COVID-19 vaccination tied to less disease spread, shorter virus shedding

Transmission of COVID-19 was significantly lower, and viable virus was detected for a shorter period, in fully vaccinated patients and staff isolated at a South Korean hospital than in their partially vaccinated and unvaccinated counterparts, finds a study published yesterday in JAMA Network Open.

A team led by researchers from the University of Ulsan in Seoul studied SARS-CoV-2 transmission among 173 healthcare workers, patients, and guardians diagnosed as having mild COVID-19 from Mar 1, 2020, to Nov 6, 2021. The team also measured viral RNA with polymerase chain reaction and cultured daily saliva samples from 45 patients infected with the Delta variant from Jul 20 to Aug 20, 2021, to measure virus load and shedding.

Among the 173 adults in the transmission study, the median age was 47 years, 58% were women, and 29% were fully vaccinated against COVID-19. Secondary transmission was significantly less common among vaccinated than unvaccinated participants (3 of 43 [7%] vs 29 of 110 [26%]).

Median age among the 45 Delta-infected participants was 37 years, 31% were women, 13% were fully vaccinated, and 87% were partially vaccinated or unvaccinated. Although the initial viral RNA load was comparable between both groups, viable virus in cell culture was detected for substantially longer in partially vaccinated or unvaccinated participants than in the fully vaccinated (8 vs 10 vs 4 days, respectively).

"Data from this study provide important evidence that despite the possibility of breakthrough infections, COVID-19 vaccinations remain critically useful for controlling the spread of SARS-CoV-2," the study authors wrote.

In a related commentary, Camden Gowler, PhD; Prabasaj Paul, PhD; and Sujan Reddy, MD; all of the US Centers for Disease Control and Prevention, said that an understanding of viable viral shedding can lead to better parameterization of mathematical models that inform prevention guidance. "With timely analysis and dissemination, rich longitudinal data can inform rapid public health responses to outbreaks or pandemics," they wrote.
May 24 JAMA Netw Open study and commentary

MRI shows lung abnormalities in former COVID-19 patients

A special type of magnetic resonance imaging (MRI) found lung abnormalities in patients who had previously had COVID-19, even those who had not been hospitalized with the illness, according to a small UK study in Radiology.

The novel imaging technique, called Hyperpolarized Xenon 129MRI, or Hp-XeMRI, allows clinicians to assess ventilation and gas exchange in red blood cells, a process that cannot be seen on regular scans. Researchers from the University of Oxford and the University of Sheffield hypothesized that problems with gas exchange may be causing persistent breathlessness in patients with long COVID.

To conduct the study, 11 non-hospitalized long COVID (NHLC) participants and 12 post-hospitalized COVID-19 (PHC) participants were enrolled from June 2020 to August 2021. All participants reported breathlessness persisting 4 weeks past their diagnoses, and were compared to healthy controls who had never contracted COVID-19.

Both NHLC and PHC patients had normal computed tomography scans, but Hp-XeMRI imaging showed key differences in lung function but not structures.

"We saw that the ability of gas to transfer from the lungs into the blood stream was less in non-hospitalized patients in comparison to those hospitalized with COVID," said senior author Fergus Gleeson, MBBS, from the University of Oxford Department of Radiology in a Radiological Society of North America (RSNA) press release. "Furthermore, both groups of participants had lower dissolved phase Hp-XeMRI values than healthy participants, pointing to potential defects in either the lining of the lung or the surrounding blood vessels."

The authors said these findings could help explain some of the mysteries of long COVID, and guide clinicians in developing appropriate treatment plans.
May 24 Radiology study
May 24 RSNA press release

DR Congo reports fifth fatal Ebola case

The Democratic Republic of the Congo (DRC) reported another Ebola case, bringing the Equateur province outbreak total to 5, all fatal, though few details about the latest case were available.

Based on a brief situation update that the World Health Organization (WHO) African regional office posted today on Twitter, the patient died from his or her infection. The case appears to be listed as probable, based on earlier reports that the four previous illnesses were confirmed.

The outbreak is taking place across two health zones near the city of Mbandaka, the provincial capital. After a nearly 2-week lull, the DRC has now reported two cases over the past week. On May 20, officials reported an Ebola death involving a 12-year-old boy from Wangata health district.

This is the DRC's 18th Ebola outbreak and the third to strike Equateur province since 2018. Genetic evidence suggests the latest outbreak was likely triggered by a new introduction of the virus from animals to humans.
May 25 WHO African regional office tweet
May 23 CIDRAP News scan

CDC reports 36 more unexplained hepatitis cases in kids, 216 total

In an update on the unexplained hepatitis cases in children, the US Centers for Disease Control and Prevention (CDC) today reported 36 more potentially linked cases, raising the nation's total to 216.

So far, 38 states or jurisdictions—including Puerto Rico—have reported cases. The Utah Department of Health said on Twitter today that it has identified two Utah children younger than 10 who were treated for unexplained hepatitis and that the cases are reflected in CDC's update today. Officials said the two children were hospitalized with serious liver disease and have both recovered.

In an earlier update, the CDC said many of the recently reported cases are retrospective, with the investigation covering events reported since October 2021.

So far, scientists haven't established a definitive cause, but a possible role for adenovirus infection is a strong lead. Canada recently reported 10 cases from 4 provinces. More than 600 cases have been reported so far, globally.

In a related development today, the European Centre for Disease Prevention and Control (ECDC) posted guidance on testing kids experiencing unexplained hepatitis.
CDC hepatitis update page
May 25 Utah Department of Health tweet
May 20 Public Health Agency of Canada update
May 25 ECDC technical guidance

Avian flu strikes more backyard flocks in Idaho and Washington

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today reported two more highly pathogenic avian influenza outbreaks in poultry, both involving backyard flocks in the western part of the country.

Idaho reported the virus at a facility in Ada County near Boise. Also, Washington reported an outbreak at an address in King County in the Seattle area.

The events bring the nation's outbreak total to 353, including 183 in commercial poultry. So far the outbreaks have led to the loss of 38.02 million birds in 35 states. They involve the Eurasian H5N1 strain, which has sickened poultry and wild birds in multiple world regions.
USDA APHIS poultry outbreak update page