VACCINE roll-out in a growing number of countries should eventually allow life to return to normal, but it is unlikely that we will be able to eradicate the coronavirus that causes covid-19 altogether.
鈥淚 don鈥檛 see that these vaccines will be eliminating SARS-CoV-2 any time in the coming years,鈥� says Kingston Mills at Trinity College Dublin.
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Despite the many variants, the coronavirus mutates less than many other viruses. 鈥淚t does not seem to be as mutable a virus as influenza,鈥� says Mills. That means we shouldn鈥檛 need to update vaccines every year, although occasional tweaks might be required.
Despite this, wiping out the virus will be really hard even if we manage to vaccinate most people. To stop a disease spreading, infected individuals must pass it on to less than one other person on average.
Early in the pandemic, infected people were infecting around three others on average, leading to estimates that two out of three people, or 67 per cent, need to be immune to halt transmission. This is what we mean by herd immunity.
Some people now think , especially with more transmissible variants. This could be hard to do. Some covid-19 vaccines don鈥檛 reach this level of effectiveness when it comes to preventing disease.
What is more, it isn鈥檛 yet clear to what extent any of the vaccines prevent transmissible infections, as opposed to merely preventing symptoms, although this is still being investigated.
鈥淓ven vaccinating everyone on the planet might not stop the coronavirus circulating鈥�
A few vaccines, such as the one for whooping cough, prevent symptoms, but don鈥檛 block transmission, says Mills.
This means that viruses 鈥� or bacteria in the case of whooping cough 鈥� can circulate largely undetected, popping up only when they spread to unvaccinated people and cause disease.
In other words, even vaccinating everyone on the planet might not be enough to stop the coronavirus circulating at low levels, and we are unlikely to get close to this.
In some countries many people say they will refuse the vaccine, such as France, where only 4 in 10 people want it. And no vaccine is yet approved for people aged under 16, who make up a quarter of the world鈥檚 population.
However, we don鈥檛 have to rely entirely on vaccines to achieve herd immunity. A study by Susan Hopkins at Public 91色情片 England and her colleagues suggests that natural infection with the coronavirus provides comparable protection, reducing the risk of reinfection by 83 per cent for at least five months.
Even if we did manage to eradicate the virus in humans, it might lurk in animals and jump back into people later on. SARS-CoV-2 including cats, dogs, ferrets, bats, hamsters, deers and tree shrews.
鈥淚 think this virus is here to stay,鈥� says Hopkins, who points out that the smallpox virus is the only one we have managed to eradicate, and that took many years from the start of the campaign to eliminate it.
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