This year, ANMAT approved two long-awaited vaccines: dengue and shingles. And in May, the U.S. FDA gave the go-ahead to two vaccines that target the same virus: respiratory syncytial virus, which causes bronchiolitis. After the Covid spurt, on the vaccinology board the chips seem to move faster. Are we entering a new era of vaccines?
"Vaccines are one of the most powerful public health tools in the world. They prevent 4 to 5 million deaths each year. With them, smallpox has been eradicated, polio has practically disappeared and cervical cancer has the potential to become widely preventable," says Susana Baldini, medical director of the Argentine Chamber of Medicinal Specialties (CAEME).
In this sense, the approval of the dengue vaccine of the Japanese Takeda in the decline of the worst epidemic was good news to face the next season. Although the vaccine showed better performance in some of the four serotypes, it has an overall efficacy of 61% and 84% for hospitalization, and can be received by anyone over 4 years of age, whether or not they have had dengue. There's no release date or price yet, but it's expected to arrive in the spring.
The one that is already available in the private sector is the herpes zoster vaccine from the British laboratory GSK, which costs $ 32,000 per dose. There are two and apply to people over 50 years of age or over 18 years of risk group with an interval of between 2 and 6 months to prevent this disease, commonly called shingles.
Vaccines cause 4 to 5 million deaths each year. AP Photo/File
"It causes disabling pain for a long time. Postherpetic neuralgia can last for a year and affects between 5% and 20% of patients. And 5% have ophthalmic herpes, which can cause vision loss, "says Beatriz Seoane, medical director of GSK Argentina, who warns about the need for rapid consultation in the face of symptoms. The virus develops in those who have ever been infected with chickenpox: it is estimated that one in three people over 50 will have zoster.
The bronchiolitis vaccine, the one that is coming
Last week, the FDA approved Pfizer's respiratory syncytial virus (RSV) vaccine, which had the largest number of participants in its clinical trial in Argentina. Also in May, it had authorized GSK's vaccine, both for those over 60. It is a milestone for immunology because an RSV vaccine has been studied without success for six decades.
Gonzalo Pérez Marc is a principal investigator at the Central Military Hospital, one of the centers where Pfizer's was tested. He assures that the learning that was made to get a Covid vaccine in record time is already having a spillover effect.
"Clinical studies that used to take six to ten years now take a year and a half or two. It is not that before it was investigated more or better, but that there were many bureaucratic and regulatory processes very dissimilar, "he says. There was multidisciplinary work, political will and funding. And that also resulted in technological innovation.
The key to the RSV vaccine is the pre-fusion protein, one of those used by the virus to bind to the cell, which made it possible to obtain more and better neutralizing antibodies.
But the pandemic brought a revolutionary change: for the first time, messenger RNA (mRNA) was used, the platform that allowed vaccines to be adapted to variants in record time.
mRNA is Moderna's adult respiratory syncytial vaccine, also tested in Argentina. Its regional medical director, Rolando Pajón, is confident that the FDA will approve it this year and says they will not wait for that authorization to submit the request here.
"RSV causes disease at both ends of life, but the percentage of hospitalization and death is higher in the elderly," he says. Graciela Morales, director of Vaccines for Emerging Markets at Pfizer, agrees: "In countries with good epidemiological surveillance, such as the US, there are between 60,000 and 160,000 hospitalizations per year and between 6,000 and 10,000 deaths."
Both laboratories will move forward with clinical studies of their vaccines in the pediatric population. In fact, Pfizer has already tested one in pregnant women to see the transmission of antibodies to the baby and the FDA's vaccine advisory committee recommended its approval. "If it happens, it would be the first vaccine available for children from birth," says Morales, who says Argentina is "on our list of priority countries to submit to the request for authorization."
The FDA has also just approved a one-dose passive immunization drug for healthy babies (which must be given every year) from Sanofi and AstraZeneca: from the French laboratory they confirmed that they submitted the authorization process to ANMAT.
Pérez Marc does not contain the enthusiasm for all these advances against the RSV. "The vaccine for pregnant women has to be added to the vaccination schedule. That, enhanced with these monoclonal antibodies in high-risk patients would be a spectacular strategy and will change pediatrics, "he says. And share the link of www.equipociencia.com for those who want to join as volunteers to the clinical trials still underway (such as the Argentine Covid vaccine) and all those that are coming. Because this is just the beginning.
Messenger RNA and the panvaccine
"Messenger RNA is a revolution," Pajón says. In this type of vaccine, a fragment of a protein is introduced from the outer membrane of the virus, the cells produce the viral protein and the immune system recognizes it and generates the antibodies.
Moderna is testing an influenza vaccine with this platform and will soon test the Covid + RSV combination with the goal of reaching a panvaccine that protects against all three viruses. "We are much closer," he says.
"There are vaccines that are not going to be replaced because they are tremendously effective, such as meningococcal and pneumococcal conjugates. But before 2030, messenger RNA will be the dominant platform." From Sanofi, its director of Vaccines for the Southern Cone, Florencia Esquivel, says that they want to have "10 new vaccines under study by 2025, including 6 with RNA technology." CAEME shares another fact: today 860 trials of new developments or forms of administration are underway, in different phases.
"RNA is being studied in HPV, cytomegalovirus, herpes zoster, malaria. And next year comes the new generation of Covid vaccines that amplifies the cellular response, "adds Pérez Marc.
The future: HIV and missing vaccines
Daniela Hozbor is a researcher at Conicet and an expert in vaccinology. She agrees on the catalyst that was the pandemic and brings her view on where we are and where to move forward. "We have changed the development paradigm, which was previously to isolate the pathogen, inactivate or attenuate it and then immunize. Now there is much more technology and knowledge and more chance of success, but it is still a complex task, "he warns.
A child receives the polio vaccine. Photo AFP / File
Specifically about the dengue vaccine, he points out that it is "an important step", but that prevention measures must be maintained. And asked about what diseases await her vaccine, she says that we have pending malaria, leishmaniasis, bacterial infections such as Staphylococcus aureus or Streptococcus agalactiae and, of course, HIV.
"The important thing is to maintain the value of vaccines and vaccination all the time," he says about the need to achieve good coverage because "there are no good designs if vaccines are not used."
Regarding HIV, Pérez Marc explains why the vaccine has not been found so far. The virus has many mechanisms by which it escapes the immune control system and one is mutates its antigens a lot. When antibodies generated by a vaccine come into contact with the virus, they do not recognize it. "But new technologies allowed us to begin to better understand other binding sites of the virus," he hopes.
Pajón recognizes that "HIV is the black hole of vaccinology." Can RNA change it? "We don't know how, but it doesn't mean we don't try. Let's say you want a navy blue car. The other technologies give you different shades, but RNA gives you the one you have in mind. This biological fidelity and learning in clinical studies will bring us closer to a candidate with more realistic chances of success."
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