The appearance of vaccines in the pandemic scenario in which we find ourselves has returned part of the optimism lost during the last year. However, at the same time, other important challenges have arisen that seem to darken the horizon, related, among others, to the prioritization of the population groups to be vaccinated, the logistics of vaccination or the availability of vaccines.
Likewise, the existence of different vaccines has sown doubts among the population related mainly to their efficacy and safety and to the process followed for their authorization. All this means that we want to know what vaccines there are, which ones we will receive and what factors will influence this decision.
Covid-19 vaccine authorization process
For public health emergency reasons, the European Commission (EC) developed a strategy to favor the manufacture and distribution of vaccines against covid-19.
This has been an unprecedented worldwide effort to achieve an effective and safe vaccine in record time. It should be noted that the flexibility of the authorization process has not limited the study of its efficacy and safety. In other words, all vaccines authorized by the EC have followed a similar path in their evaluation.
The strategies to reduce time have focused on:
- Authorization by centralized procedure. It involves a single European assessment and marketing authorization valid throughout the EU.
- Rolling review tool. In other words, the efficacy, safety and quality data are evaluated as they are generated.
- Investment in the logistics required for large-scale production of the vaccine to ensure equitable access to it.
- Conditional Marketing Authorization. This is an instrument contemplated in European legislation to expedite marketing authorization in health emergencies and in the face of unmet medical needs. It occurs when the benefit to public health is greater than the uncertainty of the limitation of the available data.
Thus, the European Medicines Agency (EMEA) issued a recommendation for the European Commission (EC) to grant conditional marketing authorization for the BioNTech / Pfizer and Moderna vaccines, and recently for that of Oxford-Astra Zeneca.
- Pharmacovigilance. It is a tight post-marketing surveillance system for vaccines. Industry is required to continue to provide data from ongoing clinical trials.
What vaccines could we choose from?
Today there are several vaccines already authorized or under evaluation and / or authorization. That of Pfizer-BioNTech and Moderna have already been authorized and are being administered in Spain.
The Oxford-AstraZeneca vaccine has just been licensed in Europe. Likewise, other vaccines, such as Janssen / Johnson & Johnson, Sanofi / Pasteur / Glaxo Wellcome, CureVac and Novavax, whose negotiation is ongoing, have not yet requested authorization by the EC but have already signed a marketing contract.
At the same time, there are more than 150 vaccine candidates against covid-19 and around one in three have started clinical trials. For this reason, in the coming months we will see the range of available vaccines expanded.
Assuming the similarities and differences of the different vaccines, the important thing is that all of them are safe and have sufficient efficacy, so receiving one or the other is a less relevant aspect for the population.
Can we choose which vaccine to get?
As we have already seen, while the clinical trials are being carried out, progress has been made in the manufacture of the vaccine, given the worldwide need for doses. The supply is still complex, however. To date, the development of the vaccination campaign is having significant logistical problems related to the supply of vaccines by pharmaceutical companies, storage and transport, and with the capacity of health personnel, dedicated full time to caring for patients. covid-19.
According to the data provided, in Spain 3.44 doses / 100 people have been administered as of February 1. It is a similar figure to the rest of the countries of the European Union but lower than the figures of the United Kingdom, the United States or Israel, which now almost reaches 60 doses per 100 people.
Each country has established different mechanisms to meet the objective of mass vaccination of the population. In the case of the UK or the US, the vaccination process started a week earlier than in Europe and with fewer supply problems.
In these countries, in addition, pharmacies and other health agents have been included as community vaccination centers, which has accelerated the process.
In Spain, vaccination is focusing on the public health network. Community pharmacists have offered to contribute to the vaccination health network as a health resource used in other neighboring countries. Taking into account that in Spain there is a network of more than 22,000 pharmacies, the accessibility of these health professionals could be key to optimizing the mass vaccination process necessary in these times of pandemic.
Considering the complexity of the vaccination process, it does not make sense for each person to choose which vaccine to get. Furthermore, the potential availability of each vaccine in each of the established priority population phases is unknown.
Nor do we know which vaccines will be authorized by the EC, so the population will be vaccinated with those vaccines that are available at all times.
However, when there is sufficient availability (in the medium or long term), the health authorities will be in charge of determining the most appropriate vaccine for each population group.
For example, in Spain, the Spanish Agency for Medicines and Health Products (AEMPS) is the body that makes decisions about each vaccination process. It monitors the development of vaccines and ensures good governance and transparency in the procurement and distribution process.
Factors that will influence the decision
Taking into account the differences between existing vaccines, authorities may take into account the following factors:
- First, the preservation characteristics. In areas where conservation can be compromised, for example in rural areas, priority may be given to those vaccines that are easier to maintain.
- This is the case of the Pfizer-BioNTech and Moderna vaccines (and many others that are under development), which are based on single-stranded messenger ribonucleic acid (mRNA). They are highly efficient, but their main disadvantage is mRNA instability. This conditions their storage and complicates the logistics related to vaccination.
- Thus, the Pfizer-BioNTech vaccine must be stored at -70ºC, requiring special containers for its maintenance, and Moderna’s vaccine is stable for 30 days between 2 and 8 degrees, and at least 6 months at -20ºC.
- For its part, the AstraZeneca-University of Oxford vaccine uses another more traditional technology, based on the genetic modification of a common cold virus, with the advantage that it remains stable between 2 and 8 degrees and can be distributed using the channels already existing for other vaccines.
- Second, it is important to consider the number of doses that each vaccine requires. Those with a single dose (such as the one from Jansen / Johnson & Johnson) would be ideal for the population with difficulties in accessing the health system. For example, in developing countries where the population often lives far from health centers and access to the second dose could be difficult.
On the other hand, pharmaceutical companies must monitor the effectiveness and safety of vaccines. Likewise, they must continue to provide data from the clinical trials they have underway.
For its part, from the health authorities, the Spanish Pharmacovigilance System (coordinated by the AEMPS) has developed a specific plan for the safety surveillance of covid-19 vaccines and also participates together with 7 European countries in pharmacovigilance studies, the called project ACCESS.
The acquisition of new data will allow measures to be taken about which vaccines are effective and safe in certain population groups that have not been evaluated until now.
In the case of the AstraZeneca-Oxford vaccine, for example, most of the participants in its clinical studies were between 18 and 55 years old, so more information about the use of the vaccine in older people is expected from the studies that are being carried out.
There is also a lack of data on the use of vaccines in other populations, such as children or pregnant women. As studies progress, it will be possible to find out which vaccine is more favorable for use in these other groups.
Cost is also an important factor in decisions. The price of each dose is different. Although in emergency situations like the one we are experiencing, it is not a factor to take into account, it may be a relevant aspect when vaccination campaigns are normalized.
Finally, it is important to accept that control of the pandemic will not be achieved exclusively with the vaccine. It is necessary, as the virologist Ian Mckay has explained with the Swiss cheese model, to continue maintaining the universal prevention measures that we have been carrying out until now (cleaning hands, mask, physical distance).
It is also essential to strengthen the health systems for direct care of the sick and public health (contact tracing, isolation, quarantine) and to improve the social determinants aimed at reducing socioeconomic differences in the population, among many others.
Blanca Lumbreras Lacarra, University Professor. Preventive Medicine and Public Health Area, Miguel Hernández University and Elsa López-Pintor, Dr. in Pharmacy, teacher and researcher in Healthcare Pharmacy. Pharmacy faculty. Miguel Hernández University of Elche., Miguel Hernández University
This article was originally published on The Conversation. Read the original.
