A decision on approving the Pfizer vaccine for use against Covid in Australia is imminent with the recommendations of the independent Advisory Committee on Vaccines now in the hands of the drugs regulator.
The chair of the committee, Prof Allen Cheng, said it had finished reviewing the vaccine data for the Therapeutic Goods Administration (TGA) after holding a meeting about the vaccine on Friday.
“We just give the TGA the advice, it’s really up to them now,” he said. “But I’m sure it’s going to be pretty soon.”
Guardian Australia spoke to Cheng about what the committee does, how it assessed the Pfizer vaccine and other vaccine candidates, and what the committee has learned so far from countries already rolling out vaccines.
What does the Advisory Committee on Vaccines actually do?
“The main question we are asked by the TGA is basically, does the vaccine do what it says on the package?” Cheng said. “Primarily we consider, is it effective for disease? If you are a person getting this vaccine, do the benefits outweigh the risks?”
There are other advisory groups considering questions like how to roll the vaccine out and the logistics of that, but Cheng’s committee is more concerned with the vaccine itself.
It also advises the TGA on appropriate clinical use of the vaccine. For example, the committee may recommend that some people shouldn’t be given the vaccine at all, or that some groups may be at higher risk of side effects than others and how to manage that.
“The other aspect we think about is quality,” Cheng said. “The TGA does a lot more work on that, and makes sure each drug has the same ingredients, that the ingredients are quality, and that there is the same amount of vaccine in each dose. But that crosses over a bit with what we do, because if the vaccine isn’t good quality, then it’s probably not safe and effective.”
The advisory committee has 10 members across areas such as nursing, consumer advocacy, rural and regional health, paediatrics, pharmacy, public health, microbiology, epidemiology and infectious diseases.
Cheng is the chair, and is uniquely positioned for the role as he is an epidemiologist, a biostatistician, a physician working in hospital infectious diseases wards, the president of the Australasian Society for Infectious Diseases, and chair of the Australian Technical Advisory Group on Immunisation. He was also acting chief health officer for Victoria during the state’s virus second wave.
“The committee is just one cog in the whole machine that considers the vaccine,” Cheng said. “Before the vaccine data even comes to us, the TGA has done all their background work, examining dossiers of information.”
What has been learned about the Pfizer vaccine from other countries’ experience?
The US and UK regulators have reported a number of cases of anaphylaxis, a severe and dangerous allergic reaction, associated with the vaccine.
“We now know this occurs in about one in every 100,000 doses,” Cheng said. “So it’s not super common. People who already have severe allergies and who need to carry an EpiPen are the ones affected, but it looks like it may be safe to give it to them as long as they’re in a supervised place that can handle severe allergies.”
While it is best practice to monitor anyone who receives a vaccine for 15 minutes in case of reaction, data had revealed some allergic reactions were occurring closer to half an hour after vaccination.
“So the advice can be, if you do choose to vaccinate and you have a history of severe allergy, then you might need to hang around for 30 minutes so you can be monitored,” Cheng said. “That’s the sort of thing that we learn from people that have gone before us. And that helps a lot, because now we can have a better discussion with people about risks, and how we’re going to manage those risks.”
There were also reports from Norway that the Pfizer vaccine had been associated with a small number of deaths in frail and elderly people in nursing homes. This data came in after the committee had handed its recommendations to government, but the TGA and other groups advising it discuss such data directly with their counterparts in Norway.
“It’s looking like it probably is just because people have a high mortality in nursing homes in general, and the deaths are not specific to this vaccine,” Cheng said.
What about pregnant women?
The US Centers for Disease Control and Prevention (CDC) issued a statement on 7 January saying there was limited data about the safety of Covid-19 vaccines for people who are pregnant and breastfeeding.
The CDC advice said: “Pregnant people with Covid-19 have an increased risk of severe illness, including illness that results in ICU admission, mechanical ventilation, and death compared with non-pregnant women of reproductive age.
“Additionally, pregnant people with Covid-19 might be at increased risk of adverse pregnancy outcomes, such as preterm birth, compared with pregnant women without Covid-19,” the advice states. Women should consider these facts to make a personal choice about whether to get vaccinated, the CDC recommends.
Cheng said context was important.
“There is a raging epidemic in the US and people are getting Covid left, right and centre, and that makes the risks and the benefits of getting vaccine a little bit different to what they would be in Australia where we virtually don’t have any Covid. But then, if you were a pregnant nurse who works in hotel quarantine, the equation might be a little bit different.
“Theoretically we don’t think that there’s any risk to the baby. And in fact, there might be some protection to the baby so the antibodies that you get that protect you actually also flow to the baby.”
What else can Australia learn from other countries?
Even once Australia rolls out the vaccine, we will be unable to determine the true effectiveness of the vaccine here, because there are not enough people with Covid to study it properly.
“In clinical trials we talk about the efficacy of a vaccine in terms of preventing disease, but in the real world it is never exactly like a trial where things are done in more controlled environments on more healthy people,” Cheng said.
“From other countries, the UK and the US and Israel, where the vaccine is already getting rolled out, we will learn how much of an impact this vaccine has made.”
Cheng said any extremely rare side effects that only come out in, for example, one in a million people, will also start to show.
“That doesn’t mean if something happens to those one in a million people that it will change the risk-to-benefit consideration, but we do want to know about that so that we can tell people ‘these are the things that could happen’.
“As the year goes on, we will also learn more from those countries about how long the protection from the vaccine lasts, and whether it wanes over time.”
