Singapore NCID director: ‘Hardly any data’ on Sinovac’s potency against Covid-19 variants, unlike mRNA vaccines which are proven effective

A medical worker takes a box of Sinovac’s vaccine against the coronavirus disease from a refrigerator at a community health centre in Qingdao, Shandong province, China January 5, 2021. — China Daily pic via Reuters
A medical worker takes a box of Sinovac’s vaccine against the coronavirus disease from a refrigerator at a community health centre in Qingdao, Shandong province, China January 5, 2021. — China Daily pic via Reuters

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SINGAPORE, June 7 — Covid-19 vaccines using messenger ribonucleic acid (mRNA) technology, such as those made by Pfizer-BioNTech and Moderna, are the most effective against the coronavirus, including its variants, while there is hardly any data on how the Sinovac vaccine performs against the variants. 

This was a point made by Dr David Lye, the director of infectious disease research at the National Centre for Infectious Diseases (NCID), in a Facebook post on Monday (June 7). 

He wrote the post in response to recent calls by some local doctors for parents not to vaccinate their teenagers and urging the Government stop administering mRNA vaccines and use Sinovac instead. 

He said: “These doctors are pressuring the Health Sciences Authority to ignore rigorous review processes.” 

He noted that these messages, which went viral in recent weeks, were from a group of doctors including a Dr Paul IW Yang and a Dr Oon Chong Jin, a private cancer specialist who championed hepatitis B vaccination in Singapore.

“Incidentally, the current highly effective hepatitis B vaccine is not a killed whole virus vaccine,” he pointed out. The Covid-19 vaccine produced by Sinovac uses this traditional vaccine technology, which taps an inactivated coronavirus to trigger an immune response.

mRNA vaccines ‘among the most effective’

In his post, Dr Lye noted that mRNA vaccines are among the most effective Covid-19 vaccines available today.

They reduce symptomatic Covid-19 by 95 per cent, reduce hospitalisation for severe Covid-19 by more than 90 per cent and prevent transmission by more than 60 per cent, he said.

“There is a wealth of data from the United States, United Kingdom and Israel on their safety,” he wrote. 

“Importantly, mRNA vaccines are effective against the UK B117 (93 per cent), South African B1351 (75 to 90 per cent) and B1617.2 (88 per cent) variants. There is hardly any data on Sinovac against the variants.” 

Dr Lye added that laboratory studies showed that Sinovac may not work well against the B1128 variant which originated in Brazil or the South African B1351. 

“Although these doctors claimed Sinovac is superior to mRNA vaccines against variants, there is little data to confirm it is effective for B1617.2, and there is data to suggest it is less effective against other variants,” he said.

‘Potentially misleading’

Dr Lye warned that the messages circulated by the doctors via messaging platforms include “dubious international experts and research” and were “potentially misleading the public”. 

Last week, a petition was started online by a group of doctors urging the Government to include Sinovac in the national vaccine programme.

Some doctors among this group also wrote an open letter to parents asking them to think through carefully before choosing to inoculate their children against Covid-19.

A separate message by Dr Oon said that mRNA vaccines are ineffective against the B1617 variant that was first detected in India. 

Dr Lye said he suffered insomnia reading these messages and petitions. 

“Doctors are well respected in our society. Hence their advice may influence the public to avoid Covid vaccination. We should be upset when these doctors quote dubious international experts and research potentially misleading the public,” he said. 

Dr Lye said children and teenagers need to be vaccinated, even though they do not have severe symptoms from Covid-19, as they carry as much of the virus as adults do if they are infected and can infect older adults or those with poor immunity. 

He said that research in the United Kingdom has shown that the Pfizer-BioNTech and AstraZeneca vaccines have reduced household transmission by between 50 and 60 per cent. 

He also addressed the claim made by the doctors that mRNA vaccines were developed in a rush. 

“All Covid vaccines have been developed rapidly. There is huge investment by governments and companies. Many people volunteered in clinical trials. The trials could be completed rapidly as many countries experienced huge epidemics last year. In fact, Sinovac and Sinopharm were approved in China before the trials were completed.” he said. 

He added that there is no other reason why Singapore is not approving Sinovac except that more data is required from the manufacturer of the vaccine. 

“With the latest update on criteria for mRNA vaccines, there are very few reasons why a person cannot take mRNA vaccines. These doctors are pressuring the HSA (Health Sciences Authority) to ignore the rigorous review process,” he said. 

Dr Lye also said that even though the technology behind Sinovac is an old technology, it does not mean it is harmless and there is still a need to watch out for side effects. 

Two such vaccines for measles and respiratory syncytial virus led to more severe disease in the 1960s, and were withdrawn, he pointed out. 

“These doctors quoted a study that showed Sars-CoV-2 RNA from Covid infection could be integrated into human cells. While this has been quickly debunked by scientists as an artefact of the laboratory methods, these doctors failed to understand that mRNA from vaccines do not last for more than two days in our body and are different from viral RNA from Covid infection,” said Dr Lye. 

Ivermectin, fluvoxamine not proven to be effective

He also said that the use of ivermectin, which is a treatment for parasites, and fluvoxamine, which is an antidepressant, have not been proven to be effective in treating Covid-19. One of the messages circulated by the doctors had advocated the use of these drugs to treat the disease.

“Very few properly conducted clinical trials have been published. Among others, evidence cited for ivermectin in Covid included the faked database company called Surgisphere which led to two journal retractions from the prestigious New England Journal of Medicine and Lancet in 2020,” he said. 

A large trial on ivermectin conducted at a dormitory by National University Hospital doctors including Dr Paul Tambyah was not effective in preventing Covid-19, he added. 

“I urge the Singapore public to be aware and alert of fake science on social media. Anti-vaccine groups from Singapore and overseas are highly active. We must win this war against the virus. Effective Covid vaccines are a part of our solution.” — TODAY

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