(CNN) – Nearly two-and-a-half years since the coronavirus pandemic began, the most infectious and transmissible variant yet has arrived.
Repeated Covid-19 waves have left millions of people dead, with only vaccines helping to blunt the toll. Now the virus is spreading again — evolving, escaping immunity and driving an uptick in cases and hospitalizations. The latest version of its shape-shifting, BA.5, is a clear sign that the pandemic is far from over.
The newest offshoot of Omicron, along with a closely related variant, BA.4, are fueling a global surge in cases — 30% over the past fortnight, according to the World Health Organization (WHO).
In Europe, the Omicron subvariants are powering a spike in cases of about 25%, though Dr. Michael Ryan, the executive director of WHO’s Health Emergencies Program, has said that number may actually be higher, given the “almost collapse in testing.” BA.5 is on the march in China, ratcheting anxieties that major cities there may soon re-enforce strict lockdown measures that were only recently lifted. And the same variant has become the dominant strain in the United States, where it accounted for 65% of new infections last week, according to the Centers for Disease Control and Prevention (CDC).
“We have been watching this virus evolve rapidly. We’ve been planning and preparing for this moment. And the message that I want to get across to the American people is this: BA.5 is something we’re closely monitoring, and most importantly, we know how to manage it,” said Dr. Ashish Jha, the White House’s Covid-19 response coordinator, in a news briefing on Tuesday.
On the same day, WHO’s Emergency Committee said Covid-19 remained a Public Health Emergency of International Concern — its highest level of alert, first declared on January 20, 2020 — amid rising cases, ongoing viral mutation and increasing pressure on already overstretched health systems. In a statement, the committee, which is made up of independent experts, highlighted challenges to the ongoing global Covid-19 response, including a drop-off in testing and spotty genome sequencing, raising the question of just how accurately any nation might reasonably be able to monitor BA.5.
Official data dramatically undercount the true number of infections in the US, epidemiologists say, leaving the nation with a critical blind spot as the most transmissible coronavirus variant yet takes hold. Some experts think there could be as many as 1 million new infections every day in the broader US population — 10 times higher than the official count.
As for how to manage the new wave, Jha urged Americans aged 50 and older to get second booster shots. Adults who are up to date with vaccinations are less likely to be hospitalized than those who are unvaccinated. But only about one in four adults in the US over 50 have gotten their recommended second boosters, data collected by the CDC show.
US health officials are urgently working on a plan to allow second Covid-19 boosters for all adults, a senior White House official confirmed to CNN on Monday, amid fears that younger adults’ immunity may be waning as Covid-19 cases rise with the dominance of BA.5.
What makes BA.5 different? Eric Topol, a cardiologist and professor of molecular medicine at Scripps Research, has called BA.5 “the worst version of the virus we’ve seen.” He explained in a recent newsletter: “It takes immune escape, already extensive, to the next level, and, as a function of that, enhanced transmissibility,” well beyond earlier versions of Omicron.
In other words, BA.5 can easily evade immunity from previous infections and vaccines, increasing the risk of reinfection. Though the variant does not appear to lead to more severe illness, in an interview with CNN on Monday, Topol said that given the extent of BA.5’s immune evasion, he expects to see an escalation in hospitalizations, as we’ve seen in Europe and elsewhere that the variant has taken root. “One good thing is it doesn’t appear to be accompanied by the ICU admissions and the deaths as previous variants, but this is definitely concerning,” he added.
Public health experts in the US may take some solace from the trajectory of the variant in Europe. WHO’s Ryan said last week that while many European countries are experiencing a jump in hospitalizations, “what we’re not seeing is an increase in intensive care unit admissions, so the vaccines are very much still working and it is those gaps in immunity that are causing the problem.”
But still, steep reductions in Covid-19 surveillance worldwide are hindering epidemiologists’ efforts as they race to trace the virus’ evolution.
“Sub-variants of Omicron, like BA.4 and BA.5, continue to drive waves of cases, hospitalization and death around the world,” WHO Director-General Tedros Adhanom Ghebreyesus said in a media briefing on Tuesday. “Surveillance has reduced significantly — including testing and sequencing — making it increasingly difficult to assess the impact of variants on transmission, disease characteristics, and the effectiveness of counter-measures.”
“New waves of the virus demonstrate again that the Covid-19 [pandemic] is nowhere near over,” he added.