Infections are rising even among highly vaccinated nations as governments relax restrictions and winter returns. Is herd immunity a myth?

(Originally published Oct. 25 in “What in the World“) Covid is making a comeback. That’s right: a new surge is underway and it looks as though it we’ll be coping with it until the end of next February.

So once again human nature, not the virus, is our biggest enemy in this battle. We never even managed to get the surge in the Delta variant back down to lows we achieved in March and July. We gave up as soon as we managed to turn the tide. Cases are even surging in Germany, which was doing so well that it tempted zero-Covid Singapore out of its shell. But even its 66% vaccination rate doesn’t give it adequate protection against the virus. Now both countries are experiencing a frightening surge in new cases.

The good news (if anything about a resurging pandemic can be described as “good”) is that this surge appears so far to be taking place among holdout populations of unvaccinated people, those with compromised immune systems and, disturbingly, vaccinated people abusing their partial immunity by throwing aside precautions against infection and transmission—traveling in high-infection zones, mingling in crowded areas, doffing their masks….

So far, these are the only countries that appear to have beat Covid:

• Bahrain (a new entrant)
• Chile
• Malta
• Portugal
• Qatar
• San Marino (also new)
• Spain
• United Arab Emirates
• Uruguay

These are the only places with demonstrably sufficient herd immunity and low infection rates to justify lifting restrictions on gathering and travel. And it’s great news that two place, albeit very small ones, have joined this list since I last compiled late last month. Unfortunately, two nations that were on the previous list—Denmark and Iceland—have fallen off because of resurgent infections. And they’ve experienced these reviving infection rates despite having achieved immunization and recovery rates that should have arguably given them herd immunity.

Something ain’t working. Indeed, cases are rising again in all these top-vaccinated countries in the below chart except for Cambodia, Israel, the UAE and the United States.

Since most of these highly vaccinated nations achieved that status fairly recently, one can only suspect that the surge in infections is the result of loosening restrictions, which has multiplied the number of encounters between carriers. Since some individuals remain unvaccinated and even those vaccinated have a small chance of becoming infected and transmitting Covid, this may be the inevitable result of reopening after achieving “herd immunity.” This does, of course, defy the term of herd immunity, which is to achieve such a level of immunity in the population that a virus cannot spread because it cannot encounter enough susceptible individuals faster than those infected recover.

It therefore bears investigating whether the new statistics support that thesis or whether we need to worry that there is no such thing as herd immunity when it comes to Covid. The latest surges in Northern Europe are almost at a level of previous outbreaks. And Singapore’s experience is certainly discouraging—it’s latest outbreak far eclipses any previous despite having only opened up after achieving a vaccination rate above 70%.

We can only hope the surge isn’t the result of a new variant. Or that the newly infected don’t provide the virus the opportunity it needs to produce one. That’s why it remains so imperative that the world reimpose restrictions until infection rates subside and we can get vaccines to the vast majority of the planet that still hasn’t had access to them.