The rapidly spreading BA.5 variant of Omicron and its close relative BA.4 make up about 95% of COVID-19 cases in the United States, according to estimates published Tuesday by the Centers for Disease Control and Prevention (CDC).
Tensions have accelerated the pace of new COVID-19 cases this month – President Biden. Hospitalizations in some areas have now passed the worst days of the variable delta wave last year, especially among Americans 70 and older.
CDC officials say they are now studying the current wave, with early results on how variables affect issues like vaccine efficacy due later next month. Data from other countries that have already escaped a wave of cases from BA.5 and its close relative, BA.4, could provide clues as to what will happen.
However, the nature of the pandemic has changed in important ways, and there is now a wide range of people with previous infections, protection from vaccines, or both. These are faltering attempts to study the virus.
Fever and sore throat outweigh loss of taste and smell
Data from studies in the UK, as well as the ongoing COVID-19 survey in the country, indicate that the proportion of the sick population there who reportsIt has decreased significantly since earlier in the epidemic.
This was a shift first observed by scientists worldwide during the Omicron BA.1 sub-wave of infection during the winter. Instead, COVID-19 flu-like symptoms are now more commonly reported.
As of June 24, the country’s Office for National Statistics reported: “The proportion of people who tested positive for abdominal pain, fever, sore throat and muscle pain increased in June 2022 compared to May 2022.”
But it is difficult to quantify this shift due to the change in the virus itself. The scientists hypothesized that immunity from previous infections could also play a role in influencing what appear to be common symptoms seen during recent omicron waves.
High infection rates
The rate of re-infection has increased in the UK and other countries since the arrival of the Omicron variant during the winter.
Federal researchers estimated that the BA.4 and BA.5 mutations place them among the furthest from the original strain of the virus in 2020, and even closer to the Beta variant first seen in May 2020 than to Omicron’s cousin BA.1.
Data from Qatar indicate that subjects who survive COVID-19 infection before the Omicron variant have only 15% protection from symptomatic recurrence of infection by BA.4 or BA.5. If the previous infection was from another Omicron variant, this estimate rises to 76%.
Health authorities here, for example, in Washington state, have also noticed a steady increase in cases again over the past few months, although they acknowledge that this may be underestimated by factors such as home testing.
said Venky Soundararajan, chief scientific officer of research firm Neverness.
Soundararajan recently worked with National Institutes of Health scientists to publish research in the PNAS Nexus to determine the “characteristics” of variants, compared to those previously spread to a particular region of the world. The authors found that this new measure could predict differences in future increases in variables in different parts of the world, depending on which variables were previously prevalent in those regions.
Soundararajan cited the wide gap in new COVID-19 cases during March between the two countries, when the UK reported a sharp increase in BA.2 infections at a time when cases in the US were slowing significantly.
Their scale indicates that while BA.5’s large growth advantage will fuel an increase in cases, the “immune wall” built during the winter wave indicates that the current wave will not reach the same record heights.
“The BA.5 Omicron does not differ significantly in the United States, from what we saw, particularly with BA.2.12.1 which was the most recent subtype in circulation. BA.1 continues to deliver a very high level of exposure that we suspect will continue through the summer Soundararajan added.
Severe disease rates are still lower than in previous waves
Even as the pace of hospitalizations accelerates across the country, measurements of some of the disease’s worst outcomes are still much lower than during some previous waves in the pandemic.
COVID-19 patients accommodate only a relatively small percentage of hospital intensive care unit beds across the country. The pace of new COVID-19 deaths is still worse than it was at this time last year, with an “unacceptable” average of more than 300 deaths per day. But, even among the most vulnerable such as residents of nursing homes, the daily death toll from COVID-19 is still a small part of some previous waves.
Federal health authorities have considered this “chunch” even the protections offered by vaccination, especially the extra booster doses, as well as the broader use of COVID-19 treatments such as Pfizer’s Paxlovid pills.
A study published last week in the New England Journal of Medicine reports that currently available COVID-19 drugs will work against the BA.4 and BA.5 sub variants.
Data from South Africa’s wave of cases of the two subvariants earlier this year indicate that they pose a similar risk of hospitalization and severe disease with COVID-19 compared to the original BA.1 variant from Omicron.
However, early research from countries such as Denmark and Portugal now indicates that BA.5 may pose a greater risk of hospitalization compared to BA.2. Early lab tests with the alternative, such as those released recently by scientists in Australia, suggest that BA.5 may pose a greater risk thanks to its ability to infect lung tissue.
Home tests may be more effective in detecting BA.5
During the first infection wave of Omicron BA.1federal health officials acknowledged that early data suggests that some rapid at-home tests appear to be less sensitive in detecting infection than previous variants.
“We saw, early in the Omicron era, that it seemed like antigen tests were seeing a decrease in sensitivity. That was posted on the FDA website months ago. And the data kept accumulating that it’s not sensitive,” FDA’s Tim Stenzel said in a statement. Town hall last month with COVID-19 test manufacturers.
However, in a recent webinar with COVID-19 testing labs, Stenzel said the regulator had seen early – if still inconclusive – suggesting that it might have changed with BA.5, meaning that home tests are more likely to detect this sub variable.
The regulator is working with the RADx program of the National Institutes of Health at Emory University and the Georgia Institute of Technology to study the impact of variables on tests.
“There are some reports that there may be fewer low positives,” Stenzel said last week. “And some preliminary data suggests that might be the case. So we can see an improvement in antigen testing performance with BA.5.”