Why are vaccines irreplaceable in the age of planetary health?

The pandemic triggered by the outbreak of SARS-CoV-2 has put the focus once again on the importance of vaccination as a preventive strategy against a significant number of diseases. It has also highlighted the impact of the same disease spreading worldwide, which has led many experts to talk of a planetary health crisis, with causes that it is important to know, control and prevent.

To analyse these issues, the UOC's Faculty of Health Sciences has organized a seminar on vaccination in the age of planetary health, which will be held on 28 October as a webinar.

One of the central themes that will be addressed is the role of vaccines in preventing the development of certain types of cancer. As Dr Xavier Bosch, adjunct professor at the UOC's Faculty of Health Sciences and emeritus consultant at the Catalan Institute of Oncology (ICO), explained, some viruses can cause cancer in the long term, one of the most representative examples of this type of virus being the human papillomavirus (HPV): "HPV vaccination has already benefited over one hundred million people worldwide, most of them in developed countries, with established mechanisms for evaluation, epidemiological monitoring and vaccine safety recordkeeping. Currently, we have very consistent evidence that this vaccine effectively prevents not only infection but also the appearance of HPV-related pre-neoplastic cervical lesions. In addition, this October we have had the (long-awaited) confirmation of a nearly 90% reduction in the incidence of cancer cases in the populations of girls who were vaccinated before the age of 17".

Evidence for the HPV vaccine and "prognosis" for the coronavirus vaccine

As an indication of this vaccination's importance, the WHO has launched a campaign to eradicate cervical and uterine cancer worldwide. Its goals for 2030 are to vaccinate 90% of girls under 15; offer quality screening (HPV test) to 70% of women at 35 and 45 years of age; and adequately treat 90% of the pre-cancer and cancer cases identified in the screening.

"This is an international endeavour to mobilize interest and resources to eradicate a cancer that, just a century ago, was one of the most common cancers in the female population. Screening (regular Pap smears) reduced this tumour's incidence in developed countries, which had the resources to implement a quality population-based screening programme with wide coverage. However, for most populations, cervical cancer remains a major health problem (it is still one of the top three cancers in many countries). The incidence of HPV-associated tumours is estimated at about 700,000 cases annually, including tumours affecting the cervix, the male and female anogenital tract, and the oropharynx," explained Bosch.

As regards the expectations about the forthcoming availability of a vaccine against COVID-19, Bosch believes that interesting results will probably become available in 2021 for several of the vaccines currently under development. "Producing the vaccine on a massive scale and administering its distribution on a planetary scale will be a huge enterprise. However, the factors that incline us toward optimism are the vaccine industry's power to ramp up production capacity and the commitment by five of the largest producers to assure an initial supply of 84 million doses for the countries included in the GAVI (Global Alliance for Vaccines and Immunization) group, that is, the world's poorest countries".

The pandemic's global impact has also highlighted the importance of analysing to what extent the effects of certain human behaviours on the environment lead to the degradation of ecosystems, creating favourable conditions for the emergence of microorganisms and the spread of diseases such as COVID-19. This is an issue that is receiving growing attention, especially in contexts such as the present, and is currently the subject of planetary health studies.

Environmental damage and the proliferation of new viruses: there's a connection

As Cristina O'Callaghan Gordo, professor at the UOC's Faculty of Health Sciences and one of the experts on the subject, explained, the relationship between the status of ecosystems and pandemics such as the one we are currently suffering is governed by a number of mechanisms: "One of them is the role played by ecosystems with a high level of biodiversity in regulating pathogen transmission. It has been found that viruses such as SARS-CoV-2 are more likely to emerge and spread in areas where these ecosystems are more degraded. Another relevant aspect is the changes in food production systems, with increased contact between wildlife and humans in highly populated areas, which facilitate the emergence and global spread of new infectious diseases".

Bosch added that there are disciplines, such as animal epidemiology, that should receive more attention: "We've already had avian flu and swine flu, and also a coronavirus disease in camels and dromedaries that managed to cross the barrier and achieve human-to-human transmission."

Upon considering the level of implementation of this approach in scientific investigation, Dr Bosch said that attributing this jump between species to deforestation or climate change and being able to reverse it for the benefit of the planet's global health are highly complex issues, in which the scientific community is still taking its first steps. "And the situation is the same when we look at research into new vaccines, which involves the use of highly advanced, constantly evolving technologies. Here too, the correlations and impact on planetary health parameters have yet to be described."

On the relationship between vaccination and planetary health, which will be the central theme of her lecture during the seminar, O'Callaghan said that the most significant aspect in this regard is that "vaccines, together with other disease prevention measures, play a key role in the concept of planetary health, as they reduce the number of people treated in hospitals, which is the sector with greatest environmental impact within health systems".

The risk of the anti-vaccine message

The experts' unanimous, generalized support for vaccination for combatting both COVID-19 and the other diseases that can be prevented by vaccination contrasts with the actions of the anti-vaccine movements, which have used the current situation as a platform to give increased visibility to their messages. "Fortunately, these are minority groups. However, they are very active in the social media, where their fake news can wreak havoc. Where we need to tread most carefully is not with these fanatical groups but with those who have doubts (vaccine hesitancy) about the necessity or advisability of vaccinating themselves or their children or their aged relatives. These opinion groups can end up being swept along by the inertia of the anti-vaccine messages," warned Bosch.

This expert also pointed out that when vaccination (or other health indications) is taken to the political arena and political parties use it to back their arguments in one direction or another, it is easy for the population to lose sight of the information and be swayed by the deluge of opinions. "COVID-19 is showing us every day just how far the situation can go. It is not easy to maintain a critical spirit when the prevailing atmosphere is one of uncertainty about the future. That is why it is important to filter the information generated through the screen of science and scientific rigour; we must distinguish between opinion and information and rely on the latter when making decisions," said Bosch.