A study of patient data from the 2019-20 US flu season found that the MF59-adjuvanted flu vaccine was more effective than the high-dose flu vaccine at preventing serious flu complications in older adults with risk factors, researchers reported late last week in Open Forum Infectious Diseases.

The MF59-adjuvanted trivalent influenza vaccine (aTIV) and the high-dose trivalent influenza vaccine (HD-TIV) are both designed for adults age 65 and older, who are at serious risk from serious flu complications. An adjuvant is an immune-boosting agent added to vaccines.

Previous studies have found the two vaccines to have similar effectiveness in older adults, including those who have at least one underlying health condition known to increase their risk of experiencing severe flu. But there is limited research on how multiple concurrent high-risk conditions affect vaccine effectiveness.

aTIV more effective in adults with multiple risk factors

Using electronic health record data linked with pharmacy and medical claims, researchers estimated the relative vaccine effectiveness (rVE) in 1,115,725 aTIV recipients and 2,561,718 HD-TIV recipients from August 2019 through January 2020. The primary measure was prevention of influenza-related medical encounters (IRMEs). The secondary outcome was outpatient IRME and flu- and pneumonia-related hospitalizations.

Among older adults with risk factors for complications, aTIV was more effective than HD-TIV at preventing any IRME, with an rVE of 12.5% (95% confidence interval [CI], 10.0% to 15.0%) for adults with 1 or more risk factor, 18.4% (95% CI, 13.7% to 22.8%) for adults with 1 or 2 risk factors, and 10.4% (95% CI, 7.4% to 13.3%) for adults 3 or more risk factors. No difference in rVE was observed among older adults with no risk factors. 

The same trends were observed for the secondary outcomes of outpatient IRMEs and flu- or pneumonia-related hospitalizations.

The study authors suggest the broader immune response provide by the MF59 adjuvant may account for the higher vaccine effectiveness observed among the most vulnerable in the population study, but say further research is needed to investigate how the immune response generated by aTIV contributes to overall vaccine effectiveness across populations with different risk profiles.

Although memories of COVID-19 lockdowns in Danish school children dimmed in detail and emotion from 2020 to 2021, their mental health remained poor, particularly among girls, Aarhus University–led researchers report in Child Development.

The researchers asked 247 students to write about their memories of the first lockdown and their psychological symptoms three times from June 2020 to June 2021. The students, recruited from five public and private schools, had a median age of 11.9 years.

Denmark closed schools from March 11 to April 17, 2020, for younger students and to May 18 for older ones. A second closure occurred from December 17, 2020, to May 6, 2021. Other measures taken were restaurant closures, gathering bans, physical-distancing policies, and work-from-home orders.

Older students, teen girls most emotional

Students whose memories were more negative and contained more COVID-19 information fared worse over time, which may mean that they integrated lockdown experiences more profoundly in their development and sense of self, the researchers said.

The US Centers for Disease Control and Prevention (CDC) has announced a Salmonella outbreak linked to contact with small pet turtles, similar to several other outbreaks linked to the animals in previous years.

In the latest outbreak, the CDC has received reports of 51 illnesses from 21 states, with 23 patients hospitalized. No deaths have been reported.

Two subtypes are tied to the outbreak, Salmonella Stanley (38) and Salmonella Poona (13). Illness onsets range from August 20, 2023, through July 9, 2024. More than a third of the patients are children younger than 5 years old.

Of 41 sick people who were interviewed, 27 (66%) had contact with pet turtles. Of 23 people who reported the size of the turtles, 21 said they had contact with turtles with shells less than 4 inches long. A similar outbreak in 2023 resulted in at least 80 illnesses in 24 states.

Testing of turtles identifies outbreak strain

Genetic sequencing of Salmonella samples from sick patients suggests that their illnesses are closely related, hinting at the same infection source. Also, California officials collected a sample from a sick patient's turtle in June, and tests revealed Salmonella Poona that was closely related to bacteria that infected humans. Testing of turtle and environmental samples from Illinois also yielded the Salmonella Poona outbreak strain.

The patient from California had purchased the turtle from a street vendor, and the person from Illinois had gotten the turtle at a souvenir shop. A survey of sick patients found that people had bought the turtles at those and other outlets, which also included online retailers.

The CDC urged people not to buy turtles with shells less than 4 inches long due to the well-known infection risk, and it noted that there's federal ban on the sale and distribution of small turtles as pets.

• When the World Health Organization (WHO) mpox emergency committee met on August 14 to discuss the quickly evolving developments in Africa, it unanimously recommended that the situation warrants a public health emergency of international concern (PHEIC). In accepting the group's recommendation the same day, the WHO's director-general said the group would soon release its temporary recommendations and full report for countries, which the WHO published today. The recommendations cover but are not limited to the Democratic Republic of the Congo, Burundi, Kenya, Rwanda, and Uganda. Among several recommendations, the emergency committee urged countries to prepare for mpox vaccination for emergency response by convening immunization advisory groups. It also emphasized the importance of standing recommendations that the WHO issued when it called the end of the earlier PHEIC for the global spread of the clade 2 virus.
• Massachusetts and Vermont last week reported their first human Eastern equine encephalitis (EEE) cases of the year, according to notifications from the state health departments. The Massachusetts Department of Public Health said its case, the first since 2020, involved a man in his 80s who was exposed in Worcester County. Meanwhile, the Vermont Department of Health reported an EEE illness in a man in his 40s from Chittenden County. He was hospitalized in the middle of July, but has now been released. The case marks Vermont's first since 2012. EEE is a rare mosquito-borne illness that can lead to severe neurologic complications. Transmission is most common in and around freshwater hardwood swamps in Atlantic and Gulf Coast states and in the Great Lakes region. In its most recent update on August 13, the Centers for Disease Control and Prevention said it had received a report of only one case so far this season, involving a patient from New Jersey.
• The Food and Drug Administration on August 16 announced that it has approved the first at-home over-the-counter test for syphilis, which detects human antibodies to Treponema pallidum in human blood. The test, made by NOWDiagnostics, produces a result in 15 minutes and is designed to alert the user for a potential follow-up, which would require confirmation testing by a healthcare provider. Syphilis cases in the United States have been steadily rising since 2018, with congenital cases up even more sharply.