Everyone wants immunity from the coronavirus. But there may be different ways to get it.

One is a vaccine. Clinical trials are already underway in the UK, and if all goes well, say those involved, it's possible a vaccination may be ready for production by September.

The other option is gaining "herd immunity": as the disease spreads, it's hoped enough people build up antibodies, preventing them from being infected again. The pathogen would then have an insufficient number of suitable human hosts to sustain itself, and would therefore die out.

There are risks with both approaches.

For the vaccine approach: what if trials don't go well? Even if they do, Bill Gates puts the realistic timeline at 18 months until a vaccine might actually become available to the public. Then there's the issue of scaling up production: there wouldn't be the logistical capacity to suddenly vaccinate everyone at once during the 18th month. So who goes first? And who goes last? And will vaccines solve everything anyway? There is after all a flu vaccine, and yet flu is still around.

Still, this appears to be what most governments are working towards. They will restrict our daily lives to varying degrees, and the normal workings of the economy, to try to save as many lives as is reasonably possible until scientific progress brings an answer.

For the "herd immunity" approach, put bluntly: letting the virus spread is accepting that many, many people will die. We also don't know exactly how many people become immune once they have contracted the coronavirus; in a few, it appears to return. One senior German government official said recently that about 72,000 people a day would have to be infected for 18 months for half its population to become immune – still beneath the likely threshold for "herd immunity." That, critics argue, would overwhelm any health system.

It must be stressed that herd immunity is not official Swedish policy. But many see it as a possible consequence of the country's more relaxed approach. Unlike others countries who have suffered a rapid rise in cases, the Swedish government has not implemented a lockdown. There are some restrictions on movement, and many are working from home when they can, but businesses and schools remain open, and life is far more relaxed than it is amongst many of the country's neighbours. 

Officials argue their approach is not fundamentally different from the majority of other affected countries, and that they are simply thinking more long-term. Lockdowns may spare those countries the worst effects of COVID-19 now. But what of the second wave, when their population has so little immunity by comparison with more open countries?

Then there are the devastating economic consequences of lockdowns: will governments be cash-strapped for years? Will living standards decline as a result? Will that, ultimately, cost lives and longevity too? There are already growing consequences from our physical and psychological health.

The Swedish epidemiologist I interviewed for this story believes it is highly likely that Sweden will gain herd immunity before a vaccine becomes available. Paul Franks is by no means alone in that view. Many Swedes appear to back their government's outlier approach. The head of the country's Health Agency has even suggested some of the worst-effected parts of the country could start to see some herd immunity by May.

Perhaps both approaches will work: after all, each country has its own individual geography, demography and culture. There is no "one size fits all" policy.

But Sweden is very much out on its own during this pandemic. Its outcomes will be closely watched by almost every other nation on Earth.

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