“Impossible vaccines”: science against pathogens

There are many challenges in developing “impossible vaccines,” so called because of their scientific and financial complexity. Some diseases, such as dengue fever and swine fever, stand out as those for which there is still no effective treatment available today.

“Impossible vaccines” are those that face obstacles in their development. EFE/ Sergio G. Cañizares

Organized by the National Association of Health Informants (ANIS) in collaboration with biopharmaceutical company Zendal, the roundtable discussed challenges and advances in vaccine development as part of World Immunization Week. Vaccines under development were discussed, as were vaccines that currently face scientific and financial barriers.

Vaccinology became the central theme of the colloquium. It was attended by Yolanda Revilla, a virologist from the Center for Molecular Biology of Severo Ochoa-CSIC; Professor of Microbiology Carlos Martin Montañez; ISGlobal Development Director Rafael Villasanjuan; and SEIMC microbiologist Maria del Mar Thomas. The debate was moderated by Beatriz Diaz, Zendal Communications Director and co-delegate of ANIS in Galicia.

As Diaz explained, only 5% of the vaccines being developed reach the market. Developing a single vaccine could cost a staggering €1 billion. The roundtable discussed this issue as an obstacle limiting vaccine development. This especially happens with diseases such as dengue fever, malaria, swine fever, HIV and tuberculosis.

Tuberculosis: 100 years without a new vaccine

For example, in the case of tuberculosis, a disease as old as humanity, we have gone 100 years without a new vaccine, despite the fact that it is one of the leading causes of death worldwide (1,300,000 people every year) since it exists vaccine, but it is not effective against pulmonary tuberculosis, which is the most common form of the disease.

Moreover, according to Carlos Martín Montañez, the main obstacle facing this much-coveted vaccine is that “we are already accustomed to these numbers. I think that if this were a new disease, society would certainly react by demanding a response. “Different,” he said, also emphasizing that these are “extremely expensive” processes and that the most advanced trials at the moment are the MTBVAC vaccine trials being conducted by IAVI and Biofabri (a subsidiary of the Zendal Group) as an alternative to the MTBVAC vaccine. BCG vaccine for newborns and for the prevention of tuberculosis in adolescents and adults.

Swine fever: genetic variability

Virologist Yolanda Revilla, for her part, expressed her opinion based on her experience, having devoted more than 30 years to the study of swine fever. At the round table, he noted that the difficulty of developing a vaccine against the disease lies in the enormous genetic variability of the virus, since it has more than 170 possible antigens. In addition, he recalled that many years ago swine fever was endemic in Spain and that here “we were only able to eradicate it through animal sacrifices, which led to “huge environmental and economic losses.”

“What happens with this virus is that it gives you the opportunity to learn for life; “He is a master, he knows a lot, he has a lot of proteins, and each of them constantly uses them to do something against an effective response,” he added.

Despite this, the virologist is optimistic about the possibility that this vaccine will no longer be one of the “impossible vaccines” and that a cure for this disease will soon be created.

Dengue, malaria and phages

The dengue virus, which affects 400 million people every year and kills around 40,000, poses a variety of problems. Due to the geographical expansion and presence of the tiger mosquito in regions such as the Mediterranean, developing a vaccine against this disease is challenging.

Rafael Villasanjuan stressed that while there are several vaccines in development, research led by Takeda may offer the most promising solution. In the case of malaria, the difficulty is the high cost and logistics of administering multiple doses outside of standard vaccination programs.

On the other hand, microbiologist Maria del Mar Tomás, who has researched bacterial resistance and the prospects of using phages as an alternative treatment, highlighted the great progress that Europe has officially accepted phages as medicines.

“It has been observed that there is synergism with antibiotics and sensitization of bacteria in the presence of phages, which, in addition to being used as a treatment, are of the lysogenic type that resides within the bacteria, and this means that they have many biotechnological applications as well as for vaccine development. Its function is to enter and exit bacteria carrying genes without lysing the bacteria. They are the main transport vectors for antigenic vaccine proteins, and so this is a very, very interesting area, “because also, our body is “composed of more phages than bacteria, so it won’t act against them,” he added. .

In addition to the above, the microbiologist warned of an approximately 50% increase in cases of gonococcal sexually transmitted infections following the pandemic, which she interpreted as “young people have lost their fear of sexually transmitted diseases, and a vaccine will have great potential because it this is already cultural, there are people who have up to three cases of gonococcus infection in a year.

What have we learned from the pandemic?

As panelists noted, the COVID-19 pandemic has provided valuable lessons in diagnostics, surveillance and logistics. However, he also emphasized the need to address issues related to the concept One health. For example, the lack of a global vision for climate change and the need to diversify vaccine production.

Despite the obvious difficulty and high cost of developing these “impossible vaccines,” experts pointed to promising advances on several fronts that could have a significant impact on global health.