Contribution of Two-Dose Vaccination Toward the Reduction of COVID-19 Cases, ICU Hospitalizations and Deaths in Chile Assessed Through Explanatory Generalized Additive Models for Location, Scale, and Shape

Abstract

ObjectivesTo assess the impact of the initial two-dose-schedule mass vaccination campaign in Chile toward reducing adverse epidemiological outcomes due to SARS-CoV-2 infection.MethodsPublicly available epidemiological data ranging from 3 February 2021 to 30 September 2021 were used to construct GAMLSS models that explain the beneficial effect of up to two doses of vaccination on the following COVID-19-related outcomes: new cases per day, daily active cases, daily occupied ICU beds and daily deaths.ResultsAdministered first and second vaccine doses, and the statistical interaction between the two, are strong, statistically significant predictors for COVID-19-related new cases per day (R2 = 0.847), daily active cases (R2 = 0.903), ICU hospitalizations (R2 = 0.767), and deaths (R2 = 0.827).ConclusionOur models stress the importance of completing vaccination schedules to reduce the adverse outcomes during the pandemic. Future work will continue to assess the influence of vaccines, including booster doses, as the pandemic progresses, and new variants emerge.Policy ImplicationsThis work highlights the importance of attaining full (two-dose) vaccination status and reinforces the notion that a second dose provides increased non-additive protection. The trends we observed may also support the inclusion of booster doses in vaccination plans. These insights could contribute to guiding other countries in their vaccination campaigns.

Pathophysiological, immunological, and inflammatory features of long COVID

“…One of these studies, conducted using the US Department of Veteran Affairs healthcare database with substantial sample size, provides robust evidence that vaccination’s impact in reducing the incidence of long COVID is partial ( 82 ). Available data conclusively demonstrate that vaccines diminish the risk of long COVID by decreasing the likelihood of experiencing a SARS-CoV-2 infection ( 84 , 87 , 90 ). Other studies have shown an almost complete reduction of long COVID symptoms after vaccination, mainly for severe manifestations like fatigue ( 93 , 94 ).…”

Humoral and cellular response induced by a second booster of an inactivated SARS-CoV-2 vaccine in adults

“… 3 Due to their novelty, mRNA vaccines (BNT162b2 and mRNA-1273) have been the most studied and are highly effective in protecting individuals from symptomatic infection, severe disease, and death. 4 , 5 Inactivated virus-based vaccine, a more traditional vaccine platform, has also been used to develop a SARS-CoV-2 vaccine. CoronaVac®, an inactivated vaccine developed by Sinovac Life Sciences Co., Ltd. (Beijing, China), 6 has been administered so far in 52 countries, 7 showing a good safety profile in the population 8 , 9 , 10 and a robust immune protection against severe disease, hospitalization, and death.…”

Statistical explanation of the protective effect of four COVID-19 vaccine doses in the general population

“…Chile has been one of the countries with the highest rates of vaccination against SARS-CoV-2 and, currently, 79.9% of this population has received a second booster ( 18 ). Previously, we built a model that explained the behavior of the pandemic data as a function of the vaccination, which at that time consisted of only two doses, and gave a central role to the number of doses administered and the interaction between these two doses ( 19 ). The hypothesis of this work is that the total number of doses of SARS-CoV-2 vaccine administered to the Chilean population contributed to the control of the pandemic.…”