COVID vaccines might stop a '4th wave' in the U.S. But the rest of the world isn't so lucky.

You wouldn’t know it by following the news from the United States, where daily COVID-19 cases have fallen by 80 percent over the last 10 weeks — and where they continue to fall.

You wouldn’t know it by following the news from the United Kingdom, either. There, daily cases have plummeted 90 percent over the same period.

And you certainly wouldn’t know it by following the news from Israel, where normal life has all but resumed.

But despite the rosy view from a few select countries, the total number of COVID-19 cases worldwide is actually rising right now. In fact, after peaking on Jan. 11 and dropping by half over the next month — the first overall decline of the entire pandemic — global cases reversed course in mid-February and began to rebound.

Since then, new daily cases have climbed nearly 20 percent overall. In France, they’re up more than 30 percent. In Brazil, they’re up more than 50 percent. In Italy, they’re up more than 80 percent. In India, they’re up more than 110 percent.

The dreaded “fourth wave,” in other words, has arrived — even if it hasn’t arrived in the U.S.

These divergent trajectories offer up a troubling preview of the next phase of the pandemic, and they should trouble everyone, including residents of countries like the U.S., the U.K. and Israel, where the virus finally seems to be retreating.

A man leaves the vaccination center
A man leaving a vaccination center in London. (John Sibley/Reuters)

Why? Because the single biggest difference between these recovering countries and the rest of the world is immunity — both the kind acquired from prior infection and, going forward, the kind acquired from vaccination. As more dangerous variants take over, hard-hit countries with higher rates of vaccination are (mostly) withstanding the onslaught. Hard-hit countries with lower rates of vaccination are (mostly) not. This suggests that until vaccination has ramped up everywhere, the virus will keep spreading, evolving and threatening to dodge our defenses.

And that’s not just someone else’s problem. The more vaccines that rich countries buy up — and the slower that some of them vaccinate their own populations — the more likely it is that poorer, less protected countries will serve as breeding grounds for variants, prolonging the risk for everyone.

Consider the data. To date, more than 56 percent of Israel’s population has received at least one vaccine dose. No other major country comes close. All told, Israeli researchers now estimate that more than 90 percent of residents over 60 have some degree of immunity, through either vaccination or prior infection.

As a result, new hospitalizations among these older Israelis have fallen nearly 80 percent over the last two months — even as the more contagious and deadly U.K. variant, known as B.1.1.7, has superseded all other strains in the country. The fact that hospitalizations haven’t declined as much among younger residents only proves the point: Fewer of them have been vaccinated. That should change soon.

Meanwhile, Israel’s latest lockdown ended one month ago, and the economy fully reopened last week. At a similar interval after the country’s previous lockdown, the average number of people infected by one infectious individual was already at 1.1 and rising, indicating exponential spread. (Anything over 1.0 means an outbreak is growing.) Today it’s at 0.68.

A elderly woman receives a booster shot
A woman receiving a coronavirus vaccination in Netanya, Israel, in January. (Ronen Zvulun/Reuters)

Neither the U.S. nor the U.K. has vaccinated such a large share of its population. But they’re doing a lot better than most countries, and it’s showing. Nearly 38 percent of U.K. residents have received at least one dose so far, including more than 80 percent of those over 60. (The U.K. is delaying booster shots for up to 12 weeks in order to initiate vaccination in as many people as possible as quickly as possible.) On average, COVID-19 deaths among seniors in England fell by 63 percent between Feb. 19 and March 5, compared with 53 percent among nonseniors — a sign that vaccination is starting to push numbers down independent of other factors, such as the country’s recent lockdown.

At the same time, at least 73.7 million Americans have received one vaccine dose, or more than 22 percent of the population; more than two-thirds of seniors have initiated vaccination. Layer that atop America’s existing foundation of natural immunity — experts estimate that about 35 percent of the population has already been infected — and the virus starts to have a harder time finding new hosts. This largely explains why over the last two weeks U.S. cases have still fallen by 15 percent and hospitalizations have still fallen by 23 percent, even as B.1.1.7 is spreading rapidly and is expected to account for more than half of all U.S. infections before the end of the month — even as reopening accelerates.

Which isn’t to say the U.S. has vanquished its variants. In recent days, nationwide cases have plateaued around 55,000; while cases continue to fall in most states, they are starting to flatten or even creep up in much of the Northeast and Mid-Atlantic and parts of the Upper Midwest.

Michigan may be the most unsettling example. There, cases are up 84 percent, on average, over the last two weeks; hospitalizations are up 31 percent. Perhaps not coincidentally, the Great Lakes State is second only to Florida in the number of B.1.1.7 cases detected among residents — without the warm weather (yet) that makes outdoor gathering so much easier in America’s spring break capital.

A nurse
A nurse coordinates COVID-19 vaccinations at Second Ebenezer Church in Detroit. (Emily Elconin/Reuters)

Similarly, New York City’s seven-day average rate of positive test results has not dipped below 6 percent in months — the likely result, officials said this week, of a local variant that is accounting for a growing share of new cases in the city. Overall, new cases per capita in New York and New Jersey are at least double the national average right now, and the plateauing rates in nearby Rhode Island, Massachusetts and Connecticut are causing concern.

Ultimately, however, experts expect the downward pressure from America’s accelerating vaccination effort — which is starting to expand, ahead of schedule, beyond the initial priority groups even as it shields vulnerable seniors from hospitalization and death and protects frontline workers from infection and transmission — to temper and finally suppress most of the upward pressure attributed to variants. In short, the U.S. might see some leveling off during its final descent out of the pandemic. But with each passing day of vaccination — now averaging 2.5 million doses every 24 hours — a full-blown fourth wave looks less and less likely.

Sadly, that’s not the case elsewhere.

As B.1.1.7 spreads throughout the European Union, cases have shot up 52 percent over the last month. In many countries — Estonia, Hungary, Poland, Sweden, France, Italy, Austria, even Germany — the curve is sloping steeply upward. Yet none of these nations has managed to administer at least one dose to more than 15 percent of its population, and most of them are doing far worse, with Austria at 9.3 percent, Sweden at 8.3 percent, Germany at 8.2 percent, Italy at 8.2 percent, France at 8.2 percent, the EU as a whole at 8.1 percent and Poland at 7.9 percent.

On Thursday, Dr. Hans Kluge, the World Health Organization’s regional director for Europe, told reporters that Europe’s level of vaccination is too low to slow transmission. In Central Europe, the Balkans and the Baltic states, he added, new cases, hospitalizations and deaths are now among the highest in the world. The recent suspension of the AstraZeneca vaccine — and the hesitancy it might stir up even now that Europe’s drug regulator has deemed it safe and effective — won’t help matters.

Packages of AstraZeneca's COVID-19 vaccine
Supplies of COVID-19 vaccine at a facility in Cologne, Germany. (Thilo Schmuelgen/Reuters)

Most of the rest of the world trails even further behind. In Brazil, where, again, cases have risen more than 50 percent over the last month, just 5.1 percent of the population has received at least one vaccine dose. In India, where cases have climbed more than 110 percent, just 2.2 percent of the population has received one dose. Morocco is the only African country to have administered at least one shot to more than 5 percent of its population, and no country in Asia or Oceania has even approached that number.

Vaccination, of course, isn’t the only reason COVID-19 is hitting some places harder than others right now. But it is the main reason, along with natural immunity, why some places are unlikely to experience a true fourth wave of infection — and why even a fourth wave in other places may not be the last.

The contours of a new world split between vaccine haves and have-nots is already taking shape. For some, life as normal is on the horizon; for others, the crisis will continue, with all its disruptions and dangers. Meanwhile, the virus will continue to mutate as long as it has somewhere to spread.

By the end of May, the U.S. will have received about 500 million doses of vaccine — enough to fully immunize every adult in the country. All told, the White House has reserved more than 1.2 billion doses, enough to vaccinate the entire U.S. population twice over, and then some. Predictably, most wealthy countries have placed similar orders. Most developing countries have not. And so Europe doesn’t just owe itself a more efficient rollout. It owes the world, too — with a more equitable distribution of doses to follow. Until then, the waves will continue, and for most, the pandemic will not end.

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