Vaccinating against a shape-shifting virus
Will the new vaccines be effective against the new strains of COVID-19 that have appeared? The short answer is ‘probably’.
The last year has shown us what humans can achieve in what seems an impossibly short amount of time. The new COVID-19 vaccines have been produced in record time, but now there is a new danger to contend with – new strains of the virus which have appeared in at least 31 countries around the world.
On January 10, 2020, Chinese scientists uploaded the genetic sequence of a novel coronavirus, later named SARS-CoV-2 and more commonly known as COVID-19, to an open-access website.
Scientists all over the world began looking at its structure, how it enters human cells, how to treat its ill-effects and, most importantly, how to create a vaccine against it.
How it works
Traditionally, vaccines work by showing our immune systems a “foreign” item such as a virus or bacteria that we may later encounter in the community.
The aim is to train our immune systems to recognise these viruses or bacteria as “other” and create immune cells against them that will reactivate when we come across them in real life, killing them before they have a chance to make us ill.
Older vaccines have used weakened forms of viruses (measles, mumps, rubella) or dead viruses (polio or hepatitis A) to initiate this response.
More modern vaccines are made up of key parts of the viruses or bacteria that trigger an immune response (meningitis C and HPV vaccine).
Some of the newest vaccines, including the Pfizer-BioNTech and Moderna vaccines, use mRNA technology (or messenger RNA – a single-strand molecule of RNA that corresponds to the genetic sequence of a gene). This instructs a vaccinated person’s cells to make viral proteins which then trigger the immune response.
The Oxford-AstraZeneca vaccine uses a genetically modified version of a virus that causes the common cold in chimpanzees but is harmless in humans. The modified virus contains genetic material which again programmes cells to produce a protein, which the body recognises as foreign and sets off a similar immune response.
A new setback
When the Pfizer and Oxford-AstraZeneca vaccines were approved for widespread use in the UK, and with the Moderna vaccine gaining approval in the US, there was a sense of relief from the medical community. After months of fighting this new illness, the untold damage done to the world’s economy and, most importantly, the deaths caused by the coronavirus, we now had hope: vaccines that work.
But in December 2020, news broke in the UK that appeared to take the shine off this new hope.
A new variant of the coronavirus – known as B117 – had been identified in the South East of the country: one that is up to 70 percent more infectious than the one it had mutated from.
The new variant does not appear to cause more severe illness in those infected by it, but it has been responsible for a surge in coronavirus cases in the UK, along with the accompanying scenes of ambulances queueing outside overwhelmed hospitals and pleas for help from exhausted National Health Service (NHS) staff.
To make matters worse, the new strain is spreading. Since December, it has been identified in many other countries as well, while other new strains have been discovered in South Africa and Nigeria.
So far, there has been no definitive answer as to whether the new vaccines will be completely effective against these new strains. However, the consensus so far is that they very probably will.
The UK’s chief medical officers have stated that there is no reason to believe the new vaccines will not work against the new variants of the virus. Dr Ugur Sahin, BioNTech’s chief executive, also told the Financial Times in London that he believes the pharmaceutical group’s existing COVID-19 vaccine, developed with Pfizer, will still be effective against the new variant.
On the whole, vaccines have been very effective against viruses and their variants in the past. For instance, the smallpox virus was eradicated because it did not mutate beyond the scope of the smallpox vaccine and, to this day, no strain of the measles virus has ever arisen that can beat the immunity triggered by the measles vaccine.
However, vaccines are not all bullet-proof. Some illnesses, including HIV/AIDS and malaria, have evaded vaccines as the organisms that cause these diseases evolve so fast.
How mutations arise
New strains of a virus arise because of mutations which occur in the original virus. Mutations are randomly occurring changes in the genetic makeup of a virus that usually occur because of errors during the replication process.
The longer a virus is able to replicate inside a host, the greater the chance that an error or mutation will take place. Of the 17 mutations identified in the new UK variant, eight affect the spike protein of the virus. The spike protein is the key with which the virus unlocks the doors to our human cells and enters them, causing them to be infected.
One of these mutations is considered especially significant – the N501Y alteration. This is believed to help the virus become more infective (able to establish an infection) and enter human cells more readily.
Large parts of the spike protein remain unchanged in the new variant, however. The immune response stimulated into action by the new coronavirus vaccines trigger immune cells that attack different parts of the spike protein at the same time, including the parts that remain unchanged.
So, while it is possible for a single part of the virus to mutate and escape being targeted, if many sites are being attacked at once by our immune system, escape from our immune system altogether would require many separate escape mutations to occur simultaneously, which is highly unlikely. For this reason, the new vaccines are still considered to be effective.
Will the vaccines still work?
Scientists, therefore, are optimistic that the new COVID-19 vaccines will work against new strains, and they stress that work in this area continues.
Time is now of the essence. The longer the coronavirus is able to run rampant through populations, the greater the chance of further mutations occurring if the pandemic does not come under adequate control by governments around the world.
It is likely that, in the future, we will see mutations that change the spike protein of the virus more substantially causing our immune system to stop “recognising” them, thereby reducing the effectiveness of the current vaccines.
One major benefit of the new mRNA technology in vaccines is that it can be adjusted reasonably easily to mimic any new mutations that may occur in the future. Dr Sahin, BioNTech’s chief executive, has even gone as far as saying that the firm could manufacture a new vaccine in six weeks if needed.
Such “tweaking” of vaccines to adapt to new strains is not a new idea. Flu viruses are constantly changing and, although it does not use the same technology, the flu vaccine composition is reviewed each year and updated as needed based on which new flu strains are likely to make people sick that year. This is why those who require the flu vaccine will need a new shot every year.
The priority – getting the pandemic under control
Although the new variant of the coronavirus has not beaten our vaccines yet, if governments do not work at getting the current outbreaks under control, COVID-19 will have an opportunity to mutate again and again, increasing the chances of an “escape” mutation which will need a vaccine “tweak”.
This is a global effort now; it is no good if a handful of the richest countries vaccinate their populations and give themselves some breathing space because the virus will find breeding grounds in less affluent countries and may well mutate there, only to reinfect those who have been vaccinated.
Collective thinking is required and now, more than ever, we need leaders who will steer us out of this global pandemic.