It seems like we’re learning a lot in a very short space of time about viruses and immunity. Happily, this might lead to breakthroughs in all sorts of areas.
We tend to think of immunity as something of an absolute – either we’re immune to a virus, or we’re not. But that hides a world of complications, says Danny Altmann, professor of medicine and immunology at Imperial College London. The genes that control our immunity are among the most diverse in the human body, he says, differing hugely from person to person.
But what explains this natural immunity? The most likely theory is that these people’s immune systems have already been exposed to similar viruses, years or decades earlier. Sars-Cov-2 is one of a family of seven human coronaviruses, most of which cause the common cold. All of these viruses look fairly similar. When your T-cells learn how to fight one, they get better at fighting them all, it is thought.
Another, less well-researched answer lies in our genes. Some people might simply be born with an immunity to certain viruses, scientists suspect.
If it turns out that some people are indeed naturally immune to Covid, it’s wonderful news for them. But it might also help the rest of us, speeding up development of a pan-coronavirus vaccine capable of defeating any variant. The current generation of Covid vaccines were all designed to target the spike protein, on the virus’s outer edge. But the spike protein also changes frequently, each time the virus mutates. This means vaccines are slightly less effective against each new variant.
But natural immunity appears to work differently. In the UCL trial, researchers looked carefully at the blood of those volunteers who seemed to have pre-existing immunity to the virus. Rather than targeting the spike protein, their T-cells were targeting proteins at the centre of the virus. These proteins are much less likely to change from mutation to mutation. In fact, they tend to be found in most coronaviruses, not just Sars-Cov-2. If a vaccine could be built to target these inner proteins, it might just be able to defeat all variants – as well as a range of other coronaviruses.