How coronavirus variants threaten to undo all our progress in the fight against COVID-19

For the first time in over a year, people are beginning to feel hopeful that the pandemic is finally over. Europe is on track to be largely vaccinated by the end of the summer. Paris and New York have announced that they are reopening for business. But in reality, we are entering one of the most precarious moments of the pandemic. We are in a critical race between vaccines and coronavirus variants, and despite all the progress made in recent months, the outcome is far from certain.

Fewer than one in ten people on the planet have received even a single dose of a COVID-19 vaccine, while frightening new variants are infecting people at a record rate. And that puts all of us - even, in the worst case, the vaccinated - at risk of having to go back to the drawing board.

The situation is so alarming that public health experts and virologists seem more disheartened by the state of the pandemic than they were a few months ago, when it looked like vaccines would smooth out the infection curve. Dr James Hildreth, a leading virologist who sits on the advisory committee to the Food and Drug Administration, which approves COVID-19 vaccines in the US, has these words of warning:

It doesn't look good, to be quite honest. It's almost as if the availability of the vaccines, and the knowledge that they're coming, has caused some people to let their guard down a little too early.

Scientists who have tracked the spread of variants since the dawn of the pandemic have watched in horror as new, more infectious mutations have taken over. 'Until November, most people didn't really care about the variants,' recalls epidemiologist Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

It was just kind of a curiosity, a way to measure the age of the virus.

The big question now is whether we have seen the worst variations of this virus. Increasingly, scientists are leaning towards those who are not so sure. And this is a worrying prospect.

There are three ways in which variants could win

The bad news is that the limited pace of vaccinations gives the virus plenty of opportunities to look for loopholes to exploit in our defences. By constantly evolving and adapting to its original habitat - us - the COVID-19 seeks to survive by creating the fittest version of itself. Yet all our current vaccines were designed to combat the virus first identified in Wuhan, China, almost a year and a half ago.

This version of the virus is virtually extinct, having been supplanted by more suitable variants, including those that have been shown to be more transmissible, resistant to certain vaccines and capable of reinfecting people. B.1.1.7, the variant first identified in the UK, is now responsible for most cases of COVID-19 in Europe and North America.

The good news is that the vaccines we have are so strong that they are resistant to mutation. In addition, almost every major pharmaceutical company is scrambling to create new vaccines and boosters, in the hope that they will be one step ahead of the variants.

There are three important ways in which the virus can outwit our vaccines. First, and crucially, all the vaccines we have target the coronavirus's spike proteins, the sharp, crown-shaped bumps on the surface of the virus that help it invade our cells. If multiple game-changing mutations occur in these proteins, our current vaccines could become useless: vaccine-induced antibodies would be unable to fend off the new variants. The P.1 variant, first identified in Brazil, has three mutations on the spike protein and reinfects people who have already had COVID-19.

Secondly, there is the possibility of what virologists call 'escape mutants,' i.e. variants of the virus that are cunning enough to override the immune defences we have managed to put in place. It turns out that the current environment we have created, in which we have achieved only partial herd immunity, creates the ideal circumstances for escape mutants to emerge. The presence of large numbers of partially vaccinated people, or communities with low or declining viral immunity, can exert selective pressure on the virus, eliminating from competition the variants against which vaccines are most effective.

Viruses that can fully dodge vaccines are not necessarily that far away

Third, and perhaps most troubling, even if we are not knocked out by an escape variant or major changes in the virus' spike protein, no one knows how long our current vaccines will offer complete protection against the virus and its rapidly emerging variants. What scientists do know is that vaccine protection will not last forever, which could leave vaccinated people vulnerable to the virus again in the years to come - opening the door to another mega-wave of infections.

We will have to - probably this summer and autumn - start planning the next generation of vaccines.

The best hope

Even after a large proportion of the population has been vaccinated, immunocompromised people will remain vulnerable to COVID-19 and its lasting effects. If we don't get the pandemic under control quickly enough, unvaccinated bodies could become the perfect breeding ground for the variants. This is another reason why it is wrong to suggest that young people do not need to be vaccinated: protective coverage of only half the population will not be enough.

It is also possible that vaccinated people who are infected but never develop symptoms become discrete reservoirs of variants.

Even if the dreaded escape mutants do not completely disrupt our progress, the global outlook for the next two years remains bleak. At best, the US, Europe, Israel and perhaps a few other countries achieve vaccination levels high enough to contain the virus to occasional outbreaks, while the rest of the world continues to face a full-blown pandemic that is killing millions and disrupting the global supply chain. It is worth remembering that most of the world's vaccines are manufactured in India, where a crippling wave of COVID-19 infections has left corpses piling up so fast they are being incinerated in car parks.

This is not the future I want for the next year or two. And I don't think it's the future any of us want.

Fortunately, scientists agree that there is still much reason for hope. After decades of relentless research, new vaccines based on messenger RNA have arrived in force. The beauty of mRNA vaccine technology is that it trains the body to fight the virus on its own. This means there is no need to incubate the viruses, which is a huge time saver.

The new mRNA vaccines can literally be developed over a weekend. And considering that only two or three variants of the COVID-19 virus appear to be responsible for most of the current difficulties, it is not difficult to imagine that they could be contained by a second generation of successful vaccines. Pfizer and Moderna are already working on their boosters, and GSK is developing a vaccine that would target several variants at once.

Scientists also hope that, given all they are learning about the new variants, they will one day be able to come up with a unique cocktail of multi-coronaviruses that would withstand all threats. But even if vaccine developers were to develop such a dream cocktail - a tall order given that it has never been done - it is difficult to make such a concoction a success. By trying to train the body to fight many versions of the virus at the same time, our immune systems necessarily become less robust.

The biggest threat

Until then, the greatest threat we face is our own complacency. From a global perspective - which is the only one that matters in an epidemiological disaster of this magnitude - things are getting worse, not better. The number of COVID-19 cases reported worldwide in the last two weeks is higher than in the first six months of the pandemic. More than half of the cases reported last week were in Brazil and India, where experts fear more variants may emerge that could evade vaccines.

At this point, after spending more than a year in various states of confinement, it is understandable that people treat vaccinations as a release. In India,tens of millions of people recently went to the Kumbh Mela, one of the world's biggest festivals, and many of them fell ill. And Japan is still pushing to host the Summer Olympics this year, even though it has seen most of its COVID-19 deaths in recent months.

Right now, we are like an overconfident boxer who lets his guard down in the last round. Even if we keep the virus on the ropes, we give it a golden opportunity to strike a fatal blow. Given the low vaccination rates around the world, the urge to take off our masks and move around freely will only encourage the emergence and spread of new variants. Until we are able to achieve herd immunity, scientists say, we must understand that vaccines alone are not enough. Basic preventive measures, such as masks and social distancing, remain essential to stop the spread of COVID-19 and the deadly new variants it is rapidly developing.