Explainer: How effective and safe is the Pfizer-BioNTech vaccine S'pore is rolling out?

• Of the more than 200 vaccine candidates being developed, Singapore chose the Pfizer-BioNTech vaccine to be the first to be used here
• Pfizer-BioNTech have reported no serious safety concerns from their vaccine based on clinical trials
• The authorities in the UK said there had been two reports of anaphylaxis and one report of a possible allergic reaction to the vaccine
• There is also no conclusive evidence that the vaccine is effective on children

SINGAPORE — Prime Minister Lee Hsien Loong in his national address on Monday (Dec 14) said that the authorities have approved the Pfizer-BioNTech Covid-19 vaccine for use here.

Mr Lee said that the first shipment should arrive by the end of December and that Singapore is among the first countries to receive it. He added that there will be enough vaccines for everyone here by the third quarter of next year.

Here is what you need to know about it.

HOW EFFECTIVE IS THIS VACCINE?

Of the more than 200 vaccine candidates that are being developed, Singapore chose the Pfizer-BioNTech vaccine to be the first to be used here, though Mr Lee said that other vaccines would arrive in the months ahead.

The vaccine was developed by American pharmaceutical giant Pfizer and its smaller partner, German company BioNTech, in less than a year since the coronavirus first emerged — a short time in the field of vaccine development.

Two doses of the vaccine are required, to be taken 21 days apart. It must be kept at very cold temperatures — about negative 70°C.

The firms announced preliminary results in November that suggested the vaccine was more than 90 per cent effective — a very high figure among vaccines. About 44,000 people have taken part in the clinical trials.

Pfizer then published the final results from the trials on its website, showing that the vaccine had a 95 per cent level of efficacy in preventing Covid-19, 28 days after the first dosage is given. This means that a week after a person gets the second dose, if the person has not been infected by the coronavirus before, there is a 95 per cent chance that the vaccine will work.

The US Food and Drug Administration had set a bar of 50 per cent efficacy for vaccine makers wishing to seek emergency authorisation, while most experts had hoped for 70 per cent efficacy or higher. The Pfizer-BioNTech results easily top those benchmarks.

IS IT SAFE, ESPECIALLY FOR THE VERY YOUNG AND OLD?

The New York Times reported that Pfizer and BioNTech have documented no serious safety concerns from their vaccine based on clinical trials.

However, the healthcare authorities in the United Kingdom said that there had been two reports of anaphylaxis and one report of a possible allergic reaction since the rollout of the Pfizer-BioNTech vaccine began. Anaphylaxis is a severe or even life-threatening allergic reaction to a medicine or food.

The developers have since advised that any person with a history of anaphylactic reaction to a vaccine, medicine or food should not receive the vaccine.

Asked by TODAY on whether the authorities here have similar concerns, Associate Professor Kenneth Mak, director of medical services at the Ministry of Health (MOH), said that while there are concerns about allergic reactions, this is a similar concern for any other vaccine.

“Any medication that is given to patients can give rise to allergic reactions… the Health Sciences Authority (HSA) and the Expert Committee (on Covid-19 Vaccinations') recommendation to us is to not vaccinate individuals who have a history of severe allergic reactions or anaphylactic reactions.”

Assoc Prof Mak, who was speaking at a press conference by the national Covid-19 task force after PM Lee's televised address, said that all individuals receiving the vaccination must be observed for a short period of time to ensure they do not have signs to suggest that an allergic reaction is occurring. If a person shows an allergic reaction after the first dose of the vaccine, the second dose should not be given, he added.

The vaccine appears to be effective for seniors. HSA said that the vaccination demonstrated its 95 per cent efficacy consistently across different age groups 16 years and older in the clinical trial participants, whose ages ranged from 16 to 91 years.

Asked by the media whether seniors with chronic diseases are safe to be vaccinated, Assoc Prof Mak said that this demographic will be prioritised for vaccination, especially if they have conditions that affect their ability to combat and recover from Covid-19.

“The engagement with doctors is continuing at this point in time, and we will be providing information concerning the vaccine… so they can also provide information to their patients, to allow their patients to make an informed decision.”

The vaccine’s efficacy on children is also not known. The Pfizer-BioNTech trials were initially open to people aged 18 or older, but in September, it began including teenagers as young as 16. Last month, they launched a new trial on children as young as 12 years old and plan to work their way to younger ages.

HSA said that pregnant women, immuno-compromised persons and those under the age of 16 should also not receive the Pfizer-BioNTech vaccine because the safety and efficacy data on these groups of persons are not available yet.

WHO WILL GET IT FIRST?

PM Lee said that the Government has accepted the proposals by the MOH Expert Committee on Covid-19 Vaccinations, which recommend that the entire adult population should be vaccinated, but that it be made voluntary. The vaccinations will be free.

Priority will be given to those who are at greatest risk such as healthcare workers and frontline personnel, as well as seniors and the vulnerable.

Then, the rest of the population will be progressively vaccinated so that anyone who wants a vaccination can get it by the end of next year.

WILL OTHER VACCINES BE AVAILABLE HERE?

PM Lee said in his speech that the authorities had signed advance purchase agreements and made early down-payments for the most promising vaccine candidates, including with another American firm, Moderna, and China’s Sinovac.

He added that residents here can expect other vaccines to arrive in Singapore in the coming months.

WHICH OTHER COUNTRIES ARE GIVING VACCINES?

The UK was the first to start vaccinating its citizens and has since last Tuesday been offering the Pfizer-BioNTech jab to frontline healthcare workers and elders. It is prioritising it for all people above the age of 50, and younger adults with underlying health conditions, before the rest of the population gets the jab.

In the US, the first shipments of the Pfizer-BioNTech began to roll out on Sunday. Healthcare workers and older residents of long-term care homes will be first in line.

More than 100 million people, or about 30 per cent of the US population, could be immunised by the end of March, the authorities there said on Sunday.

A vaccine developed by China’s SinoPharm has an 86 per cert efficacy rate, based on the outcomes of trials, and in November, British daily The Guardian reported that almost a million people in China had taken the vaccine in its testing phase.

Indonesia, which is facing a mounting Covid-19 death toll, received 1.3 million doses of a Covid-19 vaccine made by China’s Sinovac, with another 1.8 million set to arrive next month.

However, Sinovac said that it is not yet able to determine the efficacy of the vaccine, which was at odds with a statement by its Indonesian partner Bio Farma that said interim data showed 97 per cent efficacy. Sinovac clarified that the vaccine had created antibodies in 97 per cent of those who received it, Bloomberg reported.