As a child, I learned the fascinating fact that sometimes, when we see a star shining brightly in the sky, the light has taken so long to reach our eyes that the star has actually died since emitting that bright twinkle. This is hard to wrap our heads around; sometimes it’s hard to wrap our heads around the truth.

Infectious diseases operate in a similar way. What we see right now in disease is a fractured picture of what was happening on the front line of transmission in the past. Understanding this is relevant to the very controversial approach that the government of the United Kingdom has taken to the covid-19 pandemic. Unlike every other country in the world, the U.K. was apparently planning to accept a wave of infections, which would ordinarily be considered catastrophic, with the goal of generating “herd immunity.” The government was holding to this until Monday, even as the number of infections of the novel coronavirus and related deaths start to steadily increase, in a pattern already seen in other countries.

The logic was “to build up some kind of herd immunity” over coming weeks to prevent a hypothetical second wave in the fall that would coincide with flu season and place the National Health Service under unimaginable strain. But we have no idea if there will be a second wave or when that would occur. Fortunately, Monday saw a request for people to limit social interactions, including “working from home where they can and avoiding pubs, clubs, and other venues.” Time will tell how well these requests — not orders — are adhered to.

The idea of trying to bring on herd immunity is flawed for many reasons. One of them is the way it does not take into account the element of time. We have learned from the stars that what we see right now are a very delayed report of what was actually happening in the past.

When it comes to the coronavirus, that means that when we identify a “confirmed case,” this gives us more information about the past than the current situation. Several steps have already happened before a person is confirmed to have the disease. The first step is infection — no one sees this in real time, but it happens when contact occurs between someone who is infected and someone who isn’t. (Spoiler alert: Contact has a major role in this horror movie, and we need to give it a walk-on part instead.)

Once the virus has established itself in a person, it sets up shop, it multiplies, it works its way around the body — and, after maybe a week, it starts to make itself known. Say you get a fever, maybe a bit of a cough. You go to the doctor. By the time you get tested, a whole week could have elapsed since the actual infection.

The time lag between diagnosis and death is even longer — researchers have already established it takes about a month to die of covid-19. So in places where there has been poor testing (including the U.K., where testing is focused on those at risk of severe illness), deaths attributed to the coronavirus are telling us that transmission happened five weeks earlier. Meanwhile, the virus has been gate-crashing restaurants, bars, schools, colleges and the subway, gleefully infecting person after person through our main protagonist: contact.

Viruses don’t care which country you live in. The rest of the world (with notable exceptions) watched from afar as Wuhan, China, built a new hospital specifically for covid-19 patients, and then as parts of the rest of the nation went on lockdown. People were confined to their homes; food was delivered and made by people who received regular temperature checks. Other countries thought none of this would happen to them. But exceptionalism will cost lives.

Those “notable exceptions,” after all, had suffered badly in previous outbreaks of novel viruses — places such as Taiwan, Singapore and Hong Kong were hit hard by the SARS outbreak of 2003. They learned their lesson. This time, they have responded quickly. When they found the first cases, they knew they were seeing the past, and if they didn’t respond immediately, the future could be far, far worse.

Italy is learning this harsh lesson now: Limiting social contacts — which provide the virus with opportunities to transmit — is the only tool we have. Italian authorities enforced a national lockdown on the same day that they hit more than 8,000 reported cases and 463 deaths. This was, sadly, far too late. Five days later, there have been more than 2,100 deaths from almost 28,000 cases. And because of the skewed view we have of the real situation, things will almost certainly get worse before they get better.

But the United Kingdom has apparently decided lessons of SARS and the experiences in Wuhan and Italy do not apply in Britain. The U.K. government has said its approach to the outbreak will be to postpone enforced “social distancing” (the now well-known name for reducing your contacts to as few as possible) although a request for limited social interaction was announced on Monday. This will ensure more people get infected in this initial wave of the pandemic — British officials suggest as many as 60 percent of the population — and, hopefully, become immune.

Unless, of course, they die.

Patrick Vallance, the chief scientific adviser to the U.K. government, claims this will flatten the curve, both reducing and delaying the epidemic. Although the current statistics appear low — 1,543 cases and 55 deaths as of Monday — those are the light from dead stars, generated weeks ago, while the virus has continued to spread. Delaying social distancing will exacerbate the epidemic, the very opposite of flattening the curve.

Officials seem to be realizing, too slowly, that their approach will fail, but they’re only correcting it haphazardly. Authorities have announced that mass gatherings will be banned starting tomorrow, but very recently, events such as the Cheltenham horse race, with 60,000 attendees, and a Stereophonics concert, in Cardiff, Wales, with 5,000 fans, have taken place. These types of gatherings act as super-spreading events — the kind that resulted in a huge spike of deaths in Philadelphia in the 1918 influenza pandemic, while St. Louis controlled its outbreak with early enforcement of social distancing.

In another U-turn, the British government, which announced on Sunday that those over 70 and younger adults with underlying health conditions would be requested to stay at home in a few weeks, then requested 24 hours later that this start by the weekend. This change is very welcome and probably was the result of pressure from other scientists, although it may be too late to prevent catastrophe. Britain has 4,100 ICU beds available, which could be filled up with covid-19 patients very quickly — and that’s of course assuming none of them are already occupied by patients with other issues. Which some of them certainly are.

The British health-care system will probably be unimaginably overwhelmed, and the main cause will be the government’s policy. They are trying to manage the future, without realizing they are looking at the past.

The evidence is clear on this. Examples of how to manage this novel coronavirus are out there for all to see. When it comes to tackling this disease, the U.K. should not assume it is any different from Taiwan or Hong Kong, and definitely not from Italy. The time to act is always earlier than you think. The picture you are seeing is just the light from a long-dead star.