Compared with after a first COVID-19 illness, being re-infected with SARS-CoV-2, the virus that causes COVID, doubles the risk of later developing long COVID, or post-acute sequelae of COVID-19 (PASC) in children, teens, and young adults, according to a new preprint study posted on medRxiv.

The retrospective cohort study used data from the RECOVER consortium collected from 40 US children's hospitals from January 2022 through October 2023, when the Omicron variant was predominant. The study involved 465,717 patients 20 years old and younger with confirmed COVID-19 during the study period; the median age was 8 years. The study has not yet been peer-reviewed.

The population had a very low rate of long COVID, defined by the study authors as a diagnosis based on the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD10-CM) U09.9 diagnosis code of PASC. Only 208 patients were diagnosed as having the condition after their first SARS-CoV-2 infection, with 134 long-COVID patients identified after their second infection. The rate per million patients per 6 months was 903 after the first infection and 1,884 after the second infection.

Higher rate of long COVID plus many specific conditions

Compared with the first COVID-19 infection, a second infection was associated with twice the increased risk of a long-COVID diagnosis (relative risk [RR], 2.08; 95% confidence interval [CI], 1.68 to 2.59). The second infection was also tied to a 50% or greater increase in several specific long-COVID conditions, including myocarditis (RR, 3.60), changes in taste and smell (2.83), heart disease (1.96), acute kidney injury (1.90), generalized pain (1.70), arrhythmias (1.59), abnormal liver enzymes (1.56), and fatigue or malaise (1.50).

These findings emphasize the ongoing risk of PASC with reinfection, regardless of severity.

"These findings emphasize the ongoing risk of PASC with reinfection, regardless of severity, and suggest that the risk of PASC may be cumulative with each successive infection," the study authors write.

"Given that vaccination has been shown to reduce the risk of PASC, these findings underscore the importance of reinforcing public health efforts to promote vaccination among adolescents and younger children."

In a new cross-sectional analysis of 6,746 hospitalized adults aged 60 and older in 20 states, increased respiratory syncytial virus (RSV) vaccination was associated with being 75 years or older and having pulmonary disease. 

Vaccination was also associated with having at least grade 12 education or the General Educational Development equivalent. The study was published yesterday in JAMA Network Open. 

The authors assessed the patient characteristics associated with RSV vaccination among older adults hospitalized during the 2023-24 RSV season, the first year RSV vaccines were available. The cross-sectional study was conducted in 26 hospitals from October 2023 through April 2024.

The average patient age was 73 years, and 51.2% were female. In total, there were 700 RSV-vaccinated (10.4%) and 6,046 unvaccinated (89.6%) adults.

Being 75 years or older had an adjusted risk ratio (aRR) of 1.23 for RSV vaccination (95% confidence interval [CI], 1.10 to 1.38), which means a 23% higher rate of vaccination. Those with pulmonary disease had a 39% higher uptake (aRR, 1.39; 95% CI, 1.16 to 1.67), and those with compromised immune systems had a 30% higher rate (aRR, 1.30; 95% CI, 1.14 to 1.48).

Many don't know eligibility status 

The authors also interviewed RSV-negative adults included in the study about RSV knowledge. They found that 47.2% had not heard of RSV or were unsure, and 78.5% were unsure if they were eligible for RSV vaccine or thought they were not. Of note, 41.7% of unvaccinated patients reported being open to future RSV vaccination.

Knowledge of RSV disease and vaccine eligibility was lower among participants with less educational attainment .

"Knowledge of RSV disease and vaccine eligibility was lower among participants with less educational attainment and those residing in communities with high social vulnerability," the authors wrote.

he Centers for Disease Control and Prevention recommended RSV vaccination for adults 60 years or older in June 2023.

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported 15 more H5N1 avian flu detections in mammals, including domestic cats in four states.

The latest cats to test positive for the virus were from Kansas, Pennsylvania, Iowa, and Illinois. Sample collection dates range from March 19 through March 24. It's not clear if any of the cases are linked to exposure to contaminated raw food for cats.

Newly reported detections also include five skunks, three in New Mexico and two in Texas, two house mice in Iowa, an Arctic fox in Alaska, a red fox in New York, a raccoon in Kentucky, and a bobcat in Connecticut. 

 A few more confirmations in poultry, dairy cattle

Over the past 2 days, APHIS also confirmed two more outbreaks in poultry, one on a layer pullet farm in Indiana and the other involving a backyard flock in Maryland.

Also, APHIS confirmed one more detection in dairy cattle, a herd in California, raising the national total since March 2024 to 996, which includes 758 from California. 

Indian media outlets are reporting that a 2-year-old girl in Andhra Pradesh state has died from H5N1 avian flu.

According to Press Trust of India, the girl died on March 15 following hospitalization in Mangalagiri. The H5N1 findings were confirmed by the National Virology Institute based in Pune. 

No related infections were found in the girl's family members, and no poultry outbreaks were reported in Palnadu district where the girl lived. The girl's family said she had eaten raw chicken, which investigators say is her potential infection source.

South Asian clade connected to earlier infections

India reported its last human H5N1 infection in 2021, a fatal case in an 11-year-old boy who had an underlying medical condition. However, in May 2024, Australia reported an H5N1 infection in an Australian child who had recently traveled to India. The child had a severe infection but fully recovered.

So far, it's not clear what clade was involved in the newly reported cast. An older South Asian H5N1 clade called 2.3.2.1a is known to circulate in birds in India and Bangladesh and was implicated in the two earlier cases. Scientists, however, reported that the Australian child's virus was involved in a previously undetected reassortant of 2.3.2.1a, the global 2.3.4.4b clade, and low-pathogenic wild bird avian flu segments.