Each and every one of the vaccines developed against COVID-19 that are currently being inoculated around the world, have demonstrated their safety and efficacy in preventing the development of moderate and / or severe disease , thus reducing the probabilities of hospital admission, ICU and death. Regulators such as the US Food and Drug Administration (FDA) or the European Medicines Agency (EMA) have thoroughly reviewed and analyzed all data provided by manufacturers obtained through clinical trialsin which tens of thousands of people around the world have participated.
Given this photograph, we focus on a recent study carried out by the Centers for Disease Control and Prevention of the United States (CDC, for its acronym in English), through which more than 600,000 cases of COVID have been analyzed. 19 registered in 13 states in the period between April and June 2021.
As the SARS-CoV-2 Delta variant (B.1.621.2, originally detected in India) progressed, people who had not been vaccinated against COVID-19 were 4.5 times more likely to infected than those who had completed the immunization schedule. A positive fact that reinforces the growing scientific evidence regarding the protection that sera could offer in terms of infection. But the most important finding of this study refers to the fact that those people who have not been vaccinated are 10 times more likely to be hospitalized in case of Delta infection , and up to 11 times more likely to die according to data provided by the CDC .
«Vaccination works,» says Dr. Rochelle Walensky , director of the CDC, bluntly . «The conclusion is the following: we have the scientific tools we need to turn this pandemic around,» he asserted at a press conference held recently on the occasion of the presentation of the results of the investigation from the White House.
Although we are facing good news, the truth is that various studies have confirmed that the immunity generated through vaccines decreases over time . The so-called «advance cases» , those in which fully vaccinated people become infected and develop severe COVID-19, have gone from representing 14% of hospitalizations and 16% of deaths in the United States in the computation of June and July, being almost double the data recorded at the beginning of the year.
An increase that is neither surprising nor unexpected. The vaccines developed against COVID-19 are not sterilizing so they do not prevent infection but they do protect against the development of serious disease . Epidemiology experts have warned on numerous occasions that, as the percentages of the fully immunized population increase, the higher the aforementioned figures will be. Given this photograph, Walensky warned at the beginning of September that 90% of people hospitalized for COVID-19 in the United States were not vaccinated .
The CDC has also published two studies in recent weeks that suggest that the protection generated by vaccines decreases over time in older adults. One has focused on analyzing COVID-19 hospitalizations in nine states during the summer. Their findings indicate that the protection for those older than 75 years was 76% compared to the 89% average reported in the rest of adults . Experts ask for caution in the face of this type of study, since it is not clear whether this decrease is due to a reduction in immunity caused by the passage of time or to the possibility that the immune escape of the Delta variant is greater than expected.