Luxembourg began rolling out vaccines against the coronavirus in December 2020 Library photo: SIP / Emmanuel Claude

Luxembourg began rolling out vaccines against the coronavirus in December 2020 Library photo: SIP / Emmanuel Claude

The European Medicines Agency on 21 December 2020 approved the first Sars-CoV-2 vaccine for emergency use in the EU, an achievement in record time that surprised even scientists. But threats to herd immunity still loom large.

Around 470,000 lives have been saved among those aged 60 years and over since the roll-out of covid-19 vaccinations began in the 33 countries of the World Health Organization’s European region, a study from last month estimates.

“We wouldn’t be this far if we didn’t have the vaccine, that’s crystal clear,” says Paul Wilmes, a professor at the Luxembourg Centre for Systems Biomedicine (LCSB) and member of the Research Luxembourg covid-19 task force.

This time last year, restaurants across the grand duchy were closed, there was a nightly curfew and only two people from one household could visit someone else at home. Theatres and cinemas were closed as were indoor gyms. The government at the end of December 2020 began rolling out coronavirus vaccines to healthcare staff and the elderly. 

“More people would be dead, more people would be suffering from the long-term effects of covid. We would be in a completely different situation,” says Wilmes. “It’s an absolute achievement of vaccines that we’ve had this touch of normality.”

Immunity diminishes over time. That’s completely normal.
Paul Wilmes

Paul WilmesLCSB, Covid-19 task force

That sense of normality, however, is under threat. The omicron variant has been spreading quickly in Europe and elsewhere. A booster shot with Pfizer/Biontech offers 75% protection from infection and early data from Moderna looks promising. But even if 100% of the population was vaccinated and received a booster jab, that would still leave 25% susceptible.

“Immunity diminishes over time. That’s completely normal,” says Wilmes. “The booster is absolutely the right tool to bring immunity to the point where you are protected against infection.” An omicron-specific vaccine could hit the market next year, but whether we will need repeated booster jabs--like an annual flu shot--remains to be seen.

“For the flu vaccine, we know more or less how the virus will evolve. We make predictions what next year will look like based on what’s circulating this year. We know how to do this because we have gained a lot of experience over the years. We’re lacking this experience here,” says Wilmes.

Transmissibility vs virulence

One of the problems is that the coronavirus doesn’t follow normal evolutionary processes, says the scientist. When a virus becomes more transmissible, it usually also becomes less virulent, causing less severe illness. With the coronavirus, this hasn’t necessarily been the case. One of the difficulties is the long incubation period, allowing someone pre-symptomatic to infect many others before falling ill. “This virus has zero interest in being less virulent.” Reliable data on the virulence of the omicron variant is still pending.

But in addition to new variants, viral recombination would be a “dramatic development.” Viruses don’t only mutate but they can also exchange genetic material. This means that different strains of coronavirus--Sars-CoV-2 among them--could form a completely new virus, a sort of Frankenstein that could infect cells in a new and different way than what we’ve seen up until now in this pandemic.

“A big discussion at the moment is to develop a general coronavirus vaccine,” says Wilmes. Coronaviruses are a large family of viruses that cause respiratory illnesses, including the common cold. There are hundreds of them. Three, Sars-CoV, MERS-CoV and Sars-CoV-2 over the last two decades have caused serious and widespread illness and death.

The development of such a vaccine, however, is much more complex, taking into account geographical differences and the broad spectrum of viruses. In addition, it will be much harder to find candidates that fit the criteria of large-scale clinical trials.

“You had a lot of people at that time who had covid and you could reach the necessary population size,” says Wilmes about the development of the coronavirus vaccines currently on the market. This allowed researchers to determine efficacy more quickly, he says. “And you could vaccinate a lot of people quickly, because they wanted to participate.”

An influx of cash into the vaccine research and clinical trials helped speed things along. And scientists had already been working on the mRNA and the viral vector-based technology used by different manufacturers. “It went very quickly,” says Wilmes, but the vaccines authorised by the EMA went through the same procedures as other medicines. “I have no concerns.” Getting infected with Sars-CoV-2 and developing covid-19 poses a much bigger risk than that of getting vaccinated, the scientist says.

Vaccine and treatment options

An 85% vaccination rate, however, won’t be the end of the pandemic, says Wilmes. Denmark had reached this rate earlier in the year and lifted all its pandemic restrictions. Curbs have since been reintroduced. The Luxembourg government had set this rate as a target to start lifting restrictions. But despite nearing the tally, it has since tightened its CovidCheck regime until at least the end of February.

Herd immunity won’t be reached through transmission alone, nor through vaccination, says Wilmes. But how do pandemics end? “How you get out is that you have a medicine that you can take early on when you’re positive,” he says.

You’re trying to find a needle in a haystack.
Paul Wilmes

Paul WilmesLCSB, Covid-19 task force

Pfizer’s Paxlovid pill reduces the risk of hospitalisation or death by 89% among adults, the company said this month. The European Medicines Agency on 16 December said countries can start treating adults with covid-19 who are at increased risk of progressing to severe disease while market authorisation is still pending.

“Developing a vaccine is comparatively easy,” says Wilmes. To develop a treatment, researchers must find exactly the right molecule that fits the structure of a specific virus enzyme. “You’re trying to find a needle in a haystack.”

Vaccination will remain key to keeping the pandemic manageable, says Wilmes. “Preventatively, it’s incredibly important.” But even though science has delivered at incredible speed, the pandemic is likely to stay with us for some time to come. “We will over the coming years, unfortunately, be in a situation where we will be chasing behind.”