COVID-19 Scan for Mar 11, 2021

News brief

mRNA COVID vaccination tied to 80% lower risk of asymptomatic infection

A real-world Mayo Clinic study shows a link between vaccination with two doses of an mRNA-based COVID-19 vaccine—either Pfizer/BioNTech or Moderna—and an 80% lower risk of asymptomatic infection.

The retrospective cohort study, published yesterday in Clinical Infectious Diseases, involved 39,156 asymptomatic adult COVID-19 patients screened for SARS-CoV-2 infection using 48,333 preprocedural tests from Dec 17, 2020, to Feb 8, 2021.

Forty-two (1.4%) of 3,006 tests of patients who had received at least one dose of vaccine were positive for COVID-19, compared with 1,463 (3.2%) of 45,327 tests of unvaccinated patients (relative risk [RR], 0.44).

Compared with unvaccinated patients, the risk of asymptomatic COVID-19 was lower among those who had received one dose of vaccine at least 10 days before testing (72% reduction; RR, 0.21) and those who received a second dose (73%; RR, 0.20). But after adjustment for confounding factors, the risk of infection was 80% lower in those who received two doses.

"The results of this study demonstrate the impact of the vaccines on reduction in asymptomatic infections supplementing the randomized trial results on symptomatic patients," the researchers wrote. "From a public health perspective, it will be important to determine if the current recommendations to maintain pre-vaccination behaviors for masking and social distancing will impact vaccine hesitancy."
Mar 10 Clin Infect Dis study


Increasing age associated with symptomatic COVID-19 after close contact

A new study out of Italy's hardest-hit region early in the pandemic shows that children and young adults developed symptoms at a far lesser rate than older case contacts after exposure to a COVID-19 case. The study was published yesterday in JAMA Network Open.

The findings were based on 5,484 quarantined close contacts of confirmed cases in the Lombardy region. Half of the close contacts (2,824, or 51.5%) tested positive for COVID-19, but most did not develop respiratory symptoms or fever: Only 26.1% (95% CI, 24.1%-28.2%) of infected individuals younger than 60 years developed respiratory symptoms or fever, the authors wrote. Among infected participants older than 60 years, 6.6% (95% CI, 5.1%-8.3%) developed critical disease.

Only 18.1% of case contacts under the age of 20 developed symptoms, compared with 64.6% of case contacts over the age of 80. The authors also found some difference between male and female close contacts.

"No significant differences between SARS-CoV-2–infected female and male patients were found in the risk of developing symptoms, whereas female patients were 52.7% (95% CI, 24.4-70.7) less likely to experience critical disease than male patients," the authors wrote.
Mar 10 JAMA Netw Open


Study highlights COVID spread in hospitals despite use of masks, goggles

Harvard University scientists detail three cases of COVID-19 spread despite the use of medical masks and eye protection in a study today in Clinical Infectious Diseases.

The Massachusetts Department of Public Health sequenced the genomes of SARS-CoV-2 specimens from patients and employees at Brigham and Women's Hospital in which spread occurred despite one or both parties wearing ASTM Level 1 masks with ear loops. These masks are designed to filter 95% of bacteria and 0.1-micrometer particles.

Three cases of viral transmission despite use of masks occurred from November 2020 to mid-January 2021, as determined by matching virus genomes. The first involved an asymptomatic, unmasked 82-year-old patient who infected two patient care assistants wearing masks and face shields. Both assistants developed symptoms 4 and 5 days after the patient's diagnosis. One had spent 4 hours with the patient on hospital day 3, and the other tended to the patient for 8 hours on day 4.

The second case involved spread from a presymptomatic masked nurse wearing eye protection to an unmasked 56-year-old patient. The nurse developed COVID-19 symptoms on hospital day 13 from a community contact after having cared for the patient on days 11 to 13.

The third case involved spread from a presymptomatic masked patient to a physician wearing a mask and goggles during a 45-minute encounter at a distance of about 3 feet. The patient developed coronavirus symptoms and tested positive 2 days later, as did the physician on day 4.

The COVID-19 strains involved in the three cases were different from each other and weren't variants of concern.

The authors noted that SARS-CoV-2 is primarily spread through tiny respiratory particles that enter the gaps between masks and faces, particularly during close contact over a prolonged time early in the course of infection. They added that masks may lower infection risk but don't eliminate it.

"These findings teach the importance of not relying on medical masks and eye protection alone to prevent SARS-CoV-2 transmission and beg the question whether respirators should be used more widely when caring for high-risk patients under high-risk conditions in high incidence communities," the researchers concluded.
Mar 11 Clin Infect Dis study

News Scan for Mar 11, 2021

News brief

Higher nursing home use of certain antibiotics, COVID therapies noted

US nursing homes saw an increase in prescribing of antibiotics commonly used for respiratory infections during the pandemic, and large number of residents were prescribed drugs being evaluated for COVID-19 treatment, according to a study yesterday in Clinical Infectious Diseases.

For the study, researchers with the Centers for Disease Control and Prevention looked at long-term care pharmacy data from 1,944 nursing homes in 48 states, assessing two categories of drugs: antibiotics and drugs that were being investigated for COVID-19 treatment, including hydroxychloroquine, famotidine, and dexamethasone. To account for seasonal variability in antibiotic prescribing and decreased nursing home occupancy during the pandemic, the researchers calculated the monthly prevalence of residents with a prescription dispensed per 1,000 residents from January to October 2020, then calculated the monthly relative percent change from 2019 to 2020.

From March to October 2020, prescribing of azithromycin and hydroxychloroquine per 1,000 residents was higher than 2019, most notably in April, when hydroxychloroquine prescribing was 563% higher (prevalence ratio [PR], 6.63; 95% confidence interval [CI], 5.87 to 7.48) and azithromycin prescribing was 150% higher (PR, 2.50; 95% CI, 2.37 to 2.63). Prescribing of these drugs declined in May 2020, but was still significantly higher than 2019 from July through October 2020. Prescribing of famotidine was 59% higher in April 2020 compared with 2019, while dexamethasone was 303% higher by July 2020.

In addition to azithromycin, prescribing of ceftriaxone was 43% higher in April 2020 versus 2019 and prescribing of doxycycline was 6% higher. Ceftriaxone use remained significantly elevated from May (+22%) through October 2020 (+11%) compared with 2019. But total antibiotic prescribing among nursing home residents was lower from May (-5%) through October 2020 (-4%) compared with 2019.

The study authors say the increases in prescribing of these drugs to nursing home residents without clear benefits are concerning, as they could put residents at greater risk for adverse events. They say further studies linking prescribing data to diagnoses and outcomes are needed to determine how appropriate these prescriptions were and what health impacts they had.
Mar 10 Clin Infect Dis abstract


Pew analysis shows antibiotic development pipeline remains thin

The latest analysis of the antibiotic development pipeline by the Pew Charitable Trusts shows there are still too few antibiotics in development to meet current and anticipated needs.

The analysis shows 43 antibiotics with the potential to treat serious bacterial infections were in clinical development as of December 2020, with 15 in phase 1 clinical trials, 13 in phase 2, 13 in phase 3, and 2 with new drug applications submitted to the Food and Drug Administration (FDA). Historically, only 1 in 5 infectious disease drugs that reach phase 1 studies will receive FDA approval, and roughly 60% of those that reach phase 3 will be approved.

At least 19 of the drugs in clinical development have the potential to treat gram-negative ESKAPE pathogens, which is a critical area of unmet need, and at least 15 have the potential activity against carbapenem-resistant/extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa, which are considered high priority threats by the World Health Organization (WHO). At least 10 of the antibiotics, if approved, could address infections caused by drug-resistant Neisseria gonorrhea and Clostridioides difficile.

Only 10 drugs in the pipeline represent a novel antibiotic class or mechanism of action, according to Pew, and none are active against gram-negative ESKAPE pathogens or WHO critical-threat bacteria.

The analysis also found that only two of the companies with antibiotics in development rank among the top 50 pharmaceutical companies by sales, which is further indication that large pharmaceutical companies are abandoning antibiotic development.
Mar 9 Pew antibiotic pipeline analysis


MERS sickens 2 more in Saudi Arabia

Saudi Arabia's Ministry of Health (MOH) today reported two more MERS-CoV cases, both involving people from Riyadh.

One is a 57-year-old man who had contact with camels, and the other is a 56-year-old woman who didn't have contact with camels or others known to be infected with MERS-CoV (Middle East respiratory syndrome coronavirus). Neither was a healthcare worker.

The cases lift the country's total so far this year to seven.

In its last overview of MERS-CoV, the World Health Organization (WHO) said there have been 2,566 human cases reported since 2012, at least 882 of them fatal.
Mar 11 Saudi MOH update


Avian flu outbreaks strike poultry in Niger and Sweden

In the latest avian flu outbreak developments in poultry, two countries reported highly pathogenic events involving different strains: Niger with H5N1 and Sweden with H5N5, according to notifications from the World Organization for Animal Health (OIE).

In Niger, animal health officials reported H5N1 outbreaks at two locations near the capital of Niamey, one housing exotic Brahma hens and the other a layer farm. The events began on Feb 17 and Feb 25, respectively, and taken together, the virus killed 220 of 28,040 susceptible birds. The outbreaks mark the first appearance of H5N1 in Niger since 2017.

Meanwhile, Sweden reported an H5N5 outbreak at a poultry farm in Trelleborg in the far south. The outbreak began on Mar 2 at a layer farm, killing 3,000 of 18,000 susceptible birds. The country's last H5N5 outbreak in poultry was reported in November.
Mar 10 OIE report on H5N1 in Niger
Mar 10 OIE report on H5N5 in Sweden

This week's top reads