Chilean study shows variations in the success of COVID-19 vaccines

SANTIAGO, Aug. 3 (Reuters) – Sinovac’s COVID-19 vaccine was 58.5% effective in preventing symptomatic illnesses in millions of Chileans who received it between February and July, Chilean health authorities said on Tuesday , while Pfizer’s COVID-19 vaccine was 87.7% effective and AstraZeneca’s was 68.7% effective.

The data came from the latest “real world” data released by Chilean authorities on the effectiveness among its population of a series of COVID-19 vaccines.

Chile launched one of the world’s fastest COVID-19 vaccination campaigns in December, having now fully vaccinated over 60% of its population, primarily with Sinovac’s CoronaVac (SVA.O).

This vaccine was 86% effective in preventing hospitalizations, 89.7% effective in preventing admission to intensive care units and 86% effective in preventing deaths among the population between February and July, the report said on Tuesday. health official, Dr Rafael Araos, at a press conference.

In April, the same study found that CoronaVac was 67% effective in preventing symptomatic illness, 85% in preventing hospitalizations, and 80% in preventing death, suggesting that its ability to prevent the most severe impacts of the virus has strengthened, while its ability to stop symptomatic disease has diminished.

Araos said a reduction in vaccine protection was inevitable over time, especially with the arrival and increasing prevalence of more virulent strains such as the Delta variant.

“If Delta becomes more prevalent and the vaccine has a weaker response, we might see a faster drop (in efficacy),” he said, adding his voice to calls for a third dose to be issued. reminder.

The government has also released data on the efficacy of other vaccines administered in Chile, manufactured by Pfizer BioNTech (PFE.N), (22UAy.DE) and AstraZeneca (AZN.L).

Pfizer’s vaccine was 87.7% effective in preventing symptomatic COVID-19 during the same period, 98% effective in preventing ICU admission, and 100% effective in preventing death, Araos said.

AstraZeneca was 68.7% effective in preventing symptomatic COVID-19 during the same period, 98% effective in preventing intensive care admissions and 100% effective in preventing death, Araos said.

The Chile study looked at vaccine effectiveness among different cohorts of people who received two doses of the specified vaccine, partial doses of the vaccine, or no vaccine at all.

The CoronaVac part of the study looked at a group of 8.6 million people, the Pfizer BioNTech part looked at a group of 4.5 million people, and the AstraZeneca part looked at a group of 2.3 million people.

Reporting by Aislinn Laing and Fabian Cambero Editing by Chris Reese and Marguerita Choy

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