Access to COVID-19 Vaccines Found More Relevant than Which Vaccine
Most high-income countries have secured an abundant supply of COVID-19 vaccines. However, to these researchers’ knowledge, there is no assessment of the pragmatic effectiveness of the COVID-19 vaccines used in low- and moderate-income countries.
Published by the JAMA Network on October 29, 2021, researchers conducted an Original Investigation that found a pragmatic implementation of a group of COVID-19 vaccines was associated with a dramatic reduction in documented COVID-19 infection.
As well as a decline in all-cause death and deaths temporally related to a COVID-19 diagnosis.
In a context where the debate over which vaccine to use has almost as much relevance as to how to reach a critical mass of vaccinated people effectively, ‘our results support recent observations from Brazil,’ wrote these researchers.
The experience of the small town of Serrana showed that the rapid and massive use of a vaccination campaign with drugs that have admittedly lower effectiveness in clinical trials than the vaccines used massively in Europe and the United States suggests that the priority should be on ‘access over product.’
In the experience of the city of Buenos Aires, the administration of one dose was associated with moderate prevention of documented infection. Still, it was good enough to prevent all-cause mortality and death in the proximity of a COVID-19 diagnosis.
Although the protection associated with one dose in people aged 80 years and older did not achieve a statistically significant decrease in death from COVID-19, one dose was associated with a reduction in death from all causes.
This is probably because the cause of death attribution is always a less rigorous outcome than all-cause death.
It is possible that older people dying from COVID-19 outside a hospital setting may not have been diagnosed promptly.
It is likely that in the older population, the documentation of the diagnosis was underestimated.
However, in all groups, a single dose was associated with reduced mortality in line with the finding of a reduction in documented infection.
As expected from the results of the clinical trials, a full vaccination schedule was associated with twice the prevention of diagnosed disease and a reduction of death with COVID-19 and death from all causes.
It should be noted that the outcome assessed in this study is that of documented infection and not an asymptomatic infection.
People tested and reported to the national data system overwhelmingly do so because of suspected disease based on symptoms rather than population-based screening.
The results should also be discussed from the perspective of the administration of the shortage.
Unfortunately, the number of available vaccines was insufficient to vaccinate the population aged at least 60 years with two doses.
In fact, until mid-May 2021, only about 20% of persons had two doses.
Despite this, the reduction of events with a single dose was satisfactory, supporting the thesis suggesting delaying a second dose to increase the number of people with at least one injection.
The analysis found no significant protection associated with two doses of any of the vaccines used for the prevention of death from any cause.
However, compared with the other vaccines, the BBIBP-CorV vaccine was associated with a higher risk of infection during follow-up. The reasons why two doses of BBIBP-CorV were associated with less protection against infection remain speculative.
It has been suggested that the low efficacy found in people with inactivated whole virus vaccines should not be surprising, as the chemical or physical treatment used to eliminate infectivity may be sufficiently damaging to modify immunogenicity, especially of the antigens needed to elicit cell-mediated immune responses.
For this reason, it has been postulated that up to three doses of such vaccines may even be necessary.
Additionally, it should be noted that although there was no statistically significant difference in the estimated mortality among the populations that received the different vaccines in this study, this should be evaluated prospectively with larger numbers of cases and events to verify if there is different effectiveness among these COVID-19 vaccines.
The present study only focused on analyzing population groups that had a high rate of vaccination with at least one dose.
Although the first vaccinated population in Argentina was health care workers aged 20 to 59 years, they represent a small fraction of the population and the unvaccinated groups of people of that age have an exposure and risk profile that is quite different from those vaccinated.
These differences should be smaller in the analysis presented here, as in the age group of people aged at least 60 years, people with at least 1 dose represent more than two-thirds of the total population in this age group, reaching more than 90% in those aged at least 80 years.
Study Limitations - Although analyses with ecological approximations have inherent risks owing to the lack of correction models that take into account variables associated with the unvaccinated population that may contribute to the differences between groups, the present analysis considered important information to qualify the associations between vaccination and outcomes.
No researcher conflict of interest was disclosed.
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