BEIJING, June 29 (Reuters) - Many countries from China to
Indonesia and Brazil rely heavily on Chinese vaccines to
inoculate their people against COVID-19, but there are growing
concerns about whether they provide enough protection against
the Delta variant, first identified in India.
Below are views from China's health experts about the
effectiveness of home-grown vaccines against the Delta, which is
becoming the globally dominant variant, and virus preventive
measures China is taking.
DO CHINESE VACCINES WORK AGAINST DELTA?
China has not provided vaccine effectiveness results against
the variant based on large-scale data in clinical trials or
real-world use, nor offered detailed information from lab tests,
but Chinese experts are urging people to get inoculated as soon
The lack of detailed data on the Chinese vaccines against
the Delta has hobbled any meaningful peer reviews by foreign
Researchers found that Chinese vaccines are somewhat
effective in reducing the risk of symptomatic and severe cases
caused by Delta, Zhong Nanshan, a epidemiologist who helped
shape China's COVID-19 response, told reporters.
It is based on analysis of infections in Guangzhou city, and
Zhong told Reuters the results are preliminary and the sample
size is small.
Sinovac spokesman Liu Peicheng told Reuters preliminary
results based on blood samples from those vaccinated with its
shot showed a three-fold reduction in neutralizing effect
against the Delta.
He said a booster shot following the two dose-based regimen
could quickly elicit stronger and more durable antibody reaction
against the Delta. However, he didn't provide detailed data.
Antibodies triggered by two Chinese vaccines are less
effective against the Delta compared with other variants, Feng
Zijian, former deputy director at the Chinese Center for Disease
Control and Prevention, told state media last week.
Feng did not provide details including the name of the two
The shots could still offer protection, since none of those
vaccinated in southern Guangdong province, where China's first
cases of the Delta variant were found, developed severe
symptoms. All severe cases are from unvaccinated people.
Jin Dong-Yan, a virologist at the University of Hong Kong,
said Feng's comment alone is not enough to back up the claim
that Chinese vaccines are effective against severe cases, as
more data is needed.
Indonesia, which has reported record daily cases recently
due to a surge in the Delta variant, saw hundreds of medical
workers infected by the COVID-19 despite being vaccinated with
Sinovac's shot, officials said earlier this month.
It was not immediately clear, however, if the Indonesian
medical workers were infected by the Delta variant.
HOW DO THEY COMPARE WITH WESTERN SHOTS?
A study by Public Health England (PHE) found in May the
Pfizer-BioNTech vaccine was 88% effective
against symptomatic disease from the Delta two weeks after the
That compared with 93% effectiveness against the Alpha
variant, first identified in Britain.
Two doses of the AstraZeneca vaccine were 60%
effective against symptomatic disease from the Delta compared
with 66% effectiveness against the Alpha, PHE said.
There is no substantial data showing how protective Johnson
& Johnson's single-dose COVID-19 vaccine is, and U.S.
infectious disease experts are weighing the need for booster
shots using mRNA vaccines.
HOW SEVERE WAS THE GUANGDONG OUTBREAK?
Guangdong, China's major manufacturing and export hub,
became the country's biggest cluster of Delta cases since
reporting its first locally transmitted Delta variant infection
The Delta infections included 146 cases in Guangdong's
capital Guangzhou and several cases from the southern tech hub
of Shenzhen and nearby Dongguan city.
No new domestic transmissions of any variant have been
reported in the province from June 22.
WHAT CHINA HAS DONE?
Guangdong, which has 126 million people, has fast-tracked
its vaccination effort since the outbreak. It had administered
just 39.15 million doses as of May 19, but the number shot up to
101.12 million by June 20.
Guangzhou, Shenzhen and Dongguan quickly sealed off
neighbourhoods where those who were infected and their contacts
visited and launched multiple rounds of mass testing, following
the protocols observed during previous outbreaks.
The cities also required those travelling out of the
province to show proof of negative COVID-19 test results.
Zhong, the epidemiologist, said that without effective
control measures 7.3 million people in Guangzhou city would have
been infected in the first 20 to 30 days after the initial case.
(Reporting by Roxanne Liu and Ryan Woo; Editing by Miyoung Kim
& Shri Navaratnam)