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Covid-19 levels have been rising in the United States for weeks as new variants cause what has become an annual summer surge.
Covid-19 surveillance has been significantly reduced since the US public health emergency ended more than a year ago – individual cases are no longer counted and serious outcomes are based on representative samples of the population – but available data shows a steady upward trend.
Infections are likely increasing in at least 38 states, according to data from the U.S. Centers for Disease Control and Prevention. Wastewater monitoring suggests virus activity is still relatively low, but hospitalizations and deaths are also rising.
Covid-19 levels are particularly high in the West, where viral levels have returned to what they were in February, and in the South, according to the CDC.
“The virus tends to replicate well and stay alive in a warm, humid environment. That’s consistent with what we’re seeing,” said Dr. Robert Hopkins, medical director of the National Foundation for Infectious Diseases, a nonprofit public health organization. “The South and West are currently experiencing severe heat. »
The summer surge has become a familiar seasonal phenomenon, but experts warn that the coronavirus can still be quite unpredictable.
“I think it’s still a little early to say what the trend is,” Hopkins said. “A lot of the population has been exposed to the virus, the peaks have been a little lower and we have tended to see a summer increase as well as a winter increase. But I think it’s still a little early to say if this trend will continue, if the disease will become a disease that occurs all year round or if it will remain at a particular period. »
Data from WastewaterSCAN, a national wastewater monitoring network based at Stanford University in partnership with Emory University, suggest that this summer surge began weeks earlier than last summer’s and reached levels similar to last summer’s peak.
“Whether this will be the peak level for this surge remains to be seen,” said Dr. Marlene Wolfe, assistant professor of environmental health at Emory and director of the WastewaterSCAN program.
“We are still trying to understand what the potential seasonality of Covid is and also what are the impacts of the new variants that could appear and which cause these surges that we observe more regularly, more frequently than for the flu and RSV,” he said. -she declared.
In recent months, the JN.1 variant of the virus, at the origin of this winter’s wave of contaminations, has been replaced by new variants. These variants, called FLiRT (an acronym for the location of amino acid mutations that the virus has detected), have changes in some places that help them evade the body’s immune response and in others that make it more transmissible. Two of them, KP.3 and KP.2, now account for more than half of new Covid infections in the United States, according to CDC data.
Due to manufacturing delays, experts must make predictions now if they want a new vaccine for the fall.
Earlier this month, the FDA approved a plan to update Covid-19 vaccines to be more effective against the JN.1 lineage of the coronavirus. But the agency later updated its own recommendation. Vaccine makers were advised to target the KP.2 strain if possible, in part because of the “recent surge in cases.”
“JN.1 has continued to evolve and it is somewhat difficult to choose the specific strain to use,” Dr. Jerry Weir, director of the Division of Viral Products in the Office of Vaccine Research and Review at the FDA Center . for Biologics Evaluation and Research, reported to an independent advisory committee prior to initial recommendation.
The new vaccines, some of which will target KP.2, are expected to be available between mid-August and late September. This is sufficient time to provide protection during the winter respiratory virus season, but likely after this summer’s wave has subsided.
On Thursday, the CDC recommended that everyone aged 6 months and older receive an updated Covid-19 vaccine for the 2024-25 season. This recommendation echoes the vote of this agency’s independent advisory committee.
“It makes sense to do this vaccine at the same time as you’re expecting flu and RSV, because you just want to reduce the overall incidence of disease,” Dr. Marcus Plescia, chief medical officer of the Association of State and Territorial Health. Officials told CNN.
Protection from Covid-19 vaccines is waning, and the timing of the injection prioritizes maximum protection when there have typically been higher, more sustained spikes, Plescia said. Unlike influenza and RSV, Covid-19 circulates constantly; it offers no respite.
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“You never get a break,” he said. “We get a break from the flu and RSV. You get through the season, and then you’re done. You can prepare for the next one. (Covid) is kind of always there.”
Flu and RSV levels now remain low in the United States, according to the latest update from the CDC. But vaccination rates against the three major respiratory viruses lagged during the winter season, and CDC advisers also looked ahead to the upcoming season with discussions about vaccine coverage recommendations for influenza and RSV.
On Wednesday, the CDC updated its recommendations on who should get the RSV vaccine. For the upcoming respiratory virus season, everyone 75 and older is encouraged to get the RSV vaccine, as well as people ages 60 to 74 who are at higher risk for severe illness.
These changes are intended to “simplify decision-making about RSV vaccine for clinicians and the public,” the agency said.
When it comes to infectious respiratory diseases, Plescia said, “people need to remember that there are things you can do to reduce your risk. And getting vaccinated is the number one thing.”
CNN’s Jen Christensen contributed to this report.