COVID-19 Scan for Feb 11, 2021

News brief

Pre-, asymptomatic COVID cases lead to half of transmissions, study finds

Presymptomatic and asymptomatic COVID-19 cases contributed at least 50% of transmissions during New York City's first COVID surge, according to a study published yesterday in Proceedings of the National Academy of Sciences.

The researchers applied a stochastic epidemiologic model that integrated daily changes in testing capacity to New York City's case and serologic data from Mar 1 to Jun 1, 2020, and Mar 8 to Apr 19, 2020, respectively. While asymptomatic transmission rates are still unknown, the researchers report that asymptomatic and symptomatic cases had reproduction rates of at least 3 in every reasonable simulation—above the estimated 2 to 3 rate reported in many cities where interventions were already in place. (Reproduction rates are the number of secondary cases caused by a primary case.)

If asymptomatic infections transmit at similar rates compared with symptomatic infections, they write, the reproductive number for all COVID-19 cases is 3.2 to 4.4. However, if asymptomatic infections transmit at a lesser rate, then symptomatic cases may have a reproductive value of 3.9 to 8.1, which could support superspreader observations.

Testing policies and data should be more transparent to strengthen epidemiologic models, the researchers write. "Testing only symptomatic cases can result in at least a fourfold increase in the IFR [infection fatality ratio] that is calculated," the researchers write. "Limitations in testing capacity may also impact the estimated IFR."

Regarding New York City, the results indicated that COVID-19 transmissions began in February, which could be attributed to either the lag time between infection onset and hospitalization or because of a dosage-dependent effect in which more SARS-CoV-2 contact could lead to higher disease severity. The researchers also found that when the city implemented its lockdown, COVID transmission rate dropped 76.0% to 87.6%.

Even though the study could only estimate reproduction rates, the researchers say, "The strong consistent contribution to community transmission from cases without symptoms observed across scenarios supported by the data should be considered when formulating public health intervention strategies."
Feb 10 Proc Natl Acad Sci study


Factoring in chills, other COVID-19 symptoms may optimize testing

While fever, cough, loss of smell, and loss of taste are the four classic COVID-19 symptoms, data from the REal-time Assessment of Community Transmission (REACT) study indicate that approximately 60% of infected people don't display these symptoms in the week leading up to their test.

The study, published yesterday as a non–peer-reviewed preprint by Imperial College London, used sample swab and questionnaire data from 1,147,349 UK residents ages 5 and up. The researchers found that, from June through December 2020, the presence of one of the classic symptoms had a 5.5% positive predictive rate, and experiencing one of the other 22 symptoms had a 0.8% positive predictive rate. In January 2021, when B117 accounted for about 86% of cases, classic symptoms had a 20.7% positive predictive rate and other symptoms had a 2.5% predictive rate.

Overall, chills were a common symptom across all ages, but Least Absolute Shrinkage and Selection Operator stability selection also indicated that certain age-groups were more likely to display headaches (children 5 to 17 years), appetite loss (18 and older), and muscle aches (18 to 54). When comparing pre- and post-B117 dominance, the researchers noted that the variant's presence may have increased the prevalence of coughing and decreased the prevalence for loss of smell.

The researchers say if everyone with at least one classic symptom was tested, only 55% of all symptomatic cases would have been identified in January 2021. If test strategies were adapted to accommodate the stability selection results, though, 76% of all symptomatic cases would have been identified in January.

"The ~40% increase in case detection (above that for at-least-one-of-four symptoms) would involve a 2.7-fold increase in the number of tests allocated to the symptomatic population in England," the researchers write.

"These new findings suggest many people with COVID-19 won't be getting tested—and therefore won't be self-isolating—because their symptoms don’t match those used in current public health guidance to help identify infected people," Paul Elliott, MBBS, PhD, said in an Imperial College London article.
Feb 10 Imperial College London study
Feb 10 Imperial College London article

News Scan for Feb 11, 2021

News brief

Second fatal Ebola case reported in DRC resurgence

A second fatal Ebola case was reported in the Democratic Republic of the Congo (DRC), in a person from North Kivu province, where the first case was recently reported in the wife of an Ebola survivor, according to media reports that cited a joint statement from the DRC and the World Health Organization (WHO).

African media reports said the second case involves a 60-year-old woman from Lubero in North Kivu province. who had contact with the first case.

Also, the WHO yesterday posted new details about the first patient, whose illness resulted in   high-risk exposures. The 42-year-old woman sought care for nasal bleeding on Jan 25 and was referred to two different health centers as her symptoms worsened. Health workers obtained a blood sample for Ebola testing, given that her husband was an Ebola survivor. His samples have tested negative since Sep 28.

She was admitted to an intensive care unit near Butembo on Feb 4, where she died the same day. On Feb 5, she was buried without Ebola safety protocols, and the following day her samples tested positive for Ebola. So far, 117 contacts have been identified for follow-up.

The WHO said resurgence is not surprising because of exposure to animal hosts or to body fluids of Ebola survivors, who may harbor the virus in immune protected body sites, including the testes and eyes.
Feb 11 NPR report
Feb 11 7SUR7 media report
Feb 10 WHO statement


Study confirms safety, effectiveness of rabies treatment in children

Results from the first and only pediatric trial of a human rabies immunoglobulin treatment currently available in the United States show it's safe and effective in children under the age of 17, according to a new study in Human Vaccines & Immunotherapeutics.

The treatment, known as KEDRAB (Rabies Immune Globulin [Human]), is currently used to prevent rabies in adults as part of post-exposure prophylaxis (PEP).

Now, based on study results from Israel and the United States, data on PEP with KEDRAB are being submitted to the US Food and Drug Administration for review as the first rabies treatment for the pediatric population.

"Evidence from this KEDRAB US Pediatric Trial confirms that this product addresses an unmet need in children who may have been exposed to rabies, and gives healthcare providers confidence when preventing this deadly condition in countless numbers of young patients across the US," said first author Nicholas Hobart-Porter, DO, of the University of Arkansas for Medical Sciences and Arkansas Children's Hospital, in a press release from Taylor & Francis, publisher of the journal.

In the study, 30 participants who had suspected or confirmed rabies exposure received KEDRAB over an 84-day period (including a 3-month follow-up). The participants received 20 IU/kg KEDRAB infiltrated into detectable wound sites, with any remainder injected intramuscularly, and at the same time began the four-dose series of rabies vaccine. None of the participants developed active rabies infections. There were no significant adverse events recorded.

Rabies, transmitted through animal bites, is 100% fatal, and children account for 40% of the world's rabies cases, according to the World Health Organization.
Feb 9 Hum Vaccin Immunother
Feb 9 Taylor & Francis
press release


H5N8 avian flu strikes more poultry farms in Europe

European countries reported more highly pathogenic H5N8 avian flu outbreaks in poultry, with Latvia the latest of many to report a detection of the virus in wild birds, according to notifications from the World Organization for Animal Health (OIE).

Germany reported three more outbreaks at turkey and broiler farms in two different states, one in Brandenburg and two in Mecklenburg-Vorpommern. The events began from Feb 5 to Feb 8, and taken together, the virus killed 5,127 of 77,500 susceptible birds.

Ukraine reported an outbreak in backyard birds in Donetsk, which began on Feb 7, killing 23 of 48 birds. Also, Poland reported three outbreaks in three provinces, which started from Feb 2 to Feb 4, killing 952 of 21,237 birds.

Meanwhile, Latvia reported H5N8 in two mute swans found dead on Feb 9 in Jurmala, not far from Riga. And in other developments, Bulgaria reported four H5 outbreaks at poultry farms in Pleven province, which began from Feb 5 to Feb 8. Among all the locations, the virus killed 1,647 of 320,011 susceptible birds.
Feb 9 OIE report on H5N8 in Germany's Bradenburg state
Feb 9 OIE report on H5N8 in Germany's Mecklenburg-Vorpommern state
Feb 10 OIE report on H5N8 in the Ukraine
Feb 10 OIE report on H5N8 in Poland
Feb 10 OIE report on H5N8 in Poland
Feb 10 OIE report on H5N8 in Latvia
Feb 9 OIE report on H5 in Bulgaria

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