YYou have probably read a lot about the new strains of coronavirus circulating around the world today, from Brazil to South Africa. vaccination programs. But unlike some of those scary headlines, the reality of when and why SARS–CoV–2 (ie, the new coronavirus) mutates and what it means for vaccines is much more nuanced – and it’s probably not doomsday as some news might make you believe. We talked to leading virologists to find out everything you need to know about the different strains of COVID-19, and here’s what they have to say:
How and why viruses mutate
When you get sick with a virus like the new coronavirus, “it’s not really a single virus [particle] that infects you. It’s a virus population, ”explains Richard Kennedy, PhD, virologist and vaccine researcher at the Mayo Clinic in Rochester, MN. You can be infected by 100 or even 10,000 different viral particles. Each particle has its own slightly different genetic code, just as two people have slightly different genetic codes.
Changes to this code happen only when the virus replicates – that is, it copies itself to survive. In order to replicate, a virus needs two things: a human cell (whose machinery it modifies to help it replicate) and a specific enzyme it brings in to copy its genome (essential for the replication process). This enzyme acts as a cheap photocopier, explains Dr. Kennedy. “This copier is not really a good one. He makes mistakes left and right ”, he adds. These genetic errors end up being encoded in the genome of all new viruses created in that single infected cell.
These errors happen quite regularly and at random. Many come and go because they give the virus no real advantage; some even make the virus less able to infect a cell. “Most mutations are expected to have no impact on the function of the virus or how we experience it,” says Lucy van Dorp, PhD, a specialist in pathogen evolution and a senior researcher in the Department of Genetics at University College London, Evolution and a Half environment.
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Sometimes, however, a mutation creates an advantage for the virus. “Perhaps the virus can infect other cells faster or fix itself in the cells a little better. It survives in the environment a little longer or produces more viruses ”, says Dr. Kennedy. Since all variants of the virus are trying to compete for the same number of cells that can be infected in a person’s body, beneficial mutations allow one variant to outperform other viruses. Eventually, this strain becomes the predominant variant in a person’s body – and it becomes the variant that spreads to other people, says Dr. Kennedy.
How much a particular mutation spreads depends on several factors, explains Dr. Kennedy, including how beneficial the mutation is to the virus and how many people can potentially catch the variant. “Most are not going anywhere,” he says. “It’s the [variants] that appear, then they are at 5 percent, 10 percent, 90 percent – these are the ones we are concerned about, because it suggests that they have an advantage and that is why they are spreading through the population. ”And given that, to date, there have been more than 27 million cases of coronavirus in the United States alone, which gives the virus plenty of time and opportunity to mutate – and for those most beneficial mutations to thrive.
The different strains of COVID-19 that scientists are looking at
Scientists around the world track mutations (known as genomic surveillance) at different rates. The United Kingdom, for example, currently sequences the genome in 47.3 out of 1000 COVID-19 cases, while the United States sequences 3.23 out of 1000 cases. Tracking the virus’s genome allows scientists to quickly identify and isolate new variants and update vaccines accordingly.
There are three strains that the United States Centers for Disease Control and Prevention (CDC) are actively observing, as they have all been found in the United States and so far appear to spread more rapidly than other variants.
United Kingdom (UK) variant B.1.1.7
First sequenced last fall and found in the United States in December, some researchers say the UK variant is 50 to 75 percent more transmissible than the original virus. “We are paying close attention because it has several mutations in the peak protein,” says Dr. Kennedy, referring to the unique structure of the protein on the outside of the coronavirus that is used to penetrate and infect cells. “There is some evidence that makes this variant more transmissible – that infected people have more viruses and their viral load is higher,” says Dr. Kennedy. In fact, a January report from the CDC estimated that, without further measures to control its spread, the UK variant could become the predominant variant in the United States in March.
Some researchers in the UK initially reported that this variant could be 30 to 40 percent more deadly than the previous variants, although these studies are small and inconclusive. “Time will tell as we accumulate more information about the virus,” says Dr. Kennedy.
South Africa variant B.1.351
The South African variant shares some mutations with the UK variant. Some researchers have also expressed concerns about their ability to escape antibodies (proteins released by the immune system to attack external invaders such as viruses), which potentially reduces the effectiveness of current vaccines.
“The South African variant has at least three mutations, and they are right where the peak protein binds to the cell receptor,” says Dr. Kennedy. “That is [the area] where neutralizing antibodies, either from infection or vaccination, target. ”The concern, he says, is that mutations at that crucial site of the virus may help you avoid antibodies. If this theory works, it could mean that our current vaccines are not as effective (since they generate antibodies that may not be effective against this mutation), then you can be reinfected with this variant, even if you have already been sick or vaccinated against COVID-19.
Variant P.1 from Brazil
With more mutations than the UK or South Africa variant, the Brazilian variant may be better at avoiding antibodies produced by the body to eliminate it, which could make the virus more deadly. “The variant from Brazil has exactly the same three mutations in the spike protein [as the South African variant], so it is likely that we will also see a decrease in the neutralization capacity of this one ”, says Dr. Kennedy. “As soon as we start vaccinating, if it starts to escape some protection from the vaccine, it will probably still circulate a little in the community. But what happens if more mutations accumulate? That is always the concern. “
What does this mean for vaccines
Everything about the new variations sounds worrying, but scientists emphasize that the different strains of COVID-19 should not keep ordinary people awake at night. In fact, some experts argue that we just don’t have enough data yet to know how these new variants will affect us, period. “Neither the increase in transmissibility nor the fatality of new variants of the virus has been proven,” says Theodora Hatziioannou, PhD, a virologist at Rockefeller University who is studying the new variants.
Here is a summary of how vaccines work – including some of the newest COVID-19 vaccines:
Likewise, there is mixed evidence that these strains of COVID-19 may affect the effectiveness of available vaccines. In January, biotechnology company Novavax reported the results of phase three coronavirus vaccine tests. His vaccine was nearly 90% effective in the United States and the United States, but only 60% in South Africa. “Part of that may be due to different populations and different underlying health conditions,” says Dr. Kennedy. “But it could also be because the South Africa variant was present.” Results from Johnson & Johnson’s phase three clinical trials show that its single dose vaccine was 72 percent effective in the US, but 57 percent effective in South Africa, where, the company noted, 95 percent of COVID cases -19 were associated with the South Africa variant at the time of the trial. And AstraZeneca only halted the launch of the vaccine in South Africa after its test concluded that the injection provided “minimal protection” against mild to moderate cases.
“There are already some data that suggest that vaccines will not be as effective. But the other side is 57 to 66 percent, it is much better than 0 percent, ”adds Dr. Kennedy.
For now, the CDC says that antibodies produced by existing vaccines appear to recognize the main variants and, therefore, would be able to fight them. However, more studies are underway to better understand the effectiveness of vaccines in use and development against these strains. In addition, pharmaceutical companies are developing new vaccines to address the South African variant, while the Food and Drug Administration (FDA) is preparing a rapid review process for rapid approval of booster doses if current vaccines prove to be ineffective. against new variants of the coronavirus.
“It will be a continuous race. What is likely to happen is, just like influenza, we may have to make regular changes to the strain of the vaccine used, so we may need to get a COVID-19 vaccine every two years. They will just keep changing to keep up with the mutations, ”says Dr. Kennedy. There are also good reasons to expect existing vaccines to still control the pandemic. The Johnson & Johnson phase three trial, for example, found that people who fell ill after vaccination had less serious illnesses.
How to protect yourself
At best, approved vaccines will continue to be mass produced and rapidly distributed, while scientists feed a continuous stream of new and improved vaccines. The problem remains that scientists are still unsure whether vaccines prevent the virus from spreading. “You may still have a virus in you and be able to transmit it, but you just don’t have any symptoms. This is especially true due to the fact that this virus is mutating and is already avoiding at least part of the immune protection ”, says Dr. Kennedy.
Since the only time the virus can mutate and produce new variants is when it infects a person, the only way to prevent new variants from appearing and spreading is to reduce transmissions, says Dr. Kennedy. This means that it is essential for all of us to continue masking (or even double masking for greater protection) and social detachment, even if we have already been vaccinated. “It is painful, irritating and uncomfortable, but if we want to beat this pandemic, this is basically the only way to do that,” says Dr. Kennedy.
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