The respiratory illness RSV is still going strong in Chicago \u2014 an unusually late showing for the virus, which can strike infants especially hard.\u00a0<\/p>\n
RSV activity has moved from moderate to high in Chicago, according to the Chicago Department of Public Health. Though it\u2019s typical for RSV to spread more widely in the winter \u2014 along with illnesses like the flu and COVID-19 \u2014 it\u2019s often more prevalent earlier in the season.<\/p>\n
RSV activity in Chicago is still not as high as it was at its peaks in recent years, but it\u2019s stubbornly elevated for this time of year.\u00a0<\/p>\n
\u201cThis is not the typical pattern we see,\u201d said Dr. Larry Kociolek, an attending physician of pediatric infectious disease at Lurie Children\u2019s Hospital. \u201cWe\u2019re not seeing a ton of it, we just keep seeing it for a prolonged period, and now that we\u2019re heading into spring, it seems a bit more unusual.\u201d<\/p>\n
RSV, which stands for respiratory syncytial virus, can cause a runny nose, coughing and fever, and in most people is mild and resolves within a week or two. But the illness can be more severe in babies and young children, causing pneumonia and inflammation of the small airways in the lung.\u00a0<\/p>\n
Each year, about 2% to 3% of babies younger than 3 months old are hospitalized with RSV, according to the Centers for Disease Control and Prevention.\u00a0<\/p>\n
So far, two children with RSV have died this season in Chicago, according to the city health department.\u00a0<\/p>\n
For the week that ended March 7, emergency department visits by babies and children up to 4 years old for RSV in Chicago were more than three times higher than during the same week last year, according to the city health department.<\/p>\n
RSV concentrations in wastewater were \u201cvery high\u201d for the week that ended March 7, according to the health department.\u00a0<\/p>\n
The percentage of positive tests for RSV for the week that ended March 7 was also more than double the percentage for the same week during each of the last six years.<\/p>\n
Across the state as a whole, RSV activity is moderate, according to the Illinois Department of Public Health.\u00a0<\/p>\n
\u201cIt certainly has not slowed down,\u201d said Dr. Colleen Nash, associate professor of pediatric infectious diseases at Rush University System for Health. \u201cThere are still quite a few young infants coming to the general (hospital) floor and also requiring ICU level care as well.\u201d<\/p>\n
It\u2019s unclear exactly why RSV activity is still so high in mid-March. It may have to do with the weather (colder weather makes people crowd indoors more) or a later start to this RSV season, said Dr. Daniel Johnson, a pediatric infectious diseases specialist at UChicago Medicine.\u00a0<\/p>\n
\u201cHistorically, the RSV season ends sometime in March, but this year looks like it\u2019s going to be prolonged,\u201d Johnson said. \u201cThis is unusual but certainly not unprecedented.\u201d<\/p>\n
Another change is the increasing availability of relatively new vaccines and monoclonal antibodies to protect against RSV. In 2023, the U.S. Food and Drug Administration approved RSV vaccines for pregnant women and for older adults, as well as a monoclonal antibody for babies.<\/p>\n
Monoclonal antibodies are proteins made in laboratories that mimic the immune system\u2019s ability to fight off certain illnesses.<\/p>\n
The American Academy of Pediatrics recommends that pregnant women receive an RSV vaccine from weeks 32 through 36 of their pregnancies, from September through January, which can help protect their babies after they\u2019re born. If a pregnant mother doesn\u2019t get the vaccine, the AAP recommends babies receive a monoclonal antibody injection, if they\u2019re younger than 8 months old and were born during RSV season or heading into their first RSV season.<\/p>\n
The percentage of babies protected against RSV has been rising in Chicago since the products were approved.<\/p>\n
About 17% of Chicago infants born between April 1, 2023, and March 31, 2024, were immunized against RSV, either because their mothers got vaccines while pregnant or because they received monoclonal antibodies, according to the city health department.<\/p>\n
That number jumped to 58% for Chicago babies born during the following year.\u00a0<\/p>\n
Preliminary data suggests that percentage might be very similar or slightly higher by the end of this season, said Dr. Brian Borah, medical director of vaccine preventable disease surveillance at the Chicago Department of Public Health.\u00a0<\/p>\n
\u201cI think it\u2019s encouraging they\u2019re continuing to increase year over year,\u201d Borah said of the protection rates against RSV. \u201cI do think, however, there is a big gap in the number of infants that are not protected against RSV that I think needs attention as well. The health department is working really hard to close that gap.\u201d<\/p>\n
One challenge doctors are contending with are moves by the administration of President Donald Trump to scale back vaccine recommendations for children. Though many medical groups, including the American Academy of Pediatrics, have criticized those actions, the attempted changes have sowed even greater doubt about vaccines among some parents.\u00a0<\/p>\n