As a third wave of the pandemic begins to take hold across Indonesia, there are questions over its use of China’s Sinovac, after a series of studies suggesting the most commonly used COVID-19 vaccine in the Southeast Asian nation is no match for the Omicron variant of coronavirus.
On Friday, the country recorded 32,211 new confirmed cases of COVID-19, the highest official number since the Delta wave began to fade in mid-August.
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The positivity rate for individuals tested reached 10.29 percent on the same day, pushing Indonesia well beyond the 5 percent threshold the WHO uses to identify countries that have lost control of the virus.
Only 45.9 percent of Indonesia’s target population of 208 million people has been fully vaccinated compared with the global average of 53.4 percent, according to Our World in Data, and 79 percent of those are with Sinovac, according to Indonesia’s Ministry of Health.
The pace of inoculation has slowed further since the start of the year as many districts and provinces are refusing to use vaccines other than Sinovac due to complaints about the adverse effects of the Western-developed vaccines, raising concern that the Omicron wave could become a repeat of the Delta-driven second wave, which saw the hospital system collapse.
Studies raise doubts
In December, researchers at the University of Hong Kong and the Chinese University of Hong Kong published a study that found two doses of Sinovac did not produce sufficient antibodies to fight Omicron.
The study also revealed that Omicron significantly reduced the effectiveness of two shots of the Pfizer BioNTech vaccine, which is built on new Messenger RNA (mRNA) technology, which uses the genetic code of the coronavirus to trick the body into making viral proteins so the immune system starts to produce a defensive response. But the study stressed that a Pfizer booster was likely to be more effective than a third dose of Sinovac.
Another study conducted by the National Natural Science Foundation of China and published in the journal Emerging Microbes & Infections in the same month showed a “significant reduction” in the efficacy of a booster with Sinopharm, which, like Sinovac, is an inactivated vaccine that uses dead viral particles to expose the body’s immune system to COVID-19. “Overall, our study demonstrates that Omicron might more likely escape vaccine-induced immune protection compared to prototypes and other variants of concern,” the authors concluded.
And a study by Yale University and the Dominican Republic Ministry of Health published last month in the journal Nature Medicine showed no neutralising antibodies among those who received two shots of Sinovac.
“Our findings have immediate implications for multiple countries that previously used a two-dose regimen of CoronaVac,” the authors noted, using Sinovac’s other name.
China’s return to lockdowns as it faces the highest number of infections since the start of the pandemic and its rush to develop mRNA vaccines is further exacerbating concerns about the efficacy of the vaccines in developing nations such as Indonesia that rely on Chinese vaccines and cannot afford lockdowns. Then there is Singapore’s announcement in January that people who opted for inactivated Chinese vaccines will need to receive an mRNA shot as a booster to be considered fully vaccinated.
High cases, low admissions
An epidemiologist who predicted Indonesia’s deadly second wave in a report published by Al Jazeera a month before the peak, Dr Dicky Budiman believes the country will see 300,000 to 500,000 cases a day by the end of this month.
“Daily cases will be 10 times worse than the second wave but in terms of hospitalisations, it will only be half as bad,” Budiman said. “The death rate may also be lower but I cannot guarantee that because Sinovac is less effective against Omicron compared to messenger RNA vaccines.”
On a positive note, the high number of infections spread during the second wave will lend Indonesians a measure of immunity, he adds.
“I disagree with the term ‘super immunity’ because it can be misleading. The latest research shows an Omicron victim can be reinfected with the BA2 Omicron strain,” Budiman explained. “But the benefit of the Delta spread in July is that many Indonesians who have received Sinovac and became infected without knowing because they were asymptomatic will have some level of immunity. But it will only be temporary and the benefit will depend on where they live because the ramification of Omicron is that it relies on the landscape of immunity. Vaccination coverage in Indonesia has focused on Java and Bali, so problems will surface in other islands, as well as sub-districts in Bali and Java with low vaccination rates.”
To mitigate hospital admissions, Budiman says, the government should step up testing.
It should also reduce the time for booster shots for the elderly from six to four months after the second dose, while the booster for those who received two doses of Sinovac should be mRNA, he said. Yale’s study in the Dominican Republic found antibody levels against Omicron rose among those who received a Pfizer booster.
Western countries have stepped up booster programmes to combat the Omicron wave, and Indonesia began rolling out its booster programme last month but has so far inoculated only 1.9 percent of the target population.
Three new studies from the US Centers for Disease Control and Prevention in January also found that the Pfizer shot was effective in keeping most people who got Omicron out of hospital.
Dr Nadia Wiweko, the Ministry of Health spokesperson for COVID-19 vaccinations, says Indonesia plans to give boosters of the AstraZeneca or Pfizer vaccines to those double-jabbed with Sinovac.
Wiweko did not comment on Sinovac’s efficacy against Omicron or if the waiting period between the second and third jab should be reduced.
Dr Amin Soebandrio, a director of the Eijkman Institute, a government organisation studying tropical and emerging infectious diseases, downplays concerns about a deadly third wave. He cites new research by the Ministry of Health that builds on Budiman’s argument that Indonesians already carry some immunity because of mass infection during the Delta outbreak in July.
“It found 70 per cent of test subjects that has no history of reporting symptoms of COVID-19 and who have been vaccinated already have a level of antibodies, and that in populations with a history of the disease and who have been vaccinated, more than 90 percent have detectable antibodies,” Soebandrio said of the study, which is being prepared for peer-reviewed publication.
“Based on this data, I do not think Indonesians will be at a disadvantage for being vaccinated with Sinovac versus a messenger-RNA vaccine, as the level of antibodies is already high,” he said.
“Omicron is already the dominant variant reported in Indonesia, accounting for more than 90 percent of cases reported, and most of those infected are experiencing only mild symptoms or are asymptomatic. The number of those who need hospitalisation will not be as high as the second wave.”
Dr Leong Hoe Nam, an infectious disease specialist at the Rophi Clinic in Singapore, agrees, in part, although for different reasons.
“The short answer is Indonesians are disadvantaged by using Chinese vaccines that are a less effective substitute compared to messenger-RNA vaccines,” he said.
“But lady luck has dealt them a great stroke of fortune in that Omicron has turned out, anecdotally, to be much milder, even for those vaccinated with inactivated vaccines.”