Progression of COVID-19 in six South American countries with different vaccination coverage

Abstract

COVID-19 seems to have progressed under two general assumptions: a) every new variant of SARS-Co V-2 should bear the worst consequences, thus justifying extension of government-mandated lock-downs, school and border closures, face mask wearing and other restrictive measures and b) that hastily developed experimental vaccines employing novel technologies would quickly and efficiently stop the pandemic by protecting from infection or, at the very least, by preventing complications and death. We tested these two hypotheses by analyzing the epidemiological data officially released by the governments of six countries in South America. We found that vaccination failed to prevent contagion by Omicron or by previous variants of SARS-Co V-2. Mortality has decreased with time since the start of global COVID-19 in early 2020 with Omicron showing the lowest mortality to date. This finding cursorily agreed with a beneficial effect of vaccination in each individual country but failed when countries with similar mortalities and different vaccination rates were analyzed. Thus, the slight but continued reduction in mortality through the duration of the pandemic and sharp decrease with Omicron do not correlate with the level of national vaccination among the countries studied. A more plausible explanation for the decrease in mortality through time is the natural attenuation of SARS-Co V-2 from successive passage through millions of susceptible and healthy hosts, as dictated by well-established principles of virology, immunology, and vaccinology dating at least from the mid 1950’s. The failure to prevent infection or to substantially reduce mortality as reported here should raise questions about the value of the massive vaccination campaigns in South America, particularly, considering the potential risks of adverse reactions (still to be fully determined) to experimental vaccines and the considerable cost to the stressed national economies of the region.