Sinovac Vaccine Falls Short of Expectations, But Options Limited

KOMPAS.com - "Better than nothing."

That's one infectious disease expert's assessment of Sinovac Biotech's COVID-19 vaccine, following reports that hundreds of Indonesian health care workers who had received the vaccine caught the disease anyway.

At least 10 doctors have died despite having been fully vaccinated with two doses of Sinovac's CoronaVac vaccine, according to the Indonesian Medical Association.

It's unclear how widespread these "breakthrough" infections are. It's also not clear how severe most of the infections are. Little peer-reviewed data on the vaccine are available.

What information is available suggests that the vaccine is less potent than others, especially against the highly contagious delta variant that was first detected in India.

Also read: Indonesian Medical Association: Covid-19 Killed Over 700 Medical Personnel

However, access to more effective vaccines is limited in much of the world, experts note. Indonesia is one of dozens of countries where the Chinese company's vaccine makes up a substantial part of the available doses.

While the shortage of published peer-reviewed data makes it hard to evaluate the vaccine, a few available studies provide a glimpse.

The government of Uruguay released data earlier this month showing CoronaVac reduced COVID-19 infections by 61%, hospitalizations by 92% and deaths by 95%.

Although not peer-reviewed, the study is one of a few that compare CoronaVac with another vaccine.

FILE - Empty vials to be filled with the Pfizer/BioNTech vaccine are seen at a production facility in Reinbek, near Hamburg, Germany, April 30, 2021.

Pfizer-BioNTech

The Pfizer-BioNTech shot performed better against infections in general in the study, lowering rates by 78%. But hospitalizations and deaths were about the same.

It's not clear what the dominant variant was during the study, however.

A key measure of vaccine potency is the level of neutralizing antibodies — the proteins the immune system produces that prevent the virus from infecting cells.

The Pfizer and Moderna vaccines produce very high levels of these antibodies, which help maintain protection against variants, said Peter Hotez, dean of the National School of Tropical Medicine and a professor at the Baylor College of Medicine.