COVID-19 Scan for Oct 18, 2021

News brief

SARS-CoV-2 dose not linked with COVID-19 severity, review says

SARS-CoV-2 dose may affect infection rates, but current data do not show an association between viral dose and COVID-19 severity, according to a review of more than 100 SARS-CoV-2 studies that looks at COVID-19 infectious dose, viral load, severity, and variants.

The aggregated findings were included in Clinical Infectious Diseases late last week and written by US researchers, led by scientists with the University of Minnesota's Center for Infectious Disease Research and Policy, publisher of CIDRAP News.

An infectious dose, the researchers summarized, is often expressed as either the smallest quantity of virus that leads to infection or the median infectious dose. As the review noted, infectious virus is usually not shed beyond 8 to 10 days after symptom onset. Also, in animal studies involving SARS-CoV-2, most infections needed high doses affecting the upper mucosa to result in clinical disease, and infected hamsters and ferrets have been able to transmit the disease to naive animals by contact, contaminating surfaces, and through aerosols.

Other highlighted research includes a 2021 study looking at hospitalizations and severe disease outcomes in healthcare workers that showed a "paucity of evidence" linking dose with severity. Another 2020 study suggested that age was a much greater factor in healthcare workers, The researchers also outline frequently associated health and demographic factors as well as observed differences from variants of concern.

"We found that there is some evidence of a relationship between dose and infection based on animal studies and human epidemiology but minimal data supporting a relationship between dose and disease severity. Instead, host responses and potentially viral genotype primarily determine disease outcomes," the researchers write.

"Non-pharmaceutical interventions may limit the inoculum dose from an exposure, thereby reducing the risk of infection, but they are unlikely to individually have an impact on COVID-19 severity."
Oct 15 Clin Infect Dis paper


Asymptomatic COVID-19 may significantly contribute to transmission

Seventy-five percent of asymptomatic COVID-19 outpatients had mean to high RNA viral loads, and 50.6% of those whose samples were tested with culture assays had live cultures, according to a study today in Scientific Reports.

The researchers say this indicates that COVID-19 asymptomatic adult outpatients could play a large role in perpetuating COVID outbreaks. The study was conducted before the much more transmissible Delta (B1617.2) variant was circulating.

The study involved 17,911 French adults who were tested for COVID-19 in the Champagne-Ardenne area from Jun 4 to Sep 20, 2020. About 2.8% were positive based on samples from the upper respiratory tract, and 36.3% (180) of those people had asymptomatic cases. While asymptomatic patients had more low viral loads than symptomatic patients (25% vs 11.7% had cycle threshold [Ct] values 30 or higher), 75% of asymptomatic patients still had high viral loads, with a median value slightly higher than those in symptomatic patients (21.60 vs 22.57 Ct among all values below 30, P = 0.029).

In addition, 83 asymptomatic patients had their samples tested by the culture assay protocol: 50.6% were positive.

"Only the viral loads of patients who were sampled between 8 and 28 days after symptom onset were significantly lower than those of asymptomatic patients (P=0.041)," the researchers write, noting that as expected, viral RNA loads appeared to be highest during or before symptom onset. Still, they conclude, "Our findings indicate that COVID-19 asymptomatic adult outpatients are significant viable SARS-CoV-2 shedders in their upper respiratory tract, playing a major potential role as SARS-CoV-2 transmitters in various epidemiological transmission chains, promoting COVID-19 resurgence in populations."

Of the COVID-19 positive study participants, 66.0% were women, and the mean age was 41.8 years. In the asymptomatic group, 60.1% were women, and the mean age was 32.3 years. The overall median Ct value was 23.57 cycles.
Oct 18 Sci Rep study


COVID-19 vaccine lotteries did not increase uptake, study finds

COVID-19 vaccine-related cash drawings in 19 states did not increase uptake, according to a research letter published late last week in JAMA Health Forum.

The researchers looked at daily state-level COVID-19 vaccination data before and after cash drawings announcements, as well as the data from the rest of the US states that didn't have those incentives, from Apr 28 to Jul 1. Vaccination appointments were widely available, and during the study period, 37.2 million first doses of a COVID vaccine were administered in the country, with 19.2 million of those in the states with cash drawings.

Adjusted regression estimated that the cash drawings were associated with –0.06 daily vaccination per 1,000 people (95% confidence interval [CI], –0.43 to 0.30). This finding was supported by the researchers' event-time estimates, which showed no statistical significance using both a conventional and novel model that better accounted for staggered announcements.

"With the upper bound of the 95% CI for the first-dose estimate of 0.30 daily vaccinations per 1000 population, we can rule out fairly small associations between lottery announcements and vaccinations," the researchers write. "If the cash-drawing announcements had been associated with 70% of US adults receiving a first vaccine dose by July 4 (President Biden's stated goal), we would have expected an estimate of approximately 1.22 daily vaccinations per 1000 population."

The researchers speculate that the null impact could be because lottery-style cash drawings weren't assured-enough incentives or because the campaigns didn't have enough vaccination-related information in addition to the prize announcement.
Oct 15 JAMA Health Forum study

Three more Ebola cases reported in the DRC

Three more Ebola cases, one of them fatal, were reported in the Democratic Republic of the Congo's (DRC's) latest resurgence near Beni in North Kivu province, according to a World Health Organization (WHO) DRC office tweet today. The case total is now five including three deaths, said the World Health Organization (WHO) African regional office today on Twitter.

As of Oct 17, health officials have identified 369 contacts and are monitoring 308 of them. The latest cases were in the Butsili health area, which is in Beni Health Zone, one of the epicenters of the large 2018-20 outbreak.

Officials have said preliminary genetic testing suggests that the outbreak is linked to the earlier large outbreak, an event that was centered in North Kivu province. In risk assessments of the latest cluster, the WHO said sporadic cases in the wake of major outbreaks are expected as survivors can carry the virus in immune-protected parts of the body for longer than 6 months. Also, animal species in the DRC can harbor the virus.

The first confirmed case in the latest resurgence is a young boy who died following the deaths of three of his neighbors, who had been sick with Ebola-like symptoms. Earlier this year, a similar flare-up in a different part of North Kivu province resulted in 12 cases, 6 of them fatal.
Oct 18 WHO African regional office tweet
Oct 18 WHO DRC office


Resistant ICU infections linked to longer hospital stays, excess costs

Antibiotic-resistant infections acquired in the intensive care unit (ICU) were associated with significant increases in excess hospital days and healthcare costs in three southern European countries, according to a study published today in Infection Control & Hospital Epidemiology.

Using data from the European Surveillance System, researchers studied a cohort of adult patients who developed ICU-acquired infections related to an invasive procedure at hospitals in Spain, Portugal, and Italy from 2008 through 2016. They used regression, matching, and time-to-event methods to analyze the association between antibiotic-resistant infections and excessive length of stay (LOS), controlling for several confounding factors and time-dependent biases. They also calculated the associated economic burden of excess resource utilization for each country.

In total, 13,441 patients were included in the analysis. Of these patients, 4,106 (30.5%) were infected with antibiotic-resistant organisms and matched 1:1 to patients with susceptible infections. The median age of all patients was 62 years. In the fully adjusted estimates, the association between resistance status and excess LOS was 2.76 days in the linear model (95% confidence interval [CI], 1.98 to 3.54), 2.60 days in the matched model (95% CI, 1.66 to 3.55), and the hazard ratio was 1.15 in the Cox regression model (95% CI, 1.1 to 1.19).

These estimates, alongside the prevalence of resistance, translated into direct hospitalization attributable costs per ICU-acquired infection of 5,224€ (US $6,066) for Spain, 4,461€ (US $5,180) for Portugal, and 4,320€ (US $5,016) for Italy.

"These results contribute significantly to the antimicrobial resistance literature that explores the consequences of resistance on health and economic outcomes," the study authors write.
Oct 18 Infect Control Hosp Epidemiol abstract


Elbow bumps may transfer MRSA just as much as fist bumps

In another study today in the same journal, researchers from the Cleveland VA Medical Center reported that both a fist bump and an elbow bump are associated with frequent transfer of methicillin-resistant Staphylococcus aureus (MRSA).

Elbow bumps have been increasingly used as greetings over fist bumps and handshakes with the idea that they lessen the potential for pathogenic microorganism transfer. To test this hypothesis, the researchers enrolled 40 patients in isolation for MRSA colonization and paired them with a research staff member wearing sterile gloves and a piece of cotton cloth over their elbows. Each MRSA-colonized patient performed one greeting with a staff member using their right fist or elbow, and one greeting using their left fist or elbow, with the order of the greetings alternating among consecutive participants. The researchers then analyzed the fists and elbows of the MRSA-colonized patients, along with the gloves and elbow cloth from the staff members, for the presence of MRSA.

The results showed no significant difference in the frequency of MRSA transfer for the fist bump compared with the elbow bump (10 of 40 [25%] vs 6 of 40 [15%]). Even so, MRSA was recovered more frequently from the fist versus the elbow of the MRSA-colonized patients (16 of 40 [40%] vs 9 of 40 [22.5%]). Also, significantly more MRSA colonies were recovered from fists compared with elbows, and more MRSA colonies were transferred via fists.

The study authors note that the findings of the study suggest that noncontact greetings should be encouraged instead. "In addition to promoting noncontact greetings, there is a need to improve patient hand hygiene and to identify other strategies to reduce transfer of pathogens by hands and clothing," they write. 
Oct 18 Infect Control Hosp Epidemiol abstract


H5N6 avian flu hospitalizes farmer in China

China reported another human H5N6 avian flu infection, marking its 24th of the year, according to a statement from Hong Kong's Centre for Health Protection (CHP).

The patient is a 60-year-old woman from the city of Changde in Hunan province, located in southern China. She worked as a farmer and was exposed to dead poultry before her symptoms began on Oct 3. The woman was hospitalized on Oct 13, where she is listed in critical condition.

Since 2014, China has reported 48 H5N6 cases, which are often severe or fatal. H5N6 is known to circulate in poultry, mainly in some Asian nations. So far, China and Laos are the only ones to report human cases.
Oct 18 CHP statement

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