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Photo: Getty Images
Photo: Getty Images

ScienceNovember 11, 2020

Siouxsie Wiles: The vaccine news is great, but here’s the catch

Photo: Getty Images
Photo: Getty Images

How would this promised Pfizer vaccine get from the factory to being administered? Does this mean we can stop doing things to stop Covid-19 transmission? And what does 90% effective really mean? Siouxsie Wiles takes on some important questions around this promising development.

It’s all go on the Covid vaccine front this week. While the Brazilian clinical trial of Sinovac Biotech’s CoronaVac vaccine has been suspended after a “severe adverse” event, Pfizer has announced one of its vaccines is looking like it is 90% effective. The Pfizer vaccine is the one the New Zealand government has already signed a binding agreement to secure doses for 750,000 people. 

Sinovac’s CoronaVac vaccine is an inactivated version of the SAR-CoV-2 virus responsible for Covid-19. As I write this, there’s not much information available about the suspension of the CoronaVac trial in Brazil. We’ve had a couple of suspensions like this already for other vaccine candidates but CoronaVac trials in Indonesia and Turkey are still going at the moment. Hopefully we’ll find out more soon.

Pfizer’s vaccine, BNT162b2 (licensed from BioNTech), is quite different from CoronaVac. It consists of the genetic material that codes for a specific part of the SARS-CoV-2 virus. The idea is that by introducing this genetic material into our body, our cells will read the code and make the protein for our immune system to see. As I’ve explained before, the advantages of this approach are that it is really quick to develop vaccines like this and really easy to upscale and manufacture. But the main downside is that no vaccines developed using this technology have yet been approved for use in humans. 

BNT162b2 is currently undergoing phase III human trials and Pfizer has just announced a preliminary analysis of the data. According to their press release, their vaccine was found to be “more than 90% effective in preventing COVID-19 in participants without evidence of prior SARS-CoV-2 infection”. The trial is a multi-centre, multinational, randomised, blinded, placebo-controlled trial testing two shots of the vaccine, given three weeks apart. What that means is that people in multiple places in multiple countries are being randomly allocated to receive the vaccine or a placebo and no one will know who was given what until the end. You can read the trial protocol here

There are a couple of important points to note. The first is that the trial is for people over the age of 12, and they are divided into three age categories: 12-15, 16-55, or over 55. Given how age is one of the main factors that determines whether someone is more likely to have a rough time with this virus, I would have preferred to see the over 55s split up further. The second point to note is that the main endpoint of the trial is whether people develop Covid-19 from one week after they received the second dose of the vaccine.

So far, 43,538 people have been enrolled in the trial and 38,955 have received the two doses of either the vaccine or the placebo. At the moment we don’t know how many people fall into each age category, just that 42% are from “diverse backgrounds”. The preliminary analysis being reported by Pfizer is of the 94 cases of Covid-19 that have been confirmed in their trial participants within a week of getting their second dose. From that they’ve reported the vaccine is 90% effective, but we don’t know if that means for all ages of participants. The question I also have is what happens in the weeks and months after people receive their second dose? At the moment it looks like they’ll also analyse the data from two weeks after the second dose. 

Will the vaccines be as good as they need to be?

A vaccine that’s 90% effective sounds really good, doesn’t it? But what does a vaccine being effective actually mean? To me, a really effective Covid-19 vaccine needs to do three things: stop people being infectious, stop people getting infected, and stop people getting really sick and dying. 

Yet none of the current phase III trials are actually designed to test any of those outcomes. They aren’t measuring hospital admissions, intensive care admissions, or deaths. They also aren’t measuring whether the vaccines interrupt transmission of the virus. There’s a really good article in the BMJ that discusses all this. The main problem is that in the trials, a lab-confirmed infection even with only mild symptoms qualifies as meeting the primary endpoint definition. And each of those confirmed cases brings the trial one step closer to completion. 

At the moment we don’t know how severe any of the 94 cases in the Pfizer trial were. The trial will stop enrolling when they get to 164 confirmed cases. What we must be prepared for is the possibility that once a vaccine starts to be rolled out to hundreds of thousands of people, it may well turn out to not be as effective as we’d like.

Pfizer’s announcement is good news, but it doesn’t mean you’ll get a vaccine any time soon

My main worry is that Pfizer’s announcement is going to leave some people thinking a vaccine is going to be rolled out pretty soon and that’ll mean they don’t keep doing everything they can to get transmission under control. Things are certainly moving fast, with Pfizer saying in their press release that they plan to submit an emergency use authorisation to the US Food and Drug Administration soon after the “required safety milestone is achieved” some time in late November. They also say that they expect to be able to produce 50 million vaccine doses this year and up to 1.3 billion doses next year. Given people need two doses, that’s only enough for about one in 15 people globally. 

On top of being able to produce enough vaccine, there is also the big issue of how to distribute it both around the world and then to everyone within a country. The logistics of having enough needles, syringes, and people able to safely administer a vaccine are mind-boggling, and Pfizer’s requires a very tricky cold chain to get it from the factory to your arm. It needs to be kept at a whopping minus 70 degrees Celsius. Expect the price and demand for ultra-cold freezers to start going through the roof.  

Keep going!
vaccine covid injection syringe
vaccine covid injection syringe

ScienceNovember 10, 2020

New Covid-19 vaccine could protect up to 90% of people from the virus

vaccine covid injection syringe
vaccine covid injection syringe

A potential Covid-19 vaccine is showing promising signs during overseas trials, and 1.5 million doses could arrive in New Zealand as early as the start of next year.

A potential vaccination for Covid-19 that’s been tested on 44,000 people is being hailed a success as early trials show it working in 90% of patients.

University of Auckland vaccinologist Helen Petousis-Harris said the vaccine is a huge step in the fight to eliminate the virus, and a good sign for New Zealand. The government signed an agreement last month with the vaccine’s creators, Pfizer, meaning, if it’s approved, 1.5m doses of the vaccine are due to arrive in the country early next year.

“While RNA vaccines are new and none have ever been approved for widespread use in people, there are no downsides to them that I am aware of, other than the current need for most of them to be stored at -70 degrees Celsius,,” she said in a statement. “So far this vaccine pushes all the right buttons to be successful. This is very good news indeed.”

The vaccine, which is given in two doses, is RNA-based. According to the University of Cambridge PHG Foundation, RNA vaccines work by “introducing an mRNA sequence (the molecule which tells cells what to build) which is coded for a disease specific antigen, once produced within the body, the antigen is recognised by the immune system, preparing it to fight the real thing”. (Here’s a good infographic that breaks it down, from the BBC.)

Testing is still in early stages though, and experts are warning the vaccine may have side effects that have not been noticed yet. Petousis-Harris said we don’t yet know how long the effects of the vaccine last, or whether it prevents severe disease. Some people on the trial have reported flu-like symptoms, but she said this isn’t unlike the effects of some other, common vaccines like the flu shot.

“The safety looks fine so far, nothing serious, but quite a few people receiving the vaccine can feel a bit flu-ish after for a while as their body makes an immune response – not enough to put them off getting two doses in the trial, and not unlike quite a few other routinely used vaccines.”

The Covid-19 testing facility in Ōtara town centre, Auckland on August 14 (Photo: Fiona Goodall/Getty Images)

Covid-19 has so far killed 1.26m people worldwide, and caused immeasurable destruction to world economies and personal wellbeing. The US pharmaceutical company Pfizer, and its vaccine study partner company BioNTech SE, which together created the vaccine, have welcomed the success of the initial trials, saying today is “a great day for science and humanity”.

In a statement, Pfizer CEO Dr Albert Bourla said “we are reaching this critical milestone in our vaccine development program at a time when the world needs it most… With today’s news, we are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis”.

Research, science and innovation minister Megan Woods said delivery of the vaccine in New Zealand could happen as early as the first quarter of 2021, subject to further trials overseas. 

“Medsafe is working to optimise its processes so that any promising vaccines will be fully assessed as quickly as possible against the same criteria used for all other medicines that enter New Zealand.

“Pfizer and BioNTech will keep us up to date as to when data will be available for Medsafe to begin its evaluation process.”

The 1.5m doses will be enough to vaccinate 750,000 New Zealanders, and Woods says those at high risk of contracting, spreading or suffering serious health consequences from the virus will be prioritised for these initial doses.

“Ensuring equity of outcomes is a key measure of success, including protection for Māori, Pacific peoples and our most vulnerable population groups, such as older people, disabled people, health workers, essential workers and border staff.”

UK prime minister Boris Johnson said a vaccination programme is ready to be rolled out in Britain, and announced Britain has stockpiled enough doses for a third of the population.

“If the Pfizer vaccine passes all the rigorous safety checks and is proved to be effective then we will begin a UK-wide NHS led programme of vaccine distribution,” he said at a press conference. 

US president Donald Trump tweeted that the vaccine news was “great”, mentioning the stock market had boomed since the news was announced.

https://twitter.com/realDonaldTrump/status/1325778096151203843

US president-elect Joe Biden said the news was excellent but did not change the fact that face masks, social distancing and other health measures would be needed well into next year, reported Reuters.

Global markets surged on the news, reported AP, with the S&P 500 rising 3.7% after the opening bell, and the Dow Jones Industrial Average up more than 1,300 points. Pfizer jumped more than 9% and other vaccine stocks were up as well.

Pfizer expects to produce up to 50 million vaccine doses globally in 2020 and up to 1.3 billion doses in 2021. The company has cautioned that the projected success rate may shift as further trials are completed.

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