Hope for normality
Vaccines are the way out of this pandemic, but will people be willing to take them?
I admit it – I’m one of those complacent people who weren’t scanning their QR codes with the NZ Covid Tracer app. At a guess, I had probably recorded only about 20% of the places I’d been, until last Sunday. Like many New Zealanders, I’m now doing a much better job, and I think I’m now remembering more than 95% of the time. It’s ironic, though, because it’s only a month since I wrote an article explaining that Covid-19 is even worse than the statistics suggest.
That I should have been so complacent is not as surprising as you might think. Even people like me, who work in the field of risk assessment, tend to default to our instincts when we judge risk in our own day-to-day lives. I’ve talked before about how we judge risk instinctively, when I previously talked about vaccines. To recap briefly, we think about factors such as how familiar something is, how much control we have and whether we can remember any memorable examples of things going wrong, rather than how likely something is to kill or hurt us. In the case of Covid-19, I think that many of us are starting to get used to the risk, and so we’ve become complacent.
When Covid-19 was detected again in the community in New Zealand, after three people contracted it while in managed isolation, it was a nasty shock. However, it does seem, so far, as if contact tracing and testing will be sufficient to get us through the danger and for our lives to return to almost normal. Almost but not quite normal, of course, because the threat at our border is greater than it’s ever been. Overseas, the pandemic still rages and in many countries a return to normal is almost unimaginable – or it would be without a vaccine. Now, with a number of vaccines developed and approved in record time, there’s finally hope.
But developing vaccines and getting them through the regulatory approval process is only part of the solution. A vaccine does nothing unless it’s actually administered, and that is far from a simple matter. As well as issues with manufacturing and distribution, many people are simply reluctant to get the vaccine, despite the threat of Covid-19. A recent study of more than 13,000 people in 19 countries found that 70% said they would be willing to get vaccinated if the vaccine was proven to be safe and effective. On the other hand, significant numbers were unwilling. While very few in China said that they weren’t willing to be vaccinated, there were several countries where the number who were unwilling was around 20% or more, including France, Nigeria, Poland, Russia and Singapore. In addition, significant numbers were just unsure; a study conducted in the UK and Ireland found that around a quarter of people were uncertain whether they would get vaccinated or not. Around 30% of New Zealanders have become more concerned about the safety of vaccines over the last decade, so it’s likely that there will be similar concerns about the Covid-19 vaccine here as well.
So what is going on? Are people right to be worried?
Concern about the safety of vaccines is nothing new. As I mentioned in one of my earlier articles, many people in eighteenth and nineteenth century England were reluctant to trust Jenner’s vaccine against smallpox. Despite the much greater risks, many people preferred the older practice of variolation, which killed one in a thousand of those inoculated. Some even decided to take their chances against the disease itself, which was, at that time, killing one out of ten people in London.
New Zealand is one country which has continued to have difficulties convincing people to get vaccinated. In New Zealand at the end of the nineteenth century, vaccination rates against smallpox were consistently under 50%, even though vaccination was, theoretically, compulsory. The diphtheria vaccine was routinely offered for children under seven from 1941, but rates were still below 70% in the 1950s. In the 1980s, fewer than 80% of children received all their recommended vaccinations, and although this number has risen to over 90% at times, it’s now around 88%. Only a quarter of New Zealanders got vaccinated against the flu in 2019, and only a third in 2020.
While concerns about vaccine safety aren’t the only reason for New Zealand’s low and declining vaccination rates, they are a part of it. As I discussed in another of my previous articles on vaccination, we cannot afford to ignore these concerns, especially in the case of Covid-19, when we know that vaccines have been developed in record time. So I’ve decided to take a closer look at the main vaccines against Covid-19, to better understand what they are, how they work and just how safe they really are.
Vaccines work by imitating an infection with viruses or bacteria. In responding to the imitation infection, the body makes white blood cells which produce antibodies, which in turn attack those specific viruses or bacteria. Enough of these white blood cells remain in the body so that when the body encounters the viruses or bacteria again, it can make antibodies quickly, before any disease can take hold.
There are many different ways that vaccines imitate infection. Traditional vaccines imitate an infection by containing viruses or bacteria which are weakened or dead, and therefore are unable to cause disease. The vaccine given against measles, mumps and rubella (known as MMR) contains live, weakened viruses, as does the oral polio vaccine. The injected polio vaccine and the Sinovac coronavirus vaccine from China both contain dead viruses. (More correctly, viruses are said to be inactivated, since they aren’t strictly living things – more on that later.) In general, dead or inactivated vaccines are safer, but they usually require multiple doses. Live vaccines are very effective and don’t usually require multiple doses, but they cannot be given to people with compromised immune systems, such as people undergoing cancer treatment.
Many modern vaccines contain only part of a virus or bacterium – just enough to convince the body it is infected so that it mounts an immune response. In general, these vaccines are safer than whole virus vaccines and they are also usually very stable, making them easy to store. But they aren’t usually as effective at triggering a strong immune response, and often require booster shots. One of the whooping cough vaccines is of this type.
Most of the recently approved Covid-19 vaccines use newer technology again. What they do is remarkable and complex, and to understand the vaccines it really helps to understand exactly what viruses do in the human body. I’ll give a quick summary of what I wrote in a previous article, where I talked about Covid-19 testing.
Viruses are not living things – they have only their genetic material (DNA or the similar molecule RNA) and a coating that protects the genetic material. They have no ability to do what living things do – move, grow, feed or excrete waste products. Instead, they hijack the cells of a living thing so that those cells stop whatever they were doing and start making more copies of the virus.
What some of the Covid-19 vaccines do is mimic the way that viruses take over cells to create new viruses. However, instead of making new viruses, the cells just make part of the virus – enough to trigger an immune response, but not enough to cause disease. There’s a great video explaining this on the website of the Global Vaccine Alliance. The video is only four minutes long and gives a much clearer explanation of how the vaccines work than I can write on a page.
Both the Pfizer/ BioNTech and Moderna vaccines tell the cells to make parts of the Covid-19 virus using a molecule called messenger RNA. Messenger RNA is, as its name suggests, a communication molecule – its job is to carry pieces of genetic code from the place where they are stored, the cell’s nucleus, to the place where the genetic code is translated to make protein molecules, the ribosome. When a messenger RNA vaccine enters a cell, it carries a code which tells the cell’s ribosomes to make parts of the virus, which the body recognises as something that doesn’t belong there, so it mounts an immune response.
The Oxford/ AstraZeneca vaccine works in a similar way, but the code to make parts of the Covid-19 virus is carried inside another virus which has been weakened to make it harmless.
It’s no accident that the two messenger RNA vaccines were the first to be fully tested and then approved. The great advantage of this kind of vaccine is that the manufacturing process is short. To make more traditional vaccines, you need to grow large amounts of virus, something which must be done by culturing live cells and then infecting them with the virus you want to grow. Because the Oxford/ AstraZeneca vaccine also uses a virus to carry the virus’s genetic code to the cell, this vaccine also requires viruses to be cultured in living cells.
The disadvantage, as we have probably all heard by now, is that messenger RNA is a rather unstable molecule and needs a lot of care to ensure that it doesn’t disintegrate before it does its job. Partly this is achieved in the way that the messenger RNA is made and what other compounds are added to the vaccine, but part of it depends on how the vaccine is stored. The Moderna vaccine needs to be stored at -20 degrees Celsius, which is the temperature of a normal freezer, while the Pfizer/ BioNTech vaccine needs to be stored at at between -60 and -80 degrees Celsius, which is almost, but not quite, colder than any natural temperature recorded on earth.
The other disadvantage, of course, is that these vaccines use new technology. While vaccines are, in general, very safe, they can still have some side effects and disadvantages. We have years of experience with traditional vaccines but what do we know about the potential for side effects in these newer vaccines? In my next article, I will look at how vaccines are tested, and what we know about the safety and side effects of the main Covid-19 vaccines.
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