the virus had taken its already formidable ability to evade immunity and pushed it to another level
By the middle of 2022, the virus that had already reshaped human life found yet another way to outpace the defenses built against it. The Omicron subvariant BA.5, spreading across 62 countries, carried mutations that allowed it to slip past prior immunity with unusual ease — a reminder that biological evolution does not pause for human exhaustion. Scientists like Eric Topol watched its advance with sober concern, not because death was surging in proportion to infection, but because the gap between what the virus could do and what medicine could answer was widening again.
- BA.5 has become the most immune-evasive version of COVID-19 yet, capable of reinfecting people whose bodies had already learned to fight earlier variants.
- Hospitalizations are climbing in Portugal, Israel, and across Europe, signaling that 'living with the virus' still carries a real and measurable human cost.
- Pandemic fatigue is undermining the most reliable tools available — masking, ventilation, distancing — precisely when a more transmissible wave demands their use.
- Only one in four Americans over 50 has received a fourth booster dose, despite CDC data showing it reduces mortality by 99 percent compared to three doses.
- Vaccine developers are racing to build BA.1-targeted boosters that may already be obsolete by the time they reach arms, with a BA.5-specific version still months away.
- Scientists warn that more disruptive variants — from within Omicron or beyond — are likely coming, and the infrastructure to respond is moving slower than the threat.
By late June 2022, virologist Eric Topol of the Scripps Translational Science Institute offered a stark assessment: BA.5, the newest Omicron subvariant, was the worst version of COVID-19 the world had yet encountered. Already detected in 62 countries, it was driving fresh waves of infection with a capacity for immune evasion that exceeded anything before it.
What set BA.5 apart was not just a mutated spike protein — the familiar target of vaccines and antibodies — but changes extending deeper into the viral structure, giving it a growth advantage over earlier subvariants. Laboratory studies in Syrian hamsters showed BA.5 and its close relative BA.4 spreading more efficiently through lung tissue and causing more severe disease than prior Omicron strains. The practical result was a virus that could reinfect people whose immunity had drifted too far from what BA.5 now presented.
The consequences were already visible. Portugal, where BA.5 first rose to prominence outside South Africa, saw hospitalizations climb as the variant became dominant. Europe and Israel followed similar trajectories. Mortality had not surged proportionally, but the numbers were rising in both hemispheres at once, and the risk of reinfection had grown substantially.
Responding was both urgent and complicated. High-quality masks, ventilation, and distancing remained effective, but pandemic fatigue had eroded public willingness to use them. Booster doses — particularly a fourth shot for those over 50 — offered meaningful protection; the CDC documented a 99 percent reduction in mortality compared to three doses. Yet only one in four eligible Americans had received it.
The deeper difficulty was one of timing. Boosters being developed to target BA.1 would likely arrive after BA.5 had already become globally dominant, and a BA.5-specific booster was still months away — a delay Topol called unacceptable. With no guarantee that any targeted booster would hold against the next emerging variant, the pandemic's trajectory remained clear: the virus was evolving faster than the systems designed to contain it.
By late June 2022, a new subvariant of Omicron was spreading faster than anything public health officials had seen before. Eric Topol, the scientist who directs the Scripps Translational Science Institute in California, called it plainly: the worst version of the virus yet. The subvariant, known as BA.5, had already been detected in 62 countries and was driving a fresh wave of COVID-19 infections across the globe.
What made BA.5 different was its ability to slip past the body's defenses. The spike protein—the part of the virus that the immune system learns to recognize—had mutated in ways that made it harder for antibodies from previous infections or vaccinations to catch it. But the changes went deeper than that. The mutations extended into other parts of the viral structure, giving BA.5 a growth advantage over earlier Omicron subvariants like BA.2. In laboratory studies using Syrian hamsters, BA.5 and its close relative BA.4 caused more severe disease and spread more efficiently through lung tissue than what had come before. Topol noted the troubling implication: the virus had taken its already formidable ability to evade immunity and pushed it to another level, which meant it could infect more people, more easily.
The real-world consequences were already visible. Portugal, where BA.5 first gained prominence outside South Africa, saw hospitalizations climb noticeably as the variant became dominant. The same pattern was emerging across Europe and in Israel, though the picture was complicated by the fact that BA.5's rise often coincided with BA.2's decline, masking the true scale of the new wave. Still, the numbers were climbing in both hemispheres simultaneously, and the risk of reinfection had grown substantially. People who had been infected months earlier found themselves vulnerable again because their immune systems had drifted too far from what BA.5 presented.
The question of how to respond was urgent and uncertain. Masks—the high-quality N95 and KN95 kind—along with social distancing, ventilation, and air filtration would help, but pandemic fatigue had worn down public willingness to adopt these measures. Booster shots offered real protection, especially for people over 50. The CDC had documented that a fourth dose reduced mortality by 99 percent compared to three doses, a 14-fold improvement. Yet only one in four Americans over 50 had actually received that fourth shot.
The deeper problem was timing. Vaccine developers were working on boosters specifically designed to target BA.1, but by the time those would be ready, BA.5 would likely be the dominant variant everywhere. Waiting for a BA.5-specific booster would take months—longer than the original vaccine development in 2020, which had taken ten months. The approval and manufacturing process for variant-specific boosters had proven painfully slow, a delay Topol called unacceptable given the stakes. And there was no guarantee that a booster aimed at one subvariant would work well against the next one that emerged. More problematic variants were coming, he warned, whether from within the Omicron family or from some entirely new lineage. The pandemic was not over; it was simply evolving faster than the tools to fight it.
Notable Quotes
BA.5 is the worst version of the virus we've seen— Eric Topol, Scripps Translational Science Institute
The virus has taken its already formidable ability to evade immunity and pushed it to another level, resulting in greater transmissibility— Eric Topol
The Hearth Conversation Another angle on the story
Why does Topol call BA.5 the worst version we've seen? Isn't that a strong claim?
He's not talking about severity in the traditional sense—death rates haven't spiked. He means the virus itself has become more evasive and transmissible. It's slipping past immunity in ways previous variants couldn't. That's what makes it dangerous.
But if hospitalizations aren't surging proportionally to cases, why the alarm?
Because the alarm is about what comes next. More infections mean more hospitalizations in absolute numbers, even if the rate is lower. And we don't know yet if BA.5 might become more severe. The hamster studies hint it could be.
What about the boosters? Aren't they still protective?
They are, especially for older people. A fourth dose cuts mortality dramatically. But most people aren't getting them. And the boosters being rolled out now target BA.1, not BA.5. By the time a BA.5-specific booster exists, the virus will have moved on again.
So we're always chasing the variant that's already dominant?
Exactly. The vaccine development process takes months. The virus evolves in weeks. That gap is the real problem.
Is there anything that actually works right now?
Masks, distance, ventilation—the basics. They work. But people are exhausted. The pandemic has worn down the will to do these things, even when they're necessary.