News Scan for Dec 01, 2021

News brief

Data suggest third COVID vaccine dose reduces infection, hospitalization

A third dose of the Pfizer/BioNTech mRNA COVID-19 vaccine appears to counteract waning vaccine protection in the short term, according to a preliminary case-control analysis of more than 500,000 coronavirus tests in Israel.

In the retrospective study, published yesterday in JAMA Internal Medicine, a team led by Maccabi Healthcare Services researchers found a 1.8% SARS-CoV-2 infection rate after a booster dose, compared with 6.6% after two vaccine doses. Participants receiving the booster also seemed to be at lower risk for hospitalization.

The study involved 306,710 Israelis 40 years and older who received two or three doses of the vaccine and did not have a previous COVID-19 infection. Data were collected from Mar 1, 2020, to Oct 4, 2021—a period that included the emergence and eventual dominance of the Delta (B1617.2) variant—while analysis focused on the period of Aug 1, 2021, when third doses were rolled out, to Oct 4. Booster recipients were tested for COVID-19 five times over the study period.

Positive tests were most common in those who did not receive a booster and those who received a booster within the past week; they were least common among those who received a booster more than 2 weeks before.

The estimated odds ratio for infection was 0.14 for those receiving two doses relative to those receiving boosters, for an 86% reduction in the odds of infection.

"However, these results should be interpreted with caution because a reduction in the odds of hospitalization was already evident in the first week after receipt of the booster when an effect would not be expected," the study authors noted

The chances of hospitalization among those who received a booster were 92% to 97% lower than among those who received two doses. "The interpretation of these estimates for hospitalization is challenging; however, the apparent immune response of the booster was evident as soon as a few days after its receipt (87% measure of effectiveness at 0-6 days)," the study authors wrote.

More follow-up is needed to determine how long third-dose immunity lasts, the researchers concluded.
Nov 30 JAMA Intern Med study

Children with poorly controlled asthma at higher risk of severe COVID-19

A study yesterday in The Lancet Respiratory Medicine of Scottish children shows that 5- to 17-year-olds with poorly controlled asthma are three to six times more likely to be hospitalized with COVID-19 compared with those without asthma. The authors of the study said children with asthma should consider vaccination against COVID-19 as soon as possible.

The study was based on health records from more than 750,000 children. Among those, 63,463 had asthma, and among that group, there were 4,339 confirmed cases of COVID-19 from Mar 1, 2020, to Jul 27, 2021. Sixty-seven of those children required hospitalization.

Children with poorly controlled asthma—defined as recent hospitalization for asthma, or two or more courses of oral corticosteroids—were more likely to be hospitalized. For children with a recent hospital admission for asthma, the hazard ratio (HR) was 6.4, compared to 1.6 for children with controlled asthma. Children who had reported steroid use at least twice in the past had an HR of 3.53.

Among children without asthma, there were 40,231 confirmed cases of COVID-19, 382 of which involved hospitalization.

"The key takeaway from this study is that keeping children's asthma under control is critical, as this greatly reduces the risk of COVID-19 hospitalisation," said senior author Aziz Sheikh, PhD, from the University of Edinburgh, Scotland, in a Lancet press release. "Vaccinating those with poorly controlled asthma offers an additional important layer of protection from serious COVID-19 outcomes."

In a commentary published on the study in the same journal, two UK experts who were not involved in the study point out that even with poorly controlled asthma, serious complications from COVID-19 were still extremely rare in Scottish children.

"Careful decision making around the delivery of the vaccine to children younger than 12 years is essential. Although children with asthma have been identified as having an increased risk of being admitted to hospital compared with peers without asthma, the overall risk remains very low," they write.
Nov 30 Lancet Resp Med study
Nov 30 Lancet press release
Nov 30 Lancet Resp Med commentary

Stewardship / Resistance Scan for Dec 01, 2021

News brief

Study suggests contact precautions for MRSA, VRE can be safely removed

A study conducted in 15 hospitals found that discontinuing contact precautions for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) did not result in increased healthcare-associated infection (HAI) rates, researchers reported today in Infection Control & Hospital Epidemiology.

To determine the impact of removing contact precautions for MRSA and VRE, which are recommended by the Centers for Disease Control and Prevention to reduce transmission but are controversial because of associations with patient harms, the researchers performed a retrospective, quasi-observational study at 15 acute care hospitals in a Pennsylvania healthcare system. Twelve of the hospitals (the intervention hospitals) had removed MRSA and VRE contact precautions after a policy change recommended doing so, and 3 (non-intervention hospitals) continued them.

The researchers compared HAI rates at the hospitals during the 12 months before and after discontinuation. To predict conditions where contact precautions may safely be removed, they correlated selected baseline hospital characteristics and infection prevention practices with HAI rate changes.

Aggregated HAI rates from intervention hospitals before and after discontinuation of contact precautions were 0.14 and 0.15 MRSA HAI per 1,000 patient days (P = .74), 0.05 and 0.05 VRE HAI per 1,000 patient days (P = .96), and 0.04 and 0.04 MRSA laboratory-identified (LabID) events per 100 admissions (P = .57). No statistically significant rate changes occurred between the intervention and non-intervention hospitals.

All successful hospitals had low baseline MRSA and VRE HAI rates and high hand hygiene adherence. No correlations were found between rate changes after discontinuation and the assessed hospital characteristics and infection prevention factors, although there was an increase in MRSA HAIs in hospitals with a higher proportion of semiprivate rooms (P = .04).

"Our results suggest that contact precautions for endemic MRSA and VRE can be safely removed under the right conditions without increasing HAI in a large, diverse health system, which would lead to significant cost savings on isolation gowns," the study authors write. "The exact conditions necessary require further investigation, but this study supports the importance of high rates of hand hygiene and low rates of HAI with MRSA and VRE."
Dec 1 Infect Control Hosp Epidemiol abstract

Intensive malaria control measures linked to reduced antibiotics in kids

Implementation of intensive malaria control efforts in Uganda was associated with a 70% reduction in antibiotic use in children, researchers reported yesterday in BMC Medicine.

In the study, Ugandan, US, and UK researchers analyzed the medical records of two cohorts of children (ages 6 months to 10 years) in a high-transmission area of Uganda where distribution of long-lasting insecticidal nets (in 2013 and 2017) and sustained indoor residual spraying (IRS) of insecticides (in 2014, with repeated rounds through 2019) were initiated. They then compared the incidence of antimalarial and antimicrobial treatments—which are frequently used for the acute bacterial and viral infections that are common in malaria-endemic settings—before and after the vector control measures were implemented.

Comparing the period prior to the implementation of IRS to the period after IRS had been sustained for 4 to 5 years, the adjusted incidence of malaria treatments decreased from 2.68 to 0.05 per person-year (incidence rate ratio [IRR], 0.02; 95% confidence interval [CI], 0.01 to 0.03; P < 0.001), and the adjusted incidence of antibiotic treatments decreased from 4.14 to 1.26 per person-year (IRR, 0.30; 95% CI, 0.27 to 0.34; P < 0.001).

The reduction in antibiotic usage was primarily associated with fewer episodes of symptomatic malaria and fewer episodes of fever with sub-microscopic parasitemia, both of which were frequently treated with antibiotics.

The study authors say the high number of antibiotic treatments averted (mostly amoxicillin) could help reduce selection pressure and help slow the spread of antimicrobial resistance in Uganda and other countries where malaria is endemic.

"We found that investments in malaria control may have broader health benefits for children beyond malaria," they wrote. "Future studies should investigate the association between malaria control and antibiotic prescribing practices in other settings to further explore the impact on health systems and to inform strategies to mitigate the overuse of antibiotics and the threat of antimicrobial resistance in malaria-endemic settings."
Nov 30 BMC Med study