent example: last year, for the first time in a decade, a prototype HIV vaccine reached phase III trials. The pandemic has made the international scientific community have today available not one or two, but several types of vaccines that they have a very high efficacy when it comes to counteracting the disease caused by the coronavirus Sars-CoV-2 and that they have fewer adverse effects than the majority of medicines that we keep at home.

Despite unquestionable scientific success, the Janssen and AstraZeneca vaccines have been called into question after “rare and serious” blood clots were found in some people. This Wednesday, the European Union announced that it will not renew the contracts with Janssen and AstraZeneca for 2022, and Denmark has said that it is definitively suspending vaccination with the Anglo-Swedish drug. To this we must add that France and Germany have been the first two countries to decide that, regardless of what the WHO, the European Medicines Agency and the scientific evidence say, they are going to put a second dose of Pfizer or Moderna to people who have received the first from AstraZeneca.

In our country, the Ministry of Health decided to limit the use of this injection to people between 60 and 69 years of age. However, there is an important population group – around two million teachers, police, firefighters and other essential personnel– who were vaccinated with AstraZeneca, should receive the second dose in the coming weeks and is currently in limbo. What will happen to them? The Minister of Health, Carolina Darias, said a week ago that the Executive was evaluating the option of putting a second dose of another vaccine, but that it was an issue that “is yet to be determined” that would be resolved “in the coming weeks”. The truth is that time passes, some countries begin to make a move and Spain still hasn’t made a decision.

What should our country do? There are more and more voices that point out that the vaccination process should continue its course, as it had been designed, since “there is no not a single clinical trial that supports the use of two or more vaccines different”. Who speaks forcefully is the scientist Eduardo López-Collazo, director of the Health Research Institute of the La Paz University Hospital in Madrid.

Collazo’s position makes sense if we balance the urgency that exists to immunize the population and the risk that these vaccines offer. “Scientists in general are a very heterogeneous human group that can have different opinions, but I have not found anyone who is against these vaccines that are being removed due to thrombi that have been detected. It is something that was within what was expected, ”says the specialist.

“Medications are not perfect”

To give just a couple of examples. A study published in The Lancet in 2017 pointed out that only in the United Kingdom are some 20,000 hemorrhages and around 3,000 deaths per year associated with the practice of taking an aspirin every day. The famous contraceptive pill is not recommended for women over 35 years of age, with obesity and smokers, precisely because of their risk of thromboembolism. And what goes further: some studies estimate that Covid-19 is a disease that can cause thrombi in 10-15% of those infected.

“Medications are not perfect and never will be, and we are being asked to be ultra-perfect. We are living a scientific reality show in real time that, if we had done it with other drugs, we would not have had any. The vaccines, both Janssen’s and AstraZeneca’s, are better than many medicines we have, and they are saving many lives”, he insists.

Fernando Moraga-Llop, vice president of the Spanish Association of Vaccinology (AEV), is of the same opinion as Collazo and points out that there are three possible scenarios for people who received the first dose of AstraZeneca: in two of them (putting a second dose of Pfizer or Moderna, or leave those vaccinated with the former) there is no scientific evidence. “Suspending the second dose is not appropriate, it is not correct because there is no scientific evidence to support it. The technical sheet states that patients should receive two doses and that the vaccine is more effective if the second is given at 12 weeks”, he points out.

Moraga-Llop acknowledges that the interchangeability of vaccines, despite being an alternative that seems to work, is also not an option given the mistrust that has been generated around Janssen and AstraZeneca. “This second scenario today also has no scientific evidence. Covid-19 vaccines are not interchangeable. If the first dose is from AstraZeneca, the second has to be too. The same happens with Pfizer”, warns the expert. Some animal studies have suggested that this alternative might offer a boosted immune response, but for now it’s just that, animal studies. The trial that is being carried out in the United Kingdom to test the interchangeability of vaccines may still take a few months to complete.

For the vice president of the AEV, put second dose of AstraZeneca is “the only” correct scenario. “That’s what the data sheet says, that’s what the EMA recommends, that’s what the WHO, the UK drug regulatory agency and many other scientific societies recommend. It is the only scenario that has evidence. Madrid and Andalusia have requested that people who received the first dose can receive the second of the same vaccine with informed consent, “he stresses.

But Moraga-Llop and López-Collazo are not the only scientists who have positioned themselves against betting on a second dose of another vaccine in Spain. A few days ago, Margarita del Val, the prestigious virologist and researcher at the Severo Ochoa Molecular Biology Center (CSIC-UAM) also took a stand in the debate and summarized the general feeling of the Spanish scientific community. “There is no zero risk [a la hora de aplicar una vacuna], but what cannot be done are experiments of something that is not proven, as it is to combine vaccines to try to avoid a minimum risk ”.

“There are probably no problems mixing two vaccines, but if we are strict, there is no clinical trial to support it. We are discrediting well-done clinical trials and yet, we are in favor of mixing vaccines, when it has never been done. Most likely, nothing will happen, but let’s be strict”, says López-Collazo. “I don’t think vaccination should be delayed because of this,” he concludes.