Therefore, there is no way to launch a network around Covid-19 and reduce it to nothing; your animal hosts will always provide an emergency exit. However, it is not really useful to start thinking about alternative hosts until all potential human victims of a disease have been protected by vaccination – and so far, we are not even remotely close. While people somewhere in the world are still waiting for their first shots, Covid-19 will have human hosts to reproduce. And also, potentially, to mutate, creating the kind of variants that are now appearing all over the world.
This raises the possibility that, as the virus changes, we will need to continue working with vaccines to keep up with it. “I think most people think this will be something where in the next few years we will probably have a chance at Covid-19,” said Alex Gorsky, CEO of Johnson & Johnson, earlier this month at a CNBC event. “Exactly what this scene is going to be, I don’t think we know today.”
If Covid cannot be a disease that we try to eliminate quickly – the way, for example, we distribute vaccines to fight Ebola outbreaks – it needs to become a disease that we plan, like measles and flu. With measles, we started vaccinating in childhood. With the flu, we revaccinate annually, while adjusting the vaccine content to track viral evolution. We vaccinate against them because they take a heavy toll. In the past 10 years, the flu has killed 12,000 to 61,000 people a year in the United States; globally, measles kills 140,000 each year.
We have no guarantee that Covid-19, if it becomes endemic, will be as fierce as measles or become light. Before the start of the pandemic, there were six coronaviruses known to infect humans: the original SARS in 2003; MERS, which appeared in 2012; and four that cause seasonal diseases. These last four, which are now considered endemic, are responsible for about 25% of the colds we contract each winter and demonstrate that some coronaviruses can become something we don’t like, but we need not fear. (However, they were not always mild. One of them was recently associated with a worldwide epidemic in 1889 and 1890 of respiratory illnesses and neurological problems; it went down in history as the “Russian flu” – but that name was a guess in its cause, already that influenza viruses were not identified until 40 years later.)
A recent article that models the future potential of the coronavirus novel, written by postdoctoral fellow Jennie Lavine of Emory University, tries to predict how Covid-19 might behave in the future, based on data collected from the four endemic coronaviruses, in addition to SARS and MERS. He finds that Covid-19 can reach the state that the four endemic strains now occupy, from causing mild illness on a regular basis – but that outcome will depend on how the circulating disease behaves in children during their first infections, as they are the first infections that configure the immune system to respond in the future.
This is the same role that vaccines play, of course. Our bodies create various types of immunity in response to pathogens; it is too early, says Lavine, to gather the long-term data we will need to know whether Covid-19 vaccination and childhood infection protect in such a way that any subsequent infection produces only mild illnesses.
But suppose, for now, that the virus does not become a mild infection like a cold, but remains unpredictably dangerous. This perspective makes it more urgent to neutralize vaccine nationalism and distribute doses around the world as quickly as possible, not only to protect people from disease, but to deprive the virus of hosts in which it can mutate.