The flu virus mutates so fast we need to tweak the vaccine every year. And while it’s a concern that Covid could throw up a new variant resistant to our vaccines, Danny Altmann, a professor of immunology at Imperial College London, thinks there’s little chance the virus will mutate leaving our vaccines ineffective.
Coronavirus seems to evolve at a slower rate than flu. “It’s quite a sluggish virus,” Altmann says. For comparison, the measles virus hasn’t dodged the immunity triggered by the measles vaccine which is 60 years old and still going strong. Our Covid vaccines might do the same.
If we measure the efficacy of vaccines in terms of their ability to prevent illness serious enough to warrant hospital admission, the variants of Covid which have emerged so far are still sensitive to our vaccines.
So confident is Pfizer that it recently announced its vaccine is effective against a virus which carries a mutation common to both the UK (Kent) and South African variants.
Spread of the virus facilitates the emergence of new variants. The longer a virus circulates, the more people it infects, the more it can mutate. So one of the ways to lower the chance of mutation is to contain the spread, then the virus has less chance to multiply inside our bodies. A virus like Covid which mutates comparatively slowly could be contained with annual boosters to keep up with any new mutations. So how long will the vaccine protect people for?
As yet we don’t know. We might have to get booster shots every year or every other year, like the flu shot. Or it may confer longer-term immunity, as vaccination does for measles or polio, because those viruses don’t mutate readily. If we’re lucky, immunity from a single jab might last as long as with polio and measles.
Here’s some good news. A new study from the Department of Biology and Centre for Infectious Diseases at The Pennsylvania University suggests that once enough people have gained immunity from Covid-19 – either through vaccination or natural infection – the virus may become “no more virulent than the common cold”.
In the future it may come to resemble the other cold viruses, in that once you’ve been exposed to it in childhood, it will cause only mild symptoms or no illness at all.
Altmann predicts Covid-19 could be reduced to seasonal outbreaks like flu, or it could become rare. And, like flu, every winter there’ll be people who die of Covid, with many patients in hospital and the world will accept it.