The flu is ramping up after a slow start to the season.
Positive tests rose 12% for the week ending Dec. 21, compared to the week prior, according to data released Friday by the Centers for Disease Control and Prevention. More than 12,000 people were hospitalized from the virus, up from nearly 9,000 the week prior.
“We’re seeing upticks in both our inpatient hospitalizations as well as our community based metrics such as percentage of emergency room visits and test positivity,” said Dr. Scott Roberts, associate medical director for infection prevention at Yale New Haven Health. “I certainly expect they’re going to continue to go up since we’re really entering flu season right now.”
Typically, flu activity starts to pick up around Halloween and peaks in February. This year, however, the virus got off to a later start, with activity only just picking up in recent weeks.
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It’s not clear why that is, Roberts said.
“We’re still seeing the interplay of Covid here and how that is altering the other respiratory viral dynamics that we have,” he said. “We certainly are not back to the pre-Covid state of normalcy for most respiratory viruses.”
In the Midwest, doctors are also seeing a similar rise in flu activity.
“Over the last one to two weeks we’ve been seeing a significant increase in flu as well as respiratory syncytial virus in our patient population,” said Dr. Sindhu Aderson, medical director for the central region of Northwestern Immediate Care in Chicago.
Flu activity was highest in Louisiana and Oregon the week ending Dec. 20, the CDC said. Activity was also high throughout the South and along the West Coast.
How severe is this season’s flu?
So far this season, there have been an estimated 3.1 million illnesses, 37,000 hospitalizations and 1,500 deaths from the flu, according to the CDC.
The last flu season, the CDC estimated that the virus was associated with 40 million illnesses, 18 million medical visits, 470,000 hospitalizations, and 28,000 deaths. While those with chronic conditions and people over the age of 65 are at a higher risk of severe illness, people of all ages can get very sick.
At Yale New Haven Hospital, flu numbers are approximately half as high as they were this time last year, Roberts said, adding that he could count on one hand the amount of severe cases they’ve had so far.
“We’ve seen a handful of severe cases with people requiring mechanical ventilation even in some relatively healthy people with few comorbidities,” Roberts said.
Five pediatric deaths were reported this week, the CDC said. A total of nine children have died so far this year.
Dr. Sara Siddiqui, a pediatrician at NYU Langone Health in New York City, is seeing more children testing positive for the flu.
“It becomes an exponential increase as Influenza can spread via aerosol droplets so schools and daycares are usually where we see the spread occuring,” Siddiqui wrote in an email. “Families with children are also seeing a rise in adult exposures who also become sick with respiratory viral illnesses.”
Two strains of influenza A — called H1N1 and H3N2 — accounted for the majority of positive tests. Both strains can cause severe illness.
The CDC also said that five cases of H5 were reported. H5, or bird flu, is distinct from the seasonal flu and human-to-human transmission has not been detected in the U.S., the agency said.
Is it too late to get a flu shot?
The number of adults who have gotten their flu shot this year is similar to this time last year: a little under 42%, according to the CDC. Fewer kids, however, have gotten their flu shot this year.
Experts say the best way to protect yourself and help reduce the chances of getting very sick is to get a flu shot. While it’s too early to say how well this year’s flu shot is working, the flu vaccine is typically between 40-60% effective and recommended for everyone ages 6 months and older.
In previous seasons, 80% of children who died from the flu virus were unvaccinated, according to the CDC.
A study published Friday in JAMA Network Open led by researchers at the CDC looked at pediatric data from nearly 16,000 children from 2015 to 2020 and found that the flu shot was at least about 50% effective at preventing illness at all levels of severe flu illness.
The flu shot is estimated to have prevented 9.8 million illnesses, 4.8 million medical visits, 120,000 hospitalizations and 7,900 deaths last year.
“I think the best time is now” for a flu shot, said Roberts. “The second best time is tomorrow.”
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