Half a dose of AstraZeneca can be used as a booster, says research


Final results of a study carried out in the city of Viana (ES) indicate that half a dose of the AstraZeneca/Oxford vaccine against Covid-19 is effective and can also be used as a booster dose.

The research showed that, in the primary regimen, when the first two applications of the immunizing agent are made, the half dose had similar effectiveness to the standard dose for preventing 70% of new cases of the disease and there were no deaths and no hospitalizations after complete immunization. .

The Viana Vaccinada project is coordinated by Hucam-Ufes (Cassiano Antônio Moraes University Hospital, Federal University of Espírito Santo), which integrates the Ebserh (Brazilian Hospital Services Company) network, in partnership with Fiocruz (Oswaldo Cruz Foundation).

The results were presented to Fiocruz, which produces the AstraZeneca vaccine in Brazil, and to PAHO (Pan American Health Organization).

This Friday (21), he will be taken to Ctai (Technical Advisory Board on Immunization of Covid-19), which assists the Ministry of Health in public policies to face the pandemic.

The study also showed that the half dose was able to induce the production of neutralizing antibodies in 99.8% of the participants, a result similar to that achieved in the standard dose regimen.

In participants who had neither had Covid nor received any vaccines before, antibody production was higher than in people who took a standard dose.

In addition, observed adverse events were mild, and the overall frequency was similar at half-dose or standard-dose. However, the duration of side effects was shorter in the half-dose group.

In the study, the half-dose vaccination took place on June 13, 2021 and reached 20,685 participants, aged 18 to 49 years. The second stage of immunization was on August 8th. Viana has 80.7 thousand inhabitants.

Of the total of vaccinated, 558 were selected to be monitored with collection of blood samples to evaluate the production of neutralizing and cellular antibodies.

Valéria Valim, medical coordinator of the research, said that the studies could subsidize the health authorities of Brazil and of the world to double the capacity of immunization with the vaccine of AstraZeneca.

“The research result is being presented and it indicates that the half dose can be used as a booster dose. If the authorities have this understanding based on the research, the half dose can be inserted in the leaflet. This can expand vaccination in more countries. poor, for example,” he said.

Conep (National Research Ethics Commission), in view of the results presented, authorized the population of Viana from 18 to 49 years old to receive a half-dose booster. Those who participated in the study and also those who received a standard dose of AstraZeneca, Coronavac or Pfizer can receive half a dose.

The research was sponsored by Icepi (Capixaba Institute for Teaching, Research and Innovation in Health), of the Espírito Santo State Health Department, with the support of PAHO, the Ministry of Health and the municipal government of Viana.

Espírito Santo started another research on Friday (14) to test the effectiveness of Coronavac in children and adolescents. There will be 1,280 participants from 3 to 17 years of age.

Known as Projeto Curumim (child in Tupi), it will also check the safety and production of antibodies and defense cells in children and adolescents.

For this, participants will be divided into two groups: those who receive the Coronavac vaccine and those who receive the Pfizer vaccine. Children under 5 years old will only be immunized with the first drug.

The objective is to compare the efficacy and safety of the Coronavac vaccine in children and adolescents, based on the Pfizer immunizer.

Both vaccines are approved by Anvisa (National Health Surveillance Agency). Pfizer is open to children from 5 years old and Coronavac, for children from 6 years old.

Participants will be followed up for a year by the research team, made up of pediatricians, infectious disease specialists, pulmonologists, researchers and nurses specializing in vaccines for children and adults.


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