Determinants of COVID-19 Vaccination Worldwide: WORLDCOV, a Retrospective Observational Study

The COVID-19 pandemic has had major health, economic and social implications, bringing with it a large number of deaths worldwide. While the lethality rate could not be considered high, the fact that the contagiousness was high resulted in a considerable number of deaths. As a result, the COVID-19 pandemic has become a sudden, huge and urgent public health problem.

Initially faced with a new and unknown etiopathological entity, different countries adopted different policies that proved more or less effective in containing the COVID-19 contagion. While social and hygienic restrictive measures (i.e. so-called social distancing, curfews, use of masks and hand hygiene) initially had a positive impact on reducing infections, for the most part they proved to be ephemeral measures. These actions were short-lived because they were not sustainable over time due to the damage they implied with regard to mental health, besides the low adherence of the population. A relaxation of these restrictive measures has always led to an increase in the spread of the COVID-19 pandemic, with a resurgence of hospital admissions, an ever-increasing occupancy of intensive care beds and a subsequent increase in the number of deaths.

Since the beginning of the COVID-19 pandemic, scientific research has been working to enable the identification of the SARS-CoV-2 viral genome and possible target proteins for treatment. Due to years of vaccine research and the launch of Access to COVID-19 Tools (ACT)-Accelerator partnership, a rapid development of several candidate vaccines based on different vaccine technologies and thus to their rapid clinical testing were possible.

Thanks also to the regulatory agencies' solicitude, in certain Countries (e.g. Israel, the UK, the US and the EU) the COVID-19 vaccination campaign started at the end of 2020 and extended worldwide during 2021 (with the exception of Eritrea and the Democratic Republic of Korea).

Through purchasing agreements with individual vaccine manufacturers, governments (or supranational institutions, e.g. the EU) secured the supply of the necessary doses. However, this entailed a division of the world's population depending on the negotiating power of the country of residence and, therefore, its economic strength. COVAX is one of the three pillars of the ACT-Accelerator programme: dedicated to vaccines, the purpose of COVAX is to accelerate the development and manufacture of COVID-19 vaccines, ensuring fair and equitable access for every country in the world.