(Adds data on Pfizer and AstraZeneca vaccinations issued in
Chile)
By Aislinn Laing and Fabian Cambero
SANTIAGO, Aug 3 (Reuters) - Sinovac's COVID-19 vaccine was
58.5% effective in preventing symptomatic illness among millions
of Chileans who received it between February and July, the
Chilean health authorities said on Tuesday, while Pfizer's
COVID-19 shot was 87.7% effective and AstraZeneca's was 68.7%
effective.
The data came in the latest "real world" data published by
the Chilean authorities into the effectiveness among its
population of a raft of COVID-19 vaccines.
Chile began one of the world's fastest inoculation campaigns
against COVID-19 in December, having now fully vaccinated more
than 60% of its population, predominantly with Sinovac's
CoronaVac.
That vaccine was 86% effective in preventing
hospitalization, 89.7% effective in preventing admission to
intensive care units and 86% effective in preventing deaths
within the population between February and July, health official
Dr Rafael Araos said in a press conference on Tuesday.
In April, the same study found that CoronaVac was 67%
effective in preventing symptomatic illness, 85% effective in
preventing hospitalizations and 80% effective in preventing
deaths, suggesting its capacity to prevent the more serious
impacts of the virus has strengthened, while its capacity to
stop symptomatic illness diminished.
Araos said a reduction in protection from vaccines was
inevitable over time, particularly with the arrival and growing
prevalence of more virulent strains such as the Delta variant.
"If Delta becomes more prevalent and the vaccine has a
weaker response, we could observe a faster fall (in
effectiveness)," he said, adding his voice to calls for a third,
booster dose to be issued.
The government also published data on the effectiveness of
other vaccines administered in Chile, made by Pfizer BioNTech
and AstraZeneca.
Pfizer's vaccine was 87.7% effective in preventing
symptomatic COVID-19 in the same period, 98% effective in
preventing intensive care admission and 100% effective in
preventing death, Araos said.
AstraZeneca's was 68.7% effective in preventing symptomatic
COVID-19 in the same period, 98% effective in preventing
intensive care admissions and 100% effective in preventing
death, Araos said.
Chile's study examined the vaccines' effectiveness among
different cohorts of people who either received two doses of the
specified vaccine, partial doses of the vaccine or no vaccine at
all.
The CoronaVac part of the study examined a group of 8.6
million people, the Pfizer BioNTech part studied 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)
Astrazeneca (AZN)