The central role of vaccines in fighting major diseases during human history is undeniable. Effective and continued campaigns worldwide were responsible for keeping some serious and deadly diseases – like mumps, measles, polio, chickenpox among many others – under control and even eradicated some of them thanks to the ever-evolving research and development of vaccines and successful global vaccination campaigns.
The vaccination supposedly aims to protect safely people against harmful diseases as it teaches the immune system how to recognize bacterium, viruses, or pieces of viruses, (called antigens) by tricking the body to respond to a weaker pathogen present in the vaccine, helping the body to build resistance to specific infections2. This response called immunological memory enables the body to produce antibodies for that specific antigen and have a more efficient and rapid response in the case of a real infection.
The massive investment in research and global consensus to join efforts since the beginning of the outbreak prompted the rapid development of viable vaccines. This was undoubtedly a significant advance in the fight against the COVID-19 pandemic. Almost two years after the World Health Organization (WHO) official declaration of the pandemic, several vaccines have been either approved, authorized, licensed or granted emergency use authorization by different health agencies around the world. Thus far, the most widely accepted vaccines3 around the globe are AstraZeneca (used in 184 countries),* Pfizer-BioNTech (used in 150 countries), Sinopharm – Beijing (used in 86 countries), Moderna (used in 82 countries) and, Janssen – Jonhson&Jonhson (used in 77 countries).
The different types of COVID-19 vaccines work in different ways showing the potential to enhance protection against the SARS-CoV-2 virus, however, the effectiveness may vary, especially concerning the new variants of the virus. There are three main approaches to designing a vaccine.4 Their differences lie in whether they use i) a whole virus or bacterium (Inactivated vaccine and viral vector vaccine) ii) only the parts of the virus that trigger the immune system or iii) just the genetic material (DNA and mRNA vaccines) that provides the instructions to make specific proteins.
Both Pfizer-BioNTech and Moderna are messenger RNA (mRNA) vaccines which means that they contain viral genetic material providing instructions to produce viral proteins. The Oxford-AstraZeneca and Janssen – Jonhson&Jonhson are non-replicating viral vector vaccines, which means that they contain viral genetic material packaged inside another harmless virus that cannot copy itself. Finally, different from the other types the component viral vaccines, the Sinopharm – Beijing, is a whole virus vaccine made from an inactivated virus. That means that it contains dead (inactivated) copies of the virus5.
The global vaccination started by the end of 2020 and as of March 2022 – according to statistics from Our World in Data – 63 percent of the world population has received at least one dose of a COVID-19 vaccine with more than 10,84 billion doses administered globally. However, there is a clear inequity in the distribution of doses among the countries and global regions which can jeopardize the agenda of a whole global immunization process.
The inequality in the access and distribution of shots is evident and worrisome as only 13 percent of the population in low-income countries have received at least one dose against 78 percent in high-income countries. Of the global regions, Africa is far behind the average with only 17 percent of its population vaccinated with at least one dose against 77 percent in U.S. and Canada and 68 percent in Europe. The equitable doses distribution is not only a matter of fairness but it is critical for successful control of the pandemic considering that only with a fast pace and large-scale immunization coverage it is possible to detain the rise of new more infectious and potentially deadlier variants of the COVID-19 virus.
The main scientific concern at this point of the pandemic is the emergence of vaccine-resistant strains. According to a paper published recently in Nature“ A potential cause of concern is the low rate of vaccine production and administration coupled with reports of new strains with higher transmission rates and even with potential for some degree of vaccine resistance”. Although the evidence on the effectiveness of the vaccination itself depends on further data analysis, the findings of the paper suggested the importance of a broader and faster global vaccination campaign to control the emergence of new variants.
Another interesting finding from this same paper is the role of non-pharmaceutical interventions. According to the study, even when a large part of the population has already been vaccinated but there is a lack of observance of the other measures to contain the spread of the virus (such as social distancing, hygiene practices, use of masks, and avoiding crowded or indoor settings) the probability of emergence of a resistant strain increases greatly. Therefore, these results suggest that policymakers and individuals should keep hygiene behaviours and social distancing measures even after being vaccinated in order to collaborate to interrupt the virus circulation, while some studies suggest that the vaccines may play a crucial role in global immunization, it remains imperative to follow the recommended preventive measures to control the spread of the SARS-CoV-2 virus.
Disclaimer: The goal of this article is to present facts from credible sources unaffiliated with industries. It does not replace professional consultation with medical specialists. Guidelines on COVID-19 vaccines are quickly evolving, so seek professional advice for up-to-date information when making personal choices. The author declares no conflict of interest, bias, or personal views.