BA.2 COVID variant sweeping Asia and Europe is the most unpredictable yet

After spreading across Asia and Europe, the BA.2 subvariant of the new coronavirus is now dominant in the United States, according to the United States Centers for Disease Control and Prevention.

Right now, COVID cases in the United States are at a six-month low. But what will happen next in the United States and neighboring countries is difficult to predict. Looking to Europe for clues isn’t very helpful because, on that continent, BA.2 behaved…unpredictably. Indeed, the unpredictability might be exactly what Americans — and everyone else — should expect as the pandemic enters its 28th month.

A patchwork of public health rules, varying vaccination rates and differing levels of natural immunity to past infections mean no two countries are the same. But even these differences do not fully explain the unequal impact of BA.2.

“The bottom line is that it’s not predictable what BA.2 will do,” said John Swartzberg, professor emeritus of infectious diseases and vaccinology at the School of Public Health at the University of California, Berkeley, at the Daily Beast.

Amidst this confusion, at least one thing remains true, however. As unstable as BA.2 is when it comes to countries and populations, you can still protect yourself by getting vaccinated.

Usually there is a pattern with new COVID lineages. A slight increase in positive tests in clinics, hospitals and sewage samples correlates with a proportional increase in symptomatic infections.

But when it comes to BA.2, “something different seems to be happening,” Peter Hotez, a vaccine development expert at Baylor College, told The Daily Beast. “BA.2 is increasing everywhere in terms of the percentage of viruses isolated” in testing, Hotez explained, “yet this translates to many different scenarios in terms of increased cases.”

“I can’t say for sure that this can be attributed to their vaccine policies or their vaccine policy alone.”

BA.2 is a highly mutated cousin of the previously dominant Omicron subvariant BA.1, the last major variant – “lineage” is the scientific term – of the SARS-CoV-2 virus. Changes to the spike protein, which helps the virus grab and infect our cells, make BA.1 and BA.2 extremely transmissible.

BA.1, which first emerged last fall and quickly caused record infections across much of the world, was the most contagious respiratory virus many virologists had ever seen, until BA .2 appears a few weeks after its older cousin. BA.2 could be up to 80% more transmissible than BA.1, Swartzberg said.

A health worker takes a swab sample from a man to test him for COVID-19 at a testing site along a street in Beijing on March 15, 2022.

Jade Gao/AFP via Getty

This is why BA.2 eventually supplanted BA.1 and became the dominant sub-lineage in an ever-increasing number of countries. This happened first in China, which for more than two years has managed to avoid major COVID outbreaks through a combination of travel restrictions, business closures, careful contact tracing and safety rules. strict quarantine.

BA.2 blew up China’s so-called “zero-COVID” strategy, causing cases to spike in Hong Kong and then neighboring Shenzen and then Shanghai. Authorities have locked down each city in turn, but have still failed to stop the underline’s march across the country.

Europe was next. Health officials in the Americas nervously watched BA.2 become dominant in one European country after another. After all, Europe tends to catch a particular lineage or sublineage of coronavirus a month or six weeks before the United States and its neighbors.

But BA.2 did not send clear signals. The first confusing data point was actually not in Europe, but in Africa. Oddly, BA.2 was a virtual no-show in South Africa. This country recorded a sharp increase in BA.1 cases in December, then … nothing. A steady decline in cases even as BA.2 ravaged other major wealthy countries.

Some European countries also escaped significant damage from BA.2. Others are shaken.

The UK and France caught BA.1 in December and January. Both countries reported record numbers of cases which, thanks to vaccines, fortunately did not result in record hospitalizations and deaths. Austria, on the other hand, got confused in BA.1 before taking a huge struck with BA.2.

The UK reported a weekly average of 183,000 daily new cases in early January. Three weeks later, France had a staggering weekly average of 354,000 new daily cases. The worst day in the UK for BA.1 deaths was February 2, when authorities reported 535 COVID deaths. On BA.1’s worst day in France, February 8, 691 people died from COVID.

Comparing the two countries is natural. Not only are they neighbors, but they also have about the same number of people – around 67 million. Both managed to fully vaccinate about three quarters of their population. Both have lifted all major national COVID-related restrictions.

It makes sense that BA.2 affects France and the UK equally. And there, at least, the subline made sense. The BA.2 wave that crossed the UK and France from February was relatively minor compared to the BA.1 wave, in both countries.

New daily BA.2 cases in France appear to be stabilizing at a weekly average of 126,000 infections. The weekly average of new daily cases in the UK peaked at 125,000 on March 21. Deaths tend to delay cases by a few weeks, so it’s unclear how deadly BA.2 will be in either country, but so far the worst daily death toll is much lower than it was for BA.1.

Now consider Austria. With just 8.9 million people, it’s smaller than the UK and France. But he is just as well vaccinated – and even came close to having a national vaccination mandate before canceling the planned mandate in early March, days before it came into effect. Austria, like most countries in Europe, has ended national restrictions on business and travel.

But unlike the UK and France, Austria grabbed BA.2 worse than BA.1. Daily rates of new BA.1 cases ballooned to a weekly average of 34,000 and stayed there for a month and a half. Then BA.2 arrived in early March and, without much respite from BA.1, added an additional 10,000 new daily cases on top of the existing weekly average.

“I don’t see a consistent common thread between countries.”

Apart from a small drop in mid-March, the daily death rate has been increasing every week since January in Austria. BA.2 causes 40 deaths per day, day after day on average.

It is difficult to determine which policies make a difference – assuming that differences in public health strategy matter at all against a virus as contagious as BA.2. Yes, Austria almost had a vaccine mandate, but it didn’t go into effect. And it is very difficult to say what the impact of the proposed mandate was or would have been.

“Even if no additional people were vaccinated after the introduction of a mandate, that does not mean that it did not “work”, because the purpose of the mandate may have simply been to ensure that the only people you meet when you’re at a restaurant or concert are vaccinated,” Maxwell Smith, a bioethicist at the University of Western Ontario, told The Daily Beast.

A screen shows the number of new COVID-19 infections nationwide at a subway station on March 17, 2022 in Seoul, South Korea.

Chung Sung-Jun/Getty

“In this case, the ‘functional’ vaccination mandate would mean reducing levels of virus transmission in the settings to which it applies,” Smith added. “Or, in the case of preserving critical infrastructure, it would mean something like fewer serious illnesses or hospitalizations among those to whom the mandate applies.”

There are many ways Austria’s vaccination mandate may have improved outcomes for millions of Austrians at risk of catching COVID. But that did not prevent Austria as a whole from suffering more from BA.2 than other neighboring countries.

“Many factors may have led to the number of cases we are seeing in both Austria and its neighboring countries, so I cannot say with certainty that this can be attributed to their vaccination policies or to the vaccination policy alone. says Smith.

Experts are unable to explain what other factors might be at work. If neighboring countries have vaccinated roughly the same percentage of their population and have also reopened their borders, businesses and schools, allowing some level of natural immunity against past infections, then they should also be prepared for a new viral line.

Obviously, they are not. “I don’t see a consistent thread between countries,” Swartzberg said.

There are serious implications for the rest of the world as it prepares for BA.2. Even high vaccine uptake and lingering natural immunity might not spare you a big bump of infections. Similarly, BA.2 could simply bypass a country for reasons no one fully understands, as was the case with South Africa.

But the experiences of whole countries are not the experiences of individuals. Yes, BA.2 can have unpredictable effects on populations. But the science is clear on how people can reduce their personal risk. Prioritize well-ventilated interior spaces. Wear an N95 mask when local case rates are high.

Above all, get vaccinated and boost.

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