A senior infectious diseases specialist, Associate Professor David Lye, has spoken up against misinformation being spread about Covid-19 vaccines by doctors, among others.

In a Facebook post yesterday titled "Why fake science and anti-vaccine groups are dangerous in a pandemic", the clinician-researcher at the National Centre for Infectious Diseases (NCID) said he needs to correct certain messages and petitions making the rounds that have caused him sleepless nights.

Some of these were from a group of doctors, including a Dr Paul I.W. Yang, and a Dr Oon Chong Jin, a private cancer specialist, he said.

"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 in his post.

Among other things, Prof Lye was referring to:

• An open letter last month that was written by 12 doctors and later retracted by 11 of them, urging the Government to give children the China-made vaccine, Sinovac, as it uses the traditional killed-vaccine technology "proven to be safe", and not mRNA vaccines Pfizer-BioNTech and Moderna.

They claimed that it was not known what side effects from the mRNA vaccines might surface 10 to 20 years down the road.

The petition was signed by Dr Benny K.H. Tan, Dr Chia A.M., Dr Clement Lai, Dr Colleen Thomas, Dr C.T. Tan, Dr Diane Jek, Dr Judy Chen, Dr Kee Leng Chee, Dr Kho Kwang Po, Dr Paul I.W. Yang, Dr Suzie Lee and Dr Khoo Boon Lian. All except Dr Khoo retracted it.

Currently, Singapore's public vaccination programme uses only the Pfizer and Moderna vaccines. Sinovac, which has been approved by the World Health Organisation under its emergency use listing, will be available here only at some private clinics, under a Special Access Route.

• Comments from Dr Oon - who had been involved in testing the hepatitis B vaccine here more than 30 years ago and claimed that the Pfizer vaccine "is useless now and obsolete in the presence of mutations". He had promoted the use of Sinovac for everyone, including children, saying it could protect against the B1617 variants that had ravaged India. He claimed that the Pfizer and Moderna mRNA vaccines could not do this.

• An online petition by Citizens Against Covid-19 last Saturday that said those under 20 years old should not be vaccinated as "the mortality rate for this age group is statistically zero".

The petition also calls for a nationwide Outpatient Home Treatment Plan - where general practitioners provide the cheap antiviral drug ivermectin as treatment and prevention. It said the drug "destroys all coronaviruses, including its mutants".

Prof Lye said all those claims are wrong.

On vaccinating the young, he noted that while they do not usually have severe Covid-19 infections unless they have health problems, they carry as much of the virus as adults do if infected, and can infect older people and those with poor immunity.

He pointed out that while some claims said that mRNA vaccines do not reduce transmission, a study in Britain showed that the Pfizer shot and the vaccine by AstraZeneca reduced household transmission by 50 per cent to 60 per cent.

The mRNA vaccines are among the most effective vaccines for Covid-19, Prof Lye said. They reduce symptomatic Covid-19 by 95 per cent, reduce hospitalisation for the severe form of the disease by more than 90 per cent, and prevent transmission by more than 60 per cent.

There is a wealth of data from the United States, Britain and Israel on their safety, he said, and importantly, mRNA vaccines are effective against the B117 (93 per cent), B1351 (75 per cent to 90 per cent) and B16172 (88 per cent) variants.

"There is hardly any data on Sinovac against the variants. Laboratory studies showed that Sinovac may not work well in (the) B1128 and... B1351 variants," he said.

"Although these doctors claimed Sinovac is superior to mRNA vaccines against variants, there is little data to confirm it is effective for B16172, and there is data to suggest it is less effective against other variants."

He said "there is no reason for Singapore not to approve Sinovac. But approval requires data judged to be adequate".

The Health Sciences Authority (HSA) is still awaiting a reply from Sinovac on its queries, he pointed out. "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 HSA to ignore rigorous review process."

He also debunked the contention that Sinovac is safe because it uses traditional methods. "Even though inactivated whole virus vaccine is an old technology, it is not harmless and we still need to watch out for side effects. In the 1960s, two inactivated vaccines for measles and respiratory syncytial virus led to more severe disease, and were withdrawn."

Noting how the doctors quoted a study that showed how RNA from the Covid-19-causing virus could be integrated into human cells, he said: "While this has been quickly debunked by scientists as an artefact of the laboratory methods, these doctors failed to understand that mRNA from vaccines does not last for more than two days in our body and is different from viral RNA from Covid infection."

He also criticised calls by some doctors to use ivermectin, which is used to treat parasites, and fluvoxamine, an anti-depressant, instead of vaccination.

Ivermectin has not been proven to be effective against Covid-19, he said.

"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.

In fact, a local study at a dormitory, led by Professor Paul Tambyah, a senior infectious diseases consultant at National University Hospital, found ivermectin to be not effective in preventing Covid-19.

"I urge the Singapore public to be aware of and alert to fake science on social media," said Prof Lye, who made headlines last month when he asked people to form and stick to their own social bubbles to keep their families safe.

"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."

Dr Benjamin Seet, a deputy chief executive at National Healthcare Group who chaired the panel that picked the vaccines for Singapore, in a LinkedIn post applauded Prof Lye's comments.

He said: "Doctors are taught that when they are unable to do good, they should do no harm. It is sad that in this age where reliable information is so readily accessible, that some choose to become purveyors of mistruths, poor science and misguided advice.

"I'm glad that David, my colleague at NCID, has stood up against this. We should draw a line when this has obviously been crossed."

Dr Yang, a general practitioner who had drafted the open letter signed by a dozen doctors, would only say that Prof Lye "should trust your elders", referring to Dr Oon, who could not be reached.

Ms Cheryl Lee, 62, a social entrepreneur and the main author of the online petition by Citizens Against Covid-19, said her group was a grassroots movement with a mission to educate the public on vaccine safety.

"As far as possible, we authenticate the news and research studies, and disregard fake news. We believed that one should hear diverse views in order to obtain a holistic perspective of a difficult situation so that we can make better informed choices."

When it came to children, Ms Lee said that according to the World Health Organisation, there was not enough evidence on the use of vaccines against Covid-19 in children for them to be vaccinated.

Over the weekend, several political leaders reiterated the need to make decisions based on science.

Senior Minister Teo Chee Hean, who is also the Coordinating Minister for National Security, posted on Facebook last Saturday after a chat with Members of Parliament and volunteers on "all the noise suddenly being created" on social media.

He said: "We concluded that we should focus on the science and take the advice of our medical experts, and decide what is the appropriate action based on our public health needs in Singapore."

On Monday, Speaker of Parliament Tan Chuan-Jin also posted on Facebook: "In the midst of a major health crisis, there are those who are seeking to mislead and misinform for political reasons because it helps to erode trust and confidence."