People with a full vaccination scheme are five times less likely to become ill with covid-19, 10 times less risk of being hospitalized and 11 times less risk of dying compared to those who have not been inoculated against this disease.
These are the conclusions of a report from the United States Center for Disease Control (CDC, for its acronym in English) released this Friday afternoon.
“Vaccines continue to provide strong protection against most people against hospitalization and death, even with the emergence and spread of the delta variant,” Rochelle Walensky, director of the CDC, told a news conference.
“In short: we have the tools to lower the burden of this pandemic,” he added.
This analysis took the three vaccines used in the United States: Pfizer’s, Moderna’s, and Johnson & Johnson’s. In our country, the first drug is the one most used to inoculate the population.
To reach these conclusions, the scientists analyzed the records of 615,454 people from 13 states who had fallen ill between April and July 2021, dates on which the delta variant was present. By the end of the analysis period, delta already accounted for 90% of infections.
During this period, 37,948 infected patients were hospitalized (6.17% of the cases) and 6,748 died (1.1%).
When the scientists separated the cases between vaccinated with the complete scheme and those not vaccinated or with incomplete scheme they saw these numbers.
In those who had not completed their scheme, those infected were 569,142 (92.48% of the total patients included in the study), 34,972 hospitalized (92.17% of cases) and 6,132 (90.87%) died .
In those who did complete it, there were 46,312 infections (7.52% of the total), 2,976 hospitalizations (7.83%) and 616 deaths (9.13%).
When they looked at the chances of getting sick, hospitalized and dying between people with full immunization and those who did not, the risk of getting sick was 4.6 times lower in those who had their full schedule.
In addition, the probabilities of hospitalization were 10.4 times lower in those vaccinated, and those of dying were 11.3 times lower.
The role of the delta variant
The delta variant could have an influence on the vaccine increasing cases. In April, the protection for those who had a complete vaccination was 11.1 times greater than for those who were not vaccinated or with an incomplete schedule. In July the protection was already 4.6 times higher.
However, this decrease in effectiveness was not seen for hospitalizations or deaths.
“As of July 20, with a greater predominance of the delta variant, the cases, hospitalizations and deaths of people who were not fully vaccinated rose weekly. Among people with a complete scheme, the cases did increase, but the proportions of hospitalizations and deaths remained without major changes, ”the report cites.
During this time, the protection against hospitalization and death did decrease, but not dramatically.In the opinion of the specialists, the protection against hospitalization went from 13.3 times lower risk compared to the unvaccinated to 10.4 and 16, 6 higher protection against death to 10.4.
Older adults with less protection
When compared by age, hospitalizations and deaths were more frequent in older adults.
This is consistent with what was seen in another CDC study also released this Thursday. In general, complete vaccination protected from reaching the hospital by 86.8%. However, when looked at by age, the protection was 95% for those between 18 and 64 years old, but it was 76% for those who were 65 years or older.
In a third study, 32,687 internments in 187 hospital centers were explored and lower protection was also seen for people older than 75 years, of 82% compared to 90% in the youngest.
However, both the researchers of these studies and the authorities of the CDC indicate that it continues to be a high protection for these people, who due to the aging of their immune system could react less robustly to the benefits of vaccines.
Some countries, including Costa Rica, consider adding an additional dose to older adults.
Comparison between vaccines
One of the studies also carried out an effectiveness comparison between the three vaccines. In them the efficacy of Moderna’s vaccine was 95% to protect against internments, that of Pfizer & BioNTech was 80% and that of Johnson & Johnson 60%.
The report does not state the reasons why Moderna’s vaccine is more effective. This product is not administered in Costa Rica.
The American newspaper The Washington Post give some possible ideas. One of them is that the dose of messenger RNA (the basis for the functioning of Pfizer and Moderna biologics) is three times higher in Moderna’s product than in Pfizer’s.
Another possible reason is that the interval between doses is longer in Moderna’s (four weeks between doses, versus three in Pfizer); having longer periods between doses sometimes increases the generation of antibodies.