COVID-19 Case Numbers as a Function of Regional Testing Strategy, Vaccination Coverage, and Vaccine Type

Abstract

Introduction The COVID-19 pandemic that began in 2019 has become a serious challenge for humanity almost everywhere globally. Despite active vaccination around the world, prevalence in different countries varies significantly as of May 2022. The reason may be a combination of demographic, immunological, and epidemiological factors. The purpose of this study was to analyze the relationship between COVID-19 prevalence in the population and the types of SARS-CoV-2 vaccines used in different countries globally, taking into account demographic and epidemiological factors. Materials and methods An initial database was created of demographic and immunoepidemiological information about the COVID-19 situation in 104 countries, collected from published official source and repository data. The baseline included for each country: population size and density; SARS-CoV-2 testing coverage; vaccination coverage; prevalence; as well as a list of vaccines that were used, including their relative share among all vaccinations. Subsequently, the initial data set was stratified by population and vaccination coverage. The final data set was subjected to statistical processing both in general and taking into account population testing coverage. Results After formation of the final data set (including 53 countries), it turned out that reported COVID-19 case numbers correlated most strongly with testing coverage and the proportions of vaccine types used, specifically: mRNA (V1); vector (V2); peptide/protein (V3); and whole-virion/inactivated (V4). Due to the fact that an inverse correlation was found between 'reported COVID-19 case numbers' with V2, V3 and V4, these three vaccine types were also combined into one analytic group, 'non-mRNA group' vaccines (Vnmg). When the relationship between vaccine type and prevalence was examined, minimum prevalence was noted at V1:Vnmg ratios (%:%) from 0:100 to 30:70. Maximum prevalence was seen with V1:Vnmg from 80:20 to 100:0. On the other hand, we have shown that the number of reported COVID-19 cases in different countries largely depends on testing coverage. To offset this factor, countries with low and extremely high levels of testing were excluded from the data set; it was then confirmed that the largest number of reported COVID-19 cases occurred in countries with a dominance of V1 vaccines. The fewest reported cases were seen in countries with a dominance of Vnmg vaccines. Conclusion In this paper, we have shown for the first time that the level of reported COVID-19 prevalence depends not only on SARS-CoV-2 testing and vaccination coverage, which is quite logical, but also on the vaccine types used. With the same vaccination level and testing coverage, those countries that predominantly use vector and whole-virion vaccines feature prevalence that is significantly lower than countries that predominantly use mRNA vaccines.

SARS-CoV-2 collective immunity among the population of the Republic of Armenia

“…The conducted cross-sectional, randomized study showed that by mid-April 2022, the total SARS-CoV-2 seroprevalence in the Armenian population included in the study reached 98.4% (95% CI 98.1-98.7). This significantly exceeds the previously postulated threshold beyond which epidemic spread of a pathogenic virus stops [18,22]. As expected, statistics provided by global sources show that after 15/04/2022, COVID-19 incidence in the RA decreased to almost zero, manifesting only in the form of individual sporadic cases in the subsequent period [3,6,12,17].…”

“…It should also be noted that the vaccines used generated the same proportions of RBD seropositive. The reason for the noted features seems to be that inactivated vaccines contain the maximum set of viral antigens by design, unlike vector or especially mRNA preparations [22].…”

“…This is foremost due to a significant decrease in the proportion of people with an Nc antigen response (p < 0.0001). This is expected since mRNA vaccines contain only mRNA encoding spike protein antigens [22]. Naturally, there were no grounds to expect a decreased RBD antigen response (Fig.…”

“…The question stems foremost from the antigenic structure of the specific preparations. Inactivated whole-virion vaccines contain the entire spectrum of SARS-CoV-2 antigens, whereas vector and, especially, mRNA preparations contain only spike protein components or even RBD antigens [22]. With this in mind, we analyzed the structure of humoral immunity formed in response to usage of each vaccine type.…”

Evolution of Collective Sars-Cov-2 Humoral Immunity among the Population of the Republic of Belarus

“…Taking into account the previously noted effectiveness of vector vaccines [40], the widespread use of the Sputnik family of vaccines may have become a significant factor behind decreasing COVID-19 incidence in the population. Another pattern confirming such a process is the inverse relationship between population humoral immunity and morbidity: an increase in post-vaccination resistance is inevitably accompanied by a decrease in morbidity [23,[41][42][43][44][45][46].…”