Vaccines, Science and Public Health in the Age of Medical Misinformation

Interview with Dr. José María Bayas by Houda Bakkali

Dr. José María Bayas is one of the leading voices in preventive medicine and epidemiology. A distinguished figure in the study of vaccines and also in the communication of medical knowledge. In this conversation, I share his vision and expertise on the value of communication and education regarding vaccines, as well as on the challenges, benefits, and risks of these pharmaceutical products and their impact on public health and quality of life.

Dr. Bayas served as Head of Service and Senior Consultant of the Department of Preventive Medicine and Epidemiology and Director of the Adult Vaccination Center at Hospital Clínic de Barcelona, as well as Associate Professor of Public Health at the University of Barcelona and Coordinator of the Teaching Unit of Preventive Medicine and Public Health at Hospital Clínic de Barcelona. His research and publications have focused primarily on areas of vaccinology related to hepatitis A, hepatitis B, influenza, avian and pandemic influenza, human papillomavirus, herpes zoster, new administration routes, and new adjuvants. He has contributed to more than 50 books, guidelines, and monographs, authored more than one hundred scientific articles on various aspects of Preventive Medicine and Public Health, and participated in more than 200 courses and seminars, as well as numerous conferences in his field of expertise.

José María Bayas belongs to several scientific societies and is a founding member of the Spanish Association of Vaccinology (AEV), of which he served as president for eight years. He has participated in various national and international expert committees in the field of vaccinology, including the Brighton Collaboration Anaphylaxis Working Group. He also served as evaluator for the National Agency for Evaluation and Foresight (ANEP) and was part of the Medical Department of GSK Vaccines Spain as Vaccines Academy Head.

Please explain exactly what vaccines are and how they impact our body.

Vaccines are an antigenic preparation which, once introduced into the body, induces the appearance of an acquired active immunity of both humoral and cellular type — as is the case with most vaccines — with long-lasting protection. There must be only a minimal and acceptable risk of local or general adverse reactions, and this is required of all vaccines. It is non-negotiable.

A perhaps more modern definition — if I may use this expression — replaces antigenic preparation with biological preparation, because some recently developed vaccines contain genetic material — which does not mean they are infectious in any way, of course. It would be something like an instruction manual allowing the body’s own cells to produce these proteins, which will then play the role of antigens with the previously mentioned results.

What distinguishes vaccines from other pharmaceutical products?

Vaccines are pharmaceutical products, but highly singular ones, differing in many ways from other medicines such as antibiotics or drugs used to treat high blood pressure, for example, because vaccines do not act directly on the human body but rather through the immune system for the aforementioned purpose.

Do they pose risks to health?

Any human activity carries some degree of risk. Zero risk practically does not exist. Only medicines with effective curative or preventive activity — meaning those capable of curing or preventing — have side effects accompanying these primary effects, which are the reason for their use.

Do vaccines provide total protection against a disease? To what extent do they protect, and what determines this degree of protection?

It depends on the vaccine. If we are talking about vaccines designed to prevent diseases caused by a single type of microorganism, such as tetanus, measles, or hepatitis A or B, protection is practically 100% if vaccination has been carried out correctly. However, some microorganisms exist in many forms, such as pneumococcus, meningococcus, or influenza viruses — which undergo constant mutation — and in these cases, efficacy will naturally be more limited.

For routine vaccines, those included in vaccination schedules recommended for most of the world’s population, this protection is above 90–95%.

What is herd immunity?

One particularly important aspect of vaccines, and something absolutely unique to them compared to any other pharmaceutical product, is herd immunity, or collective immunity. Vaccines not only protect the vaccinated individual — if certain coverage levels are achieved, depending on the disease involved — but also protect people who, for any reason, were not vaccinated. The explanation is that microorganisms have greater difficulty spreading from one person to another. Therefore, herd immunity or collective immunity is an additional benefit provided by vaccines. The tetanus vaccine, a disease not transmitted from person to person, would be an exception, as it does not confer herd immunity.

What determines the success of a vaccine?

The immune response capacity of the vaccinated individual is limited by the competence of their immune system. People with neoplastic diseases or receiving treatments that suppress the immune system will naturally achieve more limited responses to vaccines against influenza, COVID-19, or other diseases because of this compromised immune condition prior to vaccination.

A few years ago, you told me that “there are no safer medicines than vaccines.” How are scientific advances reinforcing this statement today?

Clinical trials required for the development of a vaccine involve tens of thousands of participants — seventy thousand, eighty thousand… This is common with vaccines, but such large numbers are not typically used for the development of other pharmaceutical products. Many medicines are approved after trials involving only a few thousand or even a few hundred participants. The safety threshold required for a medicine used to treat a severe disease such as cancer is obviously very different from the safety threshold demanded of a vaccine, for reasons that I believe are easy to understand.

This high safety requirement is demanded by regulatory agencies authorizing vaccine commercialization, such as the European Medicines Agency (EMA) in Europe and similar organizations in other regions. It is also demanded by the scientific community itself, by health authorities that will authorize or reject the use of the vaccine, and, naturally, by the population, which would not accept medicines lacking such a high level of safety.

It is also important to remember that many vaccines are administered to the entire global population, as is the case with routine vaccines. Most of these vaccines are administered, of course, to children and healthy individuals, although many vaccines developed in recent years are also recommended for people who are not healthy, who have underlying diseases and are therefore at greater risk of suffering the disease or its complications.

What degree of safety is required for a vaccine to be approved?

There is no magic formula. The degree of safety could be said to be overwhelmingly superior to the harm caused by the disease.

How have vaccines contributed to individual and collective health over the last 50 years?

The Expanded Program on Immunization (EPI) of the World Health Organization (WHO) began in 1974. The objective of this program was to ensure that vaccines truly reached the entire world population because, at that time, for example, with basic vaccines such as DTP (Diphtheria, Tetanus, Pertussis), global coverage was around 5% — referring to the entire world. This, evidently, prompted international organizations to launch this Expanded Program on Immunization in 1974. Since then, it is estimated that, thanks to the EPI, 154 million deaths have been prevented, the majority of them — around 146 million — among children under the age of five. Of these 146 million, 94 million would have been deaths caused by measles. Child mortality has decreased by 40% over these 50 years thanks to vaccines. The infant mortality rate (IMR) is defined as the number of deaths of children under one year of age per 1,000 live births in one year. The global IMR in 1974 was 92.2 per thousand, and by 2024 it had been reduced to between 25 and 37 per thousand. These are WHO-UNICEF data.

The IMR in Sub-Saharan Africa has also been reduced dramatically, although it remains high, at around 45 per thousand. And, to provide some perspective, in the European Union it is 3.3, and in Spain 2.63. Therefore, these are significant differences.

Life expectancy, which in 1964 was 58.8 years, has increased considerably, reaching 73.3 years in 2024.

What do vaccination protocols consist of, and why are they important?

Vaccination protocols are a set of guidelines and regulations governing the use of vaccines in order to achieve their most efficient use among different population groups. These may include children, adults, or different population subgroups.

Who develops these vaccination protocols?

Organizations at many different levels. International organizations such as the WHO and UNICEF, regional organizations, and, of course, the health authorities of different countries, which recommend vaccination for children, adults, or people in risk situations. Naturally, scientific societies such as the Spanish Association of Pediatrics or the Spanish Association of Vaccinology, vaccination centers in both primary and specialized healthcare, among others.

These protocols define the types of vaccines, the target population for vaccination, and the specific methodology for administration and monitoring of results. These protocols are established according to age, occupational activity, underlying disease, travel, and other factors.

What do we mean by vaccine fatigue?

Vaccine fatigue has been defined as disinterest, exhaustion, or rejection of vaccination among the population. It is not an active rejection, but rather a passive one, somewhat driven by fatigue — if I may use the expression — when repeated vaccinations continue to be recommended. Obviously, when this occurs, it affects the general population but also, for example, healthcare personnel, which leads to a reduction in vaccination coverage with the consequences everyone can imagine.

It is also extremely important to combat, as far as possible, the misinformation promoted by anti-vaccine groups. Furthermore, there is great interest in developing better vaccines — better in the sense that they are easier to preserve, easier to transport, or easier to produce. Ultimately, the objective is to overcome structural barriers, social barriers, and scientific barriers.

Homeopathy is presented as an alternative to vaccines. What does its practice imply?

Some so-called alternative medicines, such as homeopathy, do not have side effects because they do not have primary effects either. In other words, they cure nothing. Another matter entirely is the potentially serious situation that may arise from the use of homeopathy if conventional medical treatment is abandoned or disregarded.

Therefore, whenever considering the use of vaccines or any other pharmaceutical product, we must always keep the benefit-risk balance clearly in mind — a balance that, in the case of vaccines, overwhelmingly favors the benefits.

Controversies surrounding vaccines are not new. Where do we stand today?

In the world of vaccines, extraordinary, deeply concerning, and even alarming events are taking place. I am referring to the fact that, in February 2025, Robert F. Kennedy was appointed United States Secretary of Health. Kennedy is a well-known anti-vaccine activist who for years has been a highly active detractor of the measles vaccine and, of course, also of the Human Papillomavirus (HPV) vaccine. He was appointed Secretary of Health despite the fact that more than 75 Nobel Prize laureates unsuccessfully urged the United States Senate not to confirm him in this position.

Recently, Robert F. Kennedy dismissed all 17 members of the United States scientific vaccine committee. The consequences of this unprecedented event remain to be seen, although, beyond the impact in the United States, it will evidently have major repercussions worldwide. The composition of the newly appointed committee of eight members does not suggest a promising future.

The world of the anti-vaccine movement operates within complex mental frameworks, in esoteric and conspiratorial contexts that frequently include flat-earth beliefs, climate change denialism, and followers of so-called “alternative medicines” such as homeopathy, acupuncture, herbal medicine, and mind-body therapies, among others. They are neither “medicines” nor “alternatives.”

Analyzing and understanding how these mental frameworks are established and consolidated is both urgent and extremely complex. It requires the participation of sociologists, psychologists, communication experts, and many other professionals, in addition, of course, to civil society itself.

Anti-vaccine groups and other forms of denialism are highly active and make extensive use of social media, which has become extremely useful for spreading all these “ideas” — let us call them “ideas.” These “ideas,” naturally, lack any scientific basis, yet they are highly skilled at manipulating emotions and fostering a sense of rebellion against “the establishment,” a powerful mechanism in the consolidation of these groups.

The distancing of certain sectors of the population from vaccines is, paradoxically, a collateral effect of the success of vaccines over the last 50–70 years — a case of becoming a victim of one’s own success. There is a tendency to attribute to vaccines any health problem that merely occurs temporally after vaccination, assuming that “sequence implies consequence” (post hoc ergo propter hoc). This is a type of fallacy, described long ago, which assumes that if one event occurs after another, the second event must necessarily be caused by the first.

At the same time that this phenomenon occurs, the immense benefits of vaccines become intangible and go unnoticed by broad sectors of the population — precisely those most vulnerable to anti-vaccine movements.

Therapeutic cancer vaccines are gaining increasing prominence. What do they consist of, and where are clinical trials heading in this field?

The so-called “therapeutic cancer vaccines” act against an already existing cancer by stimulating the immune response against cancer cells. These cancer cells contain on their surface elements that act as antigens, and the vaccines are specifically designed to target these antigens and destroy the cancer cells.

Are these personalized vaccines?

They are personalized vaccines, tailored specifically to each patient. At least for the moment, they appear to be effective for certain types of cancer.

There are different types of these therapeutic vaccines: cell-based vaccines, DNA-based vaccines, RNA-based vaccines, as well as vaccines based on proteins, peptides, or vectors, among others, all with different mechanisms of action. It is truly a complex field.

To what extent are these vaccines already part of oncological treatment?

The development and use of these so-called “therapeutic vaccines” is still at a very early stage. They are already being used for certain prostate cancers and melanomas, and are currently in clinical trial stages for breast, lung, and colon tumors.

Chagas disease is still waiting for its vaccine. What advances are being made in vaccinology, both preventive and therapeutic?

Trypanosoma cruzi is a parasite responsible for Chagas disease, which primarily affects different regions of Argentina, Bolivia, Mexico, and Brazil. It is transmitted mainly through the bite of triatomine insect vectors found in these geographical areas, although transmission from mother to child during childbirth is also possible, as well as transmission through blood transfusions or transplants involving uncontrolled blood or organs. Foodborne transmission has also been described.

At present, there is no approved preventive or therapeutic vaccine against Chagas disease. However, advanced studies are underway involving therapeutic vaccines designed to prevent the cardiac complications of the chronic phase of the disease, such as the CRUZIVAX project, as well as other therapeutic vaccines based on nucleic acids (DNA and RNA) encoding a synthetic protein known as Traspaine. These approaches are being studied both as monotherapy — meaning the use of this therapeutic vaccine alone — and in combination with a widely used antiparasitic drug, benznidazole.

At present, preventive strategies are therefore focused on vector control, improving housing conditions that serve as nesting sites for these insect vectors, screening blood and organ donations, and, of course, the early diagnosis of newborns from infected mothers.

COVID-19: what challenges lie ahead for global immunization against this disease?

Vaccination against COVID-19 began on December 8, 2020. Between December 8, 2020, and December 8, 2021 — the first year of vaccination — it is estimated that COVID-19 vaccines prevented 14.4 million deaths across 185 countries and territories. This estimate rises to approximately 20 million deaths prevented when compared with the excess mortality observed during the previous year, which provides a more accurate estimate of the true magnitude of the pandemic and the impact of vaccination. This represents a 63% global reduction in total deaths during the first year of vaccination alone.

How many types of coronavirus exist?

We currently know of seven types of coronavirus that affect humans. The first four cause the common cold, a disease also produced by different agents such as rhinoviruses, adenoviruses, and the respiratory syncytial virus (RSV), among others.

In 2002, a new coronavirus appeared in a region of China: SARS-CoV, which had a much greater pathogenic capacity and was responsible for Severe Acute Respiratory Syndrome (SARS). It primarily affected regions of Asia, although it also spread to around 30 countries outside the region. A total of 8,400 cases and 800 deaths were recorded, representing a mortality rate of 10%. This virus circulated for only three years: 2002, 2003, and 2004.

In 2012, MERS-CoV emerged, another new coronavirus that infected camels and caused severe disease in regions of the Middle East. In humans, it caused Middle East Respiratory Syndrome (MERS). It circulated for only a couple of years, producing 2,500 cases and 850 deaths, representing an extremely high mortality rate of 35%. This coronavirus has also not shown signs of renewed activity.

The third new coronavirus is SARS-CoV-2, which appeared at the end of 2019 and spread during the following years. Unlike its close relatives, SARS-CoV-2 has come to stay.

What are the challenges for global immunization against SARS-CoV-2?

As for the challenges of achieving global immunization against this disease, the first and most obvious is improving universal and equitable access to these vaccines. Although vaccination campaigns have been extensive worldwide, inequalities in vaccination coverage have persisted. For this reason, the COVAX initiative (COVID-19 Vaccines Global Access Facility) was created with the aim of providing special support to lower-income countries in order to improve vaccination coverage.

SARS-CoV-2 has lost pathogenic power thanks to vaccination and, naturally, also thanks to natural infection. However, I insist that it is here to stay. Therefore, it is essential to continue monitoring new variants, since vaccines will need to be adapted to emerging subtypes. It is also necessary to continue developing and implementing specific vaccination and revaccination programs for people at greater risk of complications. This higher risk depends on factors such as age, immunosuppression, immune deficiency, pregnancy, and others. The objective is to protect the most vulnerable groups, whatever the reason may be. 

You are one of the leading experts on the Human Papillomavirus (HPV) vaccine, a pharmaceutical product designed to reduce HPV infection and decrease its most aggressive consequences, such as cervical cancer. What exactly does this vaccine consist of?

Around 150 types of papillomavirus are known to cause different pathologies in various animal species. In humans, approximately 12 types — including 16, 18, and others — are responsible for different neoplasms. In addition to cervical cancer, oncogenic HPV types are also responsible for cancers of the vagina, vulva, anus, penis, and oropharynx.

Other HPV types, specifically 6 and 11, cause anogenital warts.

Persistent infection of the genital tract is a necessary, although not sufficient, condition for the development of cervical cancer, because other factors must also be present for the disease to develop. What is clear is that without the virus, there is no cancer. Therefore, vaccination represents an extraordinarily powerful preventive tool.

HPV vaccines use the structural proteins of the capsid — L1 — obtained through genetic recombination technology from baker’s and brewer’s yeast, scientifically known as Saccharomyces cerevisiae. They are also obtained from baculoviruses, viruses that primarily infect a species of moth known as Trichoplusia ni.

The recombinant L1 proteins obtained in this way have the property of self-assembling into particles known as VLPs (virus-like particles). These VLPs, which are free of DNA, are morphologically and antigenically similar to the “real” HPV, to such an extent that — if I may use the expression — they deceive the immune system.

What is the efficacy and safety level of these vaccines?

The efficacy and safety of HPV vaccines, although already demonstrated in the pivotal clinical trials that paved the way for vaccine authorization, have also been confirmed in real-world conditions after the administration of more than 270 million doses worldwide.

In terms of HPV vaccine research, where do we currently stand?

Current research is focused on further improving the vaccines themselves, including additional HPV types, better understanding the role of adjuvants in achieving cross-protection against virus types not included in the vaccine, developing new vaccination strategies, and, of course, expanding vaccination to population groups that are still not adequately protected. These include males, people at greater risk of infection or complications, as well as communities and geographical areas with fewer resources, where achieving high vaccination coverage remains more difficult.

All of this takes place within the broader objective of improving information provided both to the general population and to healthcare professionals regarding the importance of HPV vaccination. We must work not only at the population level in general, but also to improve awareness among healthcare professionals who do not work directly with vaccines about the importance of these pharmaceutical products in the prevention of HPV-related diseases.

When should this vaccine be administered?

As part of routine vaccination, it should ideally be administered at 11–12 years of age to both girls and boys, although priority should be given to girls if resources limit or make it difficult to vaccinate individuals of both sexes. In any case, the vaccine is authorized from the age of 9 years onward.

At least 57 countries, following the recommendation issued by the WHO in 2022, already use a single-dose schedulewhen vaccination is administered between the ages of 9 and 14 years. From the age of 15 years onward, two doses separated by an interval of six months are recommended. Alternatively, a three-dose schedule may be used, with the first two doses separated by one or two months and the third dose administered six months later.

What are the HPV vaccination requirements for non-immunocompetent populations?

When vaccinating individuals who are not immunocompetent, regardless of the age of the vaccinated person, the three-dose schedule must be used.

Of course, whenever possible, adolescents who were not vaccinated at the appropriate time for any reason can and should be vaccinated through catch-up vaccination programs. Likewise, sexually active individuals, who are therefore at risk of exposure to HPV, should also be vaccinated whenever possible.

Why were HPV vaccination recommendations initially introduced for girls?

The first vaccination recommendations and strategies focused on girls because they were the population expected to bear the greatest burden of the disease. However, it is extremely important to emphasize that the vaccination of boys, adolescents, and men — in addition to providing direct protection to the vaccinated individual — also contributes to herd immunity, since it reduces the risk of transmission to their sexual partners, whether women, men, or both.

Once an HPV-related lesion has developed, do these vaccines have a therapeutic effect?

No. These are preventive vaccines and do not modify the course of a pre-existing lesion.

The importance of early childhood vaccination, before the onset of sexual activity, is based precisely on this greater preventive potential — that is, when there is an almost absolute guarantee that no contact with the virus has yet occurred. Furthermore, vaccination at this stage achieves optimal and significantly higher immune responses, thereby reducing the number of doses required.

What is the real-world effectiveness of the HPV vaccine in women?

Efficacy is measured under ideal conditions; this is what clinical trials study and determine. Effectiveness is measured under real-world conditions, that is, when the vaccine is marketed and administered in everyday life. Effectiveness is therefore assessed in population-based studies, where the intervals between doses have not always been entirely correct and where not all individuals are always in optimal conditions to achieve the best response.

In women aged 9 to 26 years, efficacy against infection, measured in clinical trials, is well above 95%, and efficacy is 90–100% against high-grade precancerous lesions (CIN2+) caused by types included in the vaccine.

Population-based studies conducted in Sweden and England have found an 87% reduction in cervical cancer among women who were vaccinated before the age of 17.

In men, efficacy is 90% against genital warts, with a 75% reduction in infections and anal precancerous lesions.

What reference studies do we have on the effectiveness of the HPV vaccine?

Effectiveness has been studied in different countries. Australia is a very exemplary country in this regard because it began vaccinating girls in 2007 and boys in 2013. It also implemented a very ambitious program that included the entire population between 9 and 25 years of age: girls and boys, women and men.

In this way, a 90% reduction in genital warts among young women has been observed, as well as an 87% reduction in infections caused by types included in the vaccine, a 47% decrease in high-grade cervical lesions (CIN2+) in those under 20 years of age, and a 70% decrease in invasive cervical cancer.

In Scotland, reductions of 89% have also been found in high-grade cervical lesions, specifically CIN3 precancerous lesions.

It is also very good news, of course, to confirm that after 10–12 years of HPV vaccination, high levels of protection are maintained.

The HPV vaccine has been questioned on numerous occasions and in many contexts. What explains this?

Since Jenner’s smallpox vaccine at the dawn of the 19th century, there have always been vaccine detractors. And let us remember the persistent harassment of the measles vaccine in the wake of the autism hoax triggered by Wakefield in 1998, which caused so much harm and continues to do so even now, in the United States, for example.

Conspiracy theories and the “pandemic” spread — because this truly is pandemic — of hoaxes through social mediafavor all these phenomena. Disaffection toward the HPV vaccine, and toward other vaccines, is complex and multifactorial. In 2007, when the use of these vaccines was still in its early stages, in some countries such as the United States, vaccine detractors were ultra-Catholic groups who put forward moral-religious arguments, believing that vaccinating girls would encourage them to engage in uncontrolled sexual relations. It was no longer only a health risk, but a moral-religious risk.

In Spain, speaking of this multifactorial disaffection toward vaccines, a group of healthcare professionals promoted a moratorium on HPV vaccination in 2007, 2008, and 2009. The basic argument given was that “it had not been demonstrated that vaccination prevented cervical cancer,” although safety concerns and cost-benefit reasons were also put forward. However, at that time it had already been demonstrated that the vaccine prevented incident infection, persistent infection, and precancerous lesions — stages that are absolutely essential in the natural history of the disease on the path toward cancer.

What is striking about this regrettable episode is that among the main promoters of the moratorium were healthcare professionals with high academic qualifications in various aspects of public health, although with no experience in the epidemiology, prevention, and treatment of HPV infection.

What do you think caused this rejection of scientific evidence by these healthcare professionals?

Without ruling out more complex motivations, at least in some cases, we must assume that such positions, contrary to those of the expert scientific community — emphasizing expert — must lie somewhere between a profound lack of knowledge of the natural history of the disease and a regrettable desire for prominence.

Expanding the use of vaccines — all vaccines — and combating inequality in this area: where do we stand today, and what global challenges lie ahead?

We have already discussed the achievements made over the last 50 years with vaccines, as well as with COVID-19 vaccination. Obviously, many tasks remain pending. No fewer than 20 million children worldwide fail to receive even the basic three-dose DTP vaccination each year (Diphtheria, Tetanus, Pertussis). The African region accounts for half of these cases, followed by Southeast Asia and the Eastern Mediterranean. COVID vaccination, although successful, has involved major differences between WHO regions.

In 2000, GAVI was created. The Global Alliance for Vaccines and Immunization is a public-private partnership dedicated to increasing access to vaccines for children in the poorest countries. GAVI’s objectives are to increase equitable access to vaccines, protect child health in low-income countries, and strengthen health systems and the sustainability of vaccination programs. Members of GAVI include the WHO, UNICEF, the World Bank, various NGOs, vaccine manufacturers that act as donors by offering reduced prices, and different governments; around 57 governmentsworldwide are GAVI donors. The United Kingdom, the United States, and Norway are the three main donors. Spain has been a donor since 2006.

In terms of donations, the United States would be the third donor. There is some concern that this may change, because President Trump recently eliminated the United States Agency for International Development (USAID), an agency responsible for managing economic and humanitarian assistance worldwide. At present, the United States has not denied its participation in GAVI, but there is concern that there may be a change of direction in this regard, given the very strange things happening in that country.

Private donors also include the Bill & Melinda Gates Foundation, which was one of the founders and has been, and continues to be, one of the largest funders. The Rockefeller Foundation, pharmaceutical companies, and technology companies are also involved.

As for beneficiary countries, there are 70 low-income or lower-middle-income countries, mainly in Africa and Asia. This is reviewed periodically, and there may be slight variations over the years.

Over these 25 years, GAVI has contributed significantly to improving vaccination coverage worldwide, although, evidently, much work remains to be done. In 2020, COVAX, the COVID-19 Vaccines Global Access Facility, was created. It is an alliance driven by public and private actors with the objective of guaranteeing equitable access to vaccines. More than 190 countries participate in COVAX as donors. Spain’s contribution has been especially notable in this regard, as it is among the five largest donors in the world, having contributed more than 50 million COVID vaccine doses and more than 220 million euros, partly through COVAX and partly through GAVI.

In terms of communication and public outreach, what would you recommend? How can we communicate effectively and responsibly?

In 2019, the World Health Organization (WHO) identified what it considered to be the 10 greatest threats to global health. Among them was — and still is — the risk of an influenza pandemic. At least six of these threats referred to communicable diseases, whether preventable through vaccination or not.

What I am especially interested in highlighting among these ten threats is what was described as “vaccine hesitancy”, defined as the reluctance or refusal to vaccinate despite the availability of vaccines and vaccination services. The causes of vaccine hesitancy are many; it is a multifactorial phenomenon, and therefore the approach to addressing the problem must also be multifactorial.

One important aspect is listening to the reasons expressed by those who oppose vaccination, because in many cases they are not active detractors but individuals who fear side effects — fears that may sometimes have some basis and often none at all. There is also the belief that vaccines are unnecessary because they do not know of any cases of disease, they cannot distinguish one disease from another, or because of claims that vaccines are part of a dishonest business driven by manufacturers, among many other arguments.

It is also important to identify the groups promoting rejection of vaccination and their motivations. We should try to use simple arguments and messages, rather than exhaustive scientific explanations, because the audience may lose track of the message during overly complex explanations. It is useful to resort to anecdotes and specific cases. And perhaps it is also important to avoid spokespersons who could, in some way, encourage rejection.

Information and health education regarding the benefits and safety of vaccines are extremely important and can — and should — be developed in many settings, such as schools, patient associations, and, of course, social media itself. Ultimately, the objective is to foster alliances with civil society.

It is also important to monitor the sources of hoaxes and misinformation in the written press, digital media, television, and elsewhere, in order to respond accordingly.

Continuous training of healthcare professionals is equally important — both for those directly involved in vaccination and for those who are not — because the position taken by healthcare professionals will evidently be extremely valuable in achieving greater adherence to vaccination.

Of course, access to vaccination centers should also be facilitated in terms of opening hours, appointments, and accessibility in general — in short, making things easier. And, naturally, transparent information should always be provided as early as possible regarding warning signals or news, whether true or false, that may reach the public concerning the safety and efficacy of vaccines.

Dr. Bayas, could we say that vaccines save lives?

That is precisely what we have been discussing throughout this conversation. To conclude, I would simply quote Stanley Plotkin, surely the most distinguished living vaccinologist, to whom the following statement is attributed:

“After clean drinking water, vaccines are the advance that has contributed the most to saving lives and increasing life expectancy.”