How is the Omicron BA.5 COVID-19 variant different from other strains? Symptoms, reinfection and severity

According to estimates released Tuesday by the Centers for Disease Control and Prevention (CDC), Omicron’s fast-spreading subvariant BA.5 and its close relative BA.4 now account for about 95% of all COVID-19 cases in the United States.

Strains boost rate of new COVID-19 cases this month – President Biden among them. Hospitalizations in some areas were the worst days of last year’s Delta wave, particularly among Americans age 70 and older.

CDC officials said they are now studying the current wave, with initial results due late next month on how it affects issues such as vaccine effectiveness. And data from other countries that survived the wave of events of BA.5 and its close relative BA.4 can provide clues about what’s to come.

However, the nature of the pandemic has changed in important ways, and there are now vast populations of people who are either previously infected, protected by vaccines, or both. This is an attempt to study the virus.

Fever and sore throat cause loss of taste and smell

Data from research in the UK, as well as the country’s ongoing COVID-19 survey, show that there is a share of ill residents there. Loss of taste and smell are once characteristic symptoms significantly decreased compared to before the pandemic.

This was a shift first noticed by scientists around the world during the winter wave of Omicron BA.1 subvariant infections. Instead, flu-like symptoms of COVID-19 are now being reported.

The percentage of people who tested positive who reported abdominal pain, fever, sore throat and muscle pain in June 2022, compared to May 2022, reported by June 24.

However, it is difficult to say how much of this shift is due to changes in the virus. The researchers speculate that immunity from previous infections may also influence the overall symptoms seen during recent Omicron waves.

Re-infections occur

Re-infection rates have increased since the Omicron variant arrived in the UK and other countries over the winter.

Federal researchers estimate that the BA.4 and BA.5 mutations place them farthest from the original strain of the 2020 virus and closer to the Beta variant first seen in May 2020 than its Omicron cousin BA.1.

According to data from a series, individuals who survived a COVID-19 infection prior to the Omicron variant were only 15% protected against symptomatic re-infection by BA.4 or BA.5. If the previous infection was from another Omicron subvariant, this estimate rises to 76%.

Here in Washington state, for example, health officials have noted a steady increase in reinfections over the past few months, but they acknowledge that factors such as at-home testing may be undercounting.

“What’s the closest parallel to what we’re seeing in the US? The UK is the closest, but the UK itself is so far from what we’re seeing here in the US,” said Venky Soundarajan, chief scientist at the research firm. A link.

Soundaarajan recently teamed up with scientists from the National Institutes of Health to publish the study in PNAS Nexus, identifying the variants’ “uniqueness” compared to variants previously common in a particular region of the world. The authors found that this new metric can predict future increases in variants in different parts of the world, based on which variants are prevalent in those regions.

Soundararajan cited the large gap in new COVID-19 cases between the two countries in March, when the UK reported a sharp increase in BA.2 infections while cases in the US were slowing.

Their data suggest that while the significant growth advantage of BA.5 may have contributed to the increase in cases, the “wall of immunity” built during the winter surge will not reach the same record highs as the current surge.

“The BA.5 Omicron is not that different from what we’ve seen in the US, especially the BA.2.12.1, which is the most recent type. And the BA.1 continues to provide very high exposure levels for us. Suspect will continue to play throughout the summer,” – added Soundarajan.

Severe disease rates remain lower than in previous waves

Although the rate of COVID-19 hospitalizations has accelerated across the country, measures of some of the worst outcomes of the disease remain much lower than in some previous waves in the pandemic.

A relatively small fraction of hospital intensive care unit beds across the country are occupied by COVID-19 patients. The rate of new COVID-19 deaths remains worse than this time last year, averaging an “unacceptable” rate of more than 300 deaths per day. However, even among vulnerable groups such as nursing home residents, the daily death toll from COVID-19 remains a fraction of previous waves.

Federal health authorities have fueled this “separation” with vaccinations, particularly booster doses, as well as widespread use of COVID-19 treatments such as Pfizer’s Paxlovid pills.

A study published last week in the New England Journal of Medicine suggests that currently available COVID-19 drugs work against the BA.4 and BA.5 subvariants.

Data from South Africa’s wave of cases earlier this year for the two subvariants show that compared with Omicron’s original BA.1 subvariant, they carry a similar risk of hospitalization and severe illness from COVID-19.

However, early studies from countries such as Denmark and Portugal suggest that BA.2 may have a higher risk of hospitalization compared to BA.2. Early laboratory tests with subvariants, such as those recently released by scientists in Australia, suggest that BA.5 may pose a greater risk due to its ability to infect lung tissue.

Home tests may be more effective in detecting BA.5

During the first wave of Omicron BA.1 subvariant infections back in DecemberFederal health officials have acknowledged that some rapid at-home tests have lower sensitivity for detecting infections than earlier options, according to preliminary data.

“We’ve seen antigen tests drop in sensitivity in the Omicron era. That’s been posted on the FDA website for months. And the data just kept piling up its insensitivity,” Food and Drug Administration official Tim Stenzel said at a town hall last month about the COVID-19 test. reported by the manufacturers.

However, prior to a recent webinar with COVID-19 testing labs, Stenzel said he had seen early data suggesting that the regulator may have changed with BA.5, meaning home tests could detect it. subvariant.

The regulator is working with the National Institutes of Health’s RADx program at Emory University and the Georgia Institute of Technology to study the options’ impact on tests.

“There are some reports that may be less low positive. And some of the preliminary data suggest that they may be active. So we could see improved antigen test performance with BA.5,” Stenzel said last week.

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