So there is no way to cast a network around Covid-19 and adjust it to nothing; your animal guests will always provide you with an escape hatch. However, it’s really not helpful to start thinking about alternate hosts until all potential human victims of a disease have been protected by vaccination, and so far, we’re not even remotely close. As long as people somewhere in the world keep 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 popping up around the world.
That raises the possibility that, as the virus changes, we will have to keep playing with vaccines to keep it up to date. “I think most people feel like this is going to be something that we will probably get a Covid-19 injection into in the next few years,” Alex Gorsky, Johnson & Johnson’s chief executive, said earlier this month at a conference CNBC. “Exactly what that take is going to be made of, I don’t think we know today.”
If Covid cannot be a disease that we are trying to quell quickly (the way we, for example, implement vaccines to counter Ebola outbreaks), it has to become a disease that we plan for, like measles and influenza. With measles, we started getting vaccinated in childhood. With the flu, we revaccinate annually, while adjusting the vaccine content to keep up with viral evolution. We get vaccinated against those because they come at a great price. In the past 10 years, influenza has killed between 12,000 and 61,000 people per year in the United States worldwide, with measles killing 140,000 each year.
We have no guarantee if Covid-19, if it becomes endemic, will be as fierce as measles, or if it will become mild. Before the pandemic began, six coronaviruses were known to infect humans: the original SARS from 2003; MERS, which emerged in 2012; and four that cause seasonal diseases. Those last four, now considered endemic, are responsible for about 25 percent of the colds we get each winter, and they show that some coronaviruses can turn into something we don’t like, but we need not fear. (However, they have not always been mild. One of them was recently linked to a worldwide epidemic in 1889 and 1890 of respiratory diseases and neurological problems; it went down in history as the “Russian flu,” but that name was a guess. in its cause, since influenza viruses were not identified until 40 years later).
A recent article modeling the potential future of the novel coronavirus, written by Emory University postdoc Jennie Lavine, attempts to forecast the ways that Covid-19 might behave in the future, based on data collected from the four endemic coronaviruses, in addition to SARS and MERS. . It finds that Covid-19 could reach the status now occupied by the four endemic strains of causing a mostly mild disease on a regular basis, but that result will depend on how the circulating disease behaves in children during their first infections, since they are the first infections that make the immune system respond in the future.
That is the same function that vaccines perform, of course. Our bodies create multiple types of immunity in response to pathogens; It’s too early, Lavine says, to collect the long-term data we’ll need to find out whether the Covid-19 vaccine and childhood infection protect in such a way that any subsequent infection produces only mild illness.
But suppose, for the moment, that the virus does not turn into a mild infection like a cold, but remains unpredictably dangerous. That prospect makes it more urgent to defuse vaccine nationalism and distribute doses around the world as quickly as possible, not just to protect people from the disease, but to deprive the virus of hosts it can mutate into.