The BA.5 Covid variant is causing US cases to rise - should you be worried? All you need to know

How worried should I be about BA.5?

Covid-19 cases and hospitalizations are rising in the US as BA.5 - the newest subvariant of Omicron - becomes dominant in the country, raising concerns that the immune-evasive variant will lead to another wave of illness and death.

The Biden administration announced a plan to address the BA.5 wave that largely relies on the same tools of vaccines, treatments and tests.

Yet the newest challenge hits a nation whose leadership has largely moved on from Covid. Few policies on precautions are in place, federal funding is running out for vaccines, treatments, tests and other mitigations, and there is little public discussion of the prevalence of Covid and the continuing importance of curtailing its spread.

Against this backdrop, questions about BA.5 and other new variants abound: are they more transmissible or severe? Do the same precautions work against a rapidly evolving virus? Our experts tackled these questions and more.

Are cases rising everywhere in the US?

Pretty much, yes. Over the past two weeks, cases have increased in 38 US states, and hospitalizations have increased in 43 states. Some of the greatest case increases are among states with the lowest vaccination rates, including Louisiana, Wyoming and Arkansas - despite widespread infection in previous waves, pointing to the greater protection offered by vaccines.

According to official case numbers, the US has been in a plateau for several weeks, but the total case count - in addition to being vastly under-reported - cloaked the concurrent fall of BA.2 subvariants and the rapid rise of BA.5.

The ascension of the new, more immune-evasive variant shows no signs of slowing. The US is now seeing the likely beginning of a surge, with more than 120,000 new cases confirmed each day and hospitalizations rising by 12% last week from the week before.

"The best data we have right now - which is surely not ideal, it's lagging - is hospitalizations," said Michael Osterholm, an epidemiologist and director of the Center for Infectious Disease Research and Policy at the University of Minnesota. A rise in hospitalizations can indicate factors like increasing cases or worsening severity.

"It's going to take us probably another couple of weeks really to understand what's [happening] with BA.5, but it could be substantial," Osterholm said.

"It seems like it's going to move through the country. The scary possibility is that it moves through a really sustained way," said Vanessa Lamers, who leads the vaccination program at the non-profit Public Health Foundation.

"That is going to depend on how much preexisting immunity we actually have, what kind of behaviors and mitigation strategies there are in place both in governments and communities, and how much we've prepared for another wave."

But she is particularly concerned about BA.5's rapid rise. It has "already surpassed the peak of the BA.2 variants and doesn't really seem to be plateauing," she said. "I don't think anyone likes seeing that curve continue to go up and up."

If I'm vaccinated, boosted, or have recovered from Covid already, am I safe?

That depends on how you define "safe".

If you have gotten a shot or recovered from a case recently, you may not be protected against infection, but you are less likely to develop severe illness.

BA.5 seems to be very adept at evading prior immunity - even among those who had BA.1. Even if reinfections are less severe for most people, the more cases there are in a population, the higher the chances more people will be hospitalized or die from breakthrough infections.

"Clearly we're seeing many breakthrough cases, including some that are severely ill," Osterholm said. It is also possible to develop long Covid even after a mild or asymptomatic case.

Every new infection offers the virus an opportunity to evolve and that means newer variants can become better at evading protection against infection.

"It is challenging the very basis upon which we have tried to build, in terms of immune protection," Osterholm said.

Much of the American public already has some level of protection, from vaccination, recovery, or both.

But immunity from coronaviruses tends to wane more than immunity to other viruses, Lamers said.

She thinks of immunity like water in a cup. "Every little bit that you can fill up that water glass to the top - that is going to give you more protection."

Those who recovered from a previous case but haven't been vaccinated have a little water in their cup, and those who have been vaccinated and boosted have much more. But the water also evaporates over time and needs to be refilled regularly.

"For people who are fully vaccinated, they got a booster, they got another booster - maybe in between one of those vaccines, they got an infection - they probably have a really full cup," Lamers said. "The problem is that after about six to eight months, if your immune system has not been primed, the cup has not had a little bit put in there - then your immunity against it is going down."

How common is it to be reinfected?

It's hard to tell how many of these cases are being driven by new infections or reinfections, particularly because the US doesn't track cases as much as it used to.

"There are no systematically collected data that really address this," Osterholm said. "So this is an area where we do need to count all the cases so we have that kind of information."

But from the genomic surveillance that does exist, some of the new cases are "clearly" emerging among people who had BA.1, he said.

Boosters can reduce the chances of getting infected and they are very good at preventing severe illness and death.

Is BA.5 more transmissible than previous variants?

"At this point, I don't think we can tell," Osterholm said.

It's hard to untangle transmissibility from other factors - like how good the variant is at overcoming immunity.

Changing behavior probably accounts for some of BA.5's spread. The relative lack of precautions in the US and the difficulty understanding how many cases there are and how prevalent the virus is, means that more people may be at risk of getting sick than in previous waves.

Is it as severe as other variants?

In animal studies, BA.5 appears to be more severe. But in real life, where much of the population has some immune protection, it may not be clinically significant - especially given the continued protection the vaccines offer against severe illness.

"All the data we're seeing right now supports that particularly four doses of vaccine does provide substantial protection from serious illness, hospitalizations and deaths," Osterholm said.

"Statistically, you're going to have a lower risk of having severe illness" if you're vaccinated, he said. "That's a really key message."

But communities with low vaccination rates may be harder hit.

How have other countries fared?

In Portugal, cases, hospitalizations, and deaths rose significantly. But in South Africa, cases rose somewhat while hospitalizations and deaths stayed relatively low.

"The question is, what is it going to do here?" Osterholm asked. "It's still unknown right now."

There are differences between these populations - Portugal is highly vaccinated, while South Africa is younger and may have had additional protection from their outbreak of the Beta variant, which did less damage in the US.

Another new variant, BA.2.75, that is rising in some countries may also complicate predictions of what happens next.

What is the best precaution against BA.4/5?

"The same kinds of protections that worked for Omicron BA.1 are going to work for BA.5," Lamers said.

That includes being up to date on vaccines, especially boosters; wearing a high-quality, well-fitting mask, especially in indoor settings; widespread testing and treatment options and ventilation and air filtration.

Measures like these "can do a lot for your risk of transmission", Osterholm said.

"It still has to be a multilayer strategy," Lamers said. "It's not magic; it's still a virus."