SINGAPORE – As Southeast Asia grapples with a record-breaking surge in Covid-19 infections and deaths, regional nations are turning away from Chinese-made vaccines in favor of Western-made shots amid growing evidence the former are less effective against the highly contagious Delta variant.

Beijing’s leading vaccine developers, private biopharmaceutical firm Sinovac Biotech and state-owned Sinopharm, have shipped hundreds of millions of doses worldwide and are key to the World Health Organization’s COVAX scheme aimed at distributing shots to poorer countries.

China’s indigenously developed vaccines, studies show, offer a measure of protection and are still considered to be highly effective against severe disease and hospitalization. They also are more easily stored and transported than certain Western-made jabs, making them comparatively cost-effective.  

But it is increasingly less clear how well Chinese shots protect against more transmissible Covid-19 variants, not least the fast-spreading Delta strain that is now causing runaway caseloads and pushing regional health systems to the brink of collapse. Emerging data shows diminishing efficacy levels against variants in several major Covid-19 vaccines.

Southeast Asia is especially exposed to Sinovac’s efficacy, which has varied widely in different studies. The Philippines and Indonesia have relied on Sinovac for the bulk of their vaccines, while Malaysia has opted for a diversified mix of mainly Sinovac, Pfizer-BioNTech and AstraZeneca. Thailand had also looked largely to Sinovac for its beleaguered vaccine rollout.  

As Western countries largely prioritized immunizing their own populations, China filled the gap by positioning itself at the center of global vaccine cooperation, selling and donating its jabs in a bid to win wider international influence and counter narratives about its role as the origin of the pandemic.

But rising reports of hundreds of breakthrough infections and a lesser number of deaths among medical and front-line workers in Indonesia and Thailand who were fully vaccinated with Sinovac have undermined confidence in the shot, marking a blow to Beijing’s “vaccine diplomacy” in the region.

Singapore, one of the few regional countries to have consistently brought its outbreaks under control, announced this month that people who opted for Sinovac shots would be excluded from the island-state’s count of total vaccinations. They will be required to undergo testing at public events that those inoculated with other vaccines are exempted.  

Two men wait outside a clinic after receiving the Sinovac vaccine on June 24, 2021 in Singapore. Photo: AFP via NurPhoto / Suhaimi Abdullah

When asked whether Sinovac would be included in the national vaccine program, which relies on Pfizer-BioNTech and Moderna, Health Minister Ong Ye Kung told a media briefing on July 8 that “we don’t really have a medical or scientific basis or have the data now to establish how effective Sinovac is in terms of infection and severe illnesses on Delta.”

Malaysia, now grappling with one of Southeast Asia’s highest per-capita infection rates, announced on July 15 that it would phase out and altogether stop administering Sinovac after its 12 million vial supply is fully distributed later this month. Authorities will instead offer the Pfizer-BioNTech vaccine after securing around 45 million doses, enough to cover 70% of its population.

Malaysian health officials have denied that efficacy issues contributed to the decision to discontinue Sinovac’s use and say they have a sufficient number of other vaccines for its national program. Doses of the Chinese-made jab will reportedly be made available on the private market beginning in August for those who wish to take them.  

The Philippines said last month it planned to import 40 million doses of the Pfizer-BioNTech vaccine, its largest vaccine purchase agreement yet. Its first doses of Moderna, which it ordered in bulk in March, began arriving late last month. The country previously relied primarily on Sinovac’s shot and launched its vaccination campaign in March after receiving jabs donated by Beijing.   

“We can expect the Sinovac vaccine could face stiffer competition in the coming months from shots that have demonstrated effectiveness against the Delta variant, just as we can expect Sinovac to be improved upon to deal with new variants,” said Eugene Tan, a law professor at the Singapore Management University (SMU).

“China may well be redoubling their efforts to improve on Sinovac and Sinopharm in terms of their effectiveness. It is a matter of national pride, particularly for the Chinese, that their vaccines are perceived to be as good as any other,” he added.

Six months since Indonesian President Joko Widodo rolled up his sleeve to receive his first shot of the Sinovac vaccine to kick off the nation’s mass inoculation campaign, the world’s fourth-most populous nation has emerged as Asia’s latest new Covid-19 epicenter with nearly 2.9 million total cases and over 73,500 deaths.

Complicated geography, supply snags and vaccine hesitancy have crimped Jakarta’s immunization efforts, with just 5.8% of its 270 million people fully vaccinated, a factor fueling a devastating vertical surge of new infections recently described by Luhut Pandjaitan, a Cabinet minister, as the “worst-case scenario.”     

At least 90% of Indonesia’s roughly 160,000 doctors have been vaccinated with Sinovac, according to the Indonesian Medical Association, which said in late June that at least 20 fully vaccinated doctors had died from Covid-19 over a five-month period, though it is unclear whether underlying illnesses or other healthcare factors contributed to the deaths.

A health worker prepares the Covid-19 Sinovac vaccine at Aceh Hospital in Indonesia on January 15, 2021. Photo: Khalis Surry / Anadolu Agency

The archipelagic nation has reported more new Covid-19 cases than any country worldwide in recent days, with a record number of fatalities being reported among doctors. According to Indonesia’s Doctors Association, a total of 114 doctors died from Covid-19 between July 1 to 17, the highest number for any period of similar length since the beginning of the pandemic.

Thailand, now in the throes of its worst outbreak, began inoculating medical workers with Sinovac in February, but since June has phased in locally-manufactured AstraZeneca vaccines. The kingdom’s health ministry says 618 out of 677,348 frontline personnel who received two Sinovac doses were infected between April and July. At least one fully vaccinated nurse reportedly died.  

Both countries plan to offer booster shots manufactured by Western drugmakers to medical workers already immunized with the Chinese-made vaccine. Jakarta plans to give its 1.47 million health workers an extra jab of Moderna, while Bangkok says it plans to inoculate its 700,000 medical workers with donated Pfizer-BioNTech shots.

On July 12, Thai authorities said that they would also allow those who took a dose of Sinovac to switch to AstraZeneca for the second shot in a bid to increase protection, an untested mix-and-match approach that several countries are examining to combat a global surge of variant-caused infections.

Southeast Asian countries are also grappling with how to best publicly acknowledge growing doubts about the effectiveness of Chinese-made vaccines, cognizant that overly critical messaging could earn Beijing’s rebuke.  

A leaked Thai Ministry of Public Health document stirred controversy by revealing official concerns that giving health workers a booster shot of Pfizer-BioNTech would send the wrong public message by “admitting that the Sinovac vaccine is not effective.”

Singaporean officials have been more forthright about their misgivings. Kenneth Mak, Singapore’s director of medical services, said at a June 18 press conference that there was a “significant risk of vaccine breakthrough” associated with Chinese jabs based on evidence from Indonesia and elsewhere.

“One shouldn’t be surprised if Beijing is of the view that Singapore has been too harsh and partial in its assessment of Sinovac in comparison with Pfizer-BioNTech and Moderna,” said academic Tan. “Beijing would rather that Sinovac be put on the same standing as the other vaccines on the national vaccination program.”

Tan added that while China “may well keep in mind Singapore’s stance on Sinovac,” the city-state’s approach to vaccine selection has been transparent and strictly scientific, and that vaccine preferences “ultimately would not bedevil bilateral relations as there are many fronts where both countries are cooperating.”

Health workers vaccinate an Indonesian woman with the Sinovac vaccine in Jomblang Village, Semarang, Central Java Province, Indonesia on July 18, 2021. Photo: AFP via NurPhoto / WF Sihardian

Health officials in Singapore have cited “outstanding data” on the Sinovac vaccine’s quality and safety profile that the manufacturer had – until recently – failed to provide as a reason for its exclusion from its national inoculation program. The Chinese drug maker reportedly submitted the requested data to the city-state’s Health Sciences Authority earlier this month.

Singapore’s vaccine regulator has said a complete evaluation of the data and its decision on the shot’s inclusion in the national program would be complete in four to six weeks. However, the majority of eligible recipients in the city-state would by then have already fully completed their two-dose immunization.

With over 40% of its population fully immunized and 69% having received at least one dose of a Covid-19 vaccine, Singapore is quickly catching up with developed world countries that have achieved high rates of vaccination. The city-state aims to have two-thirds of its 5.7 million population fully vaccinated by August 9, when it commemorates national independence.

Though Sinovac has yet to be approved by the city-state’s regulators, authorities have nonetheless allowed it to be used as a voluntary alternative for severely immunocompromised patients and those with a history of allergic reactions to messenger RNA (mRNA) vaccines like Pfizer-BioNTech or Moderna, which are based on a newer technology that uses the genetic code of a pathogen to trigger immunity.

Sinovac uses the more traditional method of exposing the body to an inactivated Covid-19 virus to prompt an immune response, a platform used in many other shots, such as the polio vaccine. According to data from the WHO, the shot is 51% effective at preventing symptomatic disease compared to a 95% efficacy rate for Pfizer-BioNTech and 94.1% for Moderna.

Singapore’s health ministry procured a stock of 200,000 Sinovac shots last year before clinical data about the vaccine’s efficacy was available. At least 31 private clinics have sold and distributed the jab. But those who take Sinovac are not eligible to receive financial assistance from the state if they develop serious side effects from the still unregulated shot.

Despite its exclusion and lower efficacy, private clinics in Singapore saw overwhelming demand for the Sinovac shot when it was made available last month. Some opted for the Chinese-made jab for medical reasons, while others including Chinese nationals in the city-state have reportedly done so for nationalistic or personal reasons.

“I am aware that the China government encourages PRC (People’s Republic of China) nationals to take the Sinovac vaccine,” said Huang Yan, a nurse from China’s Sichuan province working at Mount Elizabeth Hospital in Singapore who told Asia Times she opted to take Pfizer-BioNTech vaccine when it was offered to medical workers in December.

The Pfizer-BioNTech vaccine has proven more effective than China’s Sinovac. Photo: AFP

“As a frontline worker, I felt it necessary to take the first available vaccines in Singapore to protect myself and my family,” she said, adding that some staff members at her hospital chose to wait for the Sinovac vaccine, with some fearing possible side effects from mRNA shots.

Another reason for Sinovac’s apparent popularity in Singapore, said Tan, is that there would be fewer restrictions to enter China, if any, for travelers fully vaccinated with Sinovac. Chinese embassies began streamlining visa application procedures for foreigners inoculated with Chinese-made vaccines in March. China relies exclusively on its own domestically-produced jabs and has not approved foreign-made shots.

Beijing continues to maintain some of the world’s strictest pandemic control measures, and the lifting of border restrictions will thus ultimately hinge on the efficacy of Chinese vaccines, particularly against the Delta variant, a subject that observers say is an increasingly sensitive topic in China.

“Beijing has not said anything officially, but I suspect that they may bristle at questions about the efficacy of their vaccines,” said Ja-Ian Chong, a political scientist from Singapore. “If vaccines produced elsewhere prove to be more effective and preferred than China-developed vaccines, there is some risk of further politicization.”

Beijing’s health officials have said little about how well Chinese vaccines work against the Delta variant. Sinovac spokesman Liu Peicheng told Reuters in June that blood samples from vaccinated patients showed a three-fold reduction in neutralizing effect against the Delta strain and suggested a booster shot for better protection.

Feng Zijian, a senior official at the Chinese Center for Disease Control and Prevention, told Chinese state media in June that antibodies triggered by “two” Chinese-made Covid-19 vaccines, the names of which he did not specify, were less robust against the Delta variant compared with other strains, but that the shots still offered protection.

Clinical trials for Sinovac have produced a range of results, with a recent study published in the Lancet medical journal determining that two doses of the vaccine were 83.5% effective in protecting against symptomatic infections. But the study, conducted in Turkey between September 2020 and January 2021, did not take new variants into account.

A Thai medical staff member administers a dose of the Sinovac vaccine to a resident of the Klong Toey community, one of the areas with the highest number of Covid-19 infections in the Thai capital, outside an indoor football stadium in Bangkok on May 11, 2021. Photo: AFP / Lillian Suwanrumpha

A new preliminary study by researchers at Thailand’s Thammasat University determined that Sinovac’s protection rate as measured by antibody levels ranged between 60% and 70% for the first 60 days after the second vaccine dose, but the rate steadily declined over time and appeared to halve every 40 days.

According to a Hong Kong study also published in the Lancet, antibody levels among health workers who have been fully vaccinated with BioNTech’s mRNA shot were about 10 times higher than those observed in the recipients of the Sinovac vaccine, which researchers said could “translate into substantial differences in vaccine effectiveness.”

Leong Hoe Nam, an infectious diseases physician at Singapore’s Mount Elizabeth Hospital, said that with the rise of highly contagious variants, the effectiveness of mRNA vaccines by Pfizer-BioNTech and Moderna has also appeared to falter, alluding to recent data from Israel that also showed reduced effectiveness months after inoculation.

Israel’s health ministry said on July 7 that it detected a decrease in the effectiveness of the Pfizer-BioNTech shot in preventing both infection and symptomatic disease, with its protection rate falling to 64% in June in people who had been vaccinated in January or February, while still being 93% effective in preventing hospitalizations and serious illness.

US drugmaker Pfizer and its German partner BioNTech reportedly plan to ask US and European regulators to authorize a booster dose of its vaccine within weeks. Pfizer has said its own data from the United States had shown an erosion of the vaccine’s efficacy to the mid-80% range after six months.

Meanwhile, the organizers of a late-stage human trial of the Sinovac vaccine in Chile, which has relied heavily on Chinese-made jabs, determined the effectiveness of the shot reduced four-fold against the Delta variant as compared to the original coronavirus strain detected in China and recommended a third dose of the vaccine for enhanced protection.

“As the coronavirus continues to mutate, we have seen the efficacy of vaccines on a whole fall. We can expect even the two-dose regimen of the mRNA vaccines to falter and sink to new lows,” Leong told Asia Times. “A third booster dose for all vaccine types would be a potential solution to this problem moving forward.”