Researchers report 21% COVID-19 co-infection rate

A research letter published yesterday in JAMA found that rates of COVID-19 co-infections with other respiratory pathogens are 21%, higher than previously thought, suggesting that identification of another pathogen may not rule out the presence of the novel coronavirus.

Also, a letter yesterday in the Annals of Internal Medicine detailing survey results on 272 primary care physicians in Lombardy, Italy, who cared for about 400,000 COVID-19 patients found that 40% had symptoms suggestive of the disease, and most had to buy their own personal protective equipment (PPE) and educate themselves on coronavirus management.

Co-infection rate higher than thought

Early in the pandemic, reports from China indicated that co-infection of COVID-19 and other respiratory pathogens was uncommon, suggesting that patients who tested positive for other pathogens could be assumed to not have the novel coronavirus.

Also, the US Centers for Disease Control and Prevention recommended testing for other respiratory pathogens, saying that confirmation could help rule out COVID-19 amid the lack of widely available testing.

In the JAMA letter, Stanford University researchers performed real-time reverse transcriptase-polymerase chain reaction for COVID-19 and other respiratory pathogens on nose and throat swabs from 1,206 symptomatic patients from multiple sites in northern California from Mar 3 to 25.

Some sites tested the specimens for COVID-19 as well as influenza A and B, respiratory syncytial virus (RSV), non–COVID-19 coronaviruses, adenovirus, parainfluenza 1 through 4, human metapneumovirus, rhinovirus/enterovirus, Chlamydia pneumoniae, and Mycoplasma pneumoniae.

They found that, of the 116 specimens that tested positive for COVID-19, 24 (20.7%) were positive for at least one other pathogen, versus 294 of the 1,101 specimens (26.7%) negative for the novel coronavirus (difference, 6.0 percentage points [95% confidence interval (CI), –2.3 to 14.3]).

The most common co-infections included rhinovirus/enterovirus (6.9%), RSV (5.2%), and non–COVID-19 coronaviruses (4.3%). None of the differences in rates of non–COVID-19 pathogens between specimens positive and negative for the novel coronavirus was statistically significant (P < .05).

Of 318 samples positive for at least one pathogen that was not SARS-CoV-2, the virus that causes COVID-19, 24 (7.5%) were also positive for the novel coronavirus. Of 899 samples negative for other pathogens, 92 (10.2%) were positive for SARS-CoV-2 (difference, 2.7 percentage points [95% CI, –1.0 to 6.4]).

"These results suggest that routine testing for non–SARS-CoV-2 respiratory pathogens during the COVID-19 pandemic is unlikely to provide clinical benefit unless a positive result would change disease management (eg, neuraminidase inhibitors for influenza in appropriate patients)," the authors said.

Unprepared, unprotected doctors in Italy

In the Annals of Internal Medicine letter, researchers from Humanitas University in Milan, Italy, describe how hospital overcrowding and inadequate PPE and training put healthcare workers—particularly frontline general practitioners (GPs)—at high risk for COVID-19. As of Apr 8, more than 6,000 Italian medical workers had been infected, and 94 physicians had died, including more than 20 GPs in Lombardy.

Of the 272 GPs responding to the survey, 108 (38.7%) reported having symptoms of COVID-19 during January to March. Fifty-four (50.0%) had respiratory symptoms, 54 (50.0%) had gastrointestinal symptoms, and 31 (28.7%) had both.

Of those with gastrointestinal symptoms, 77.8% had diarrhea for 3 days or less, and about half of those with respiratory symptoms said their symptoms lasted at least 7 days.

Only 18 (6.6%) had a throat swab taken to test for COVID-19, half of them because they had symptoms (8.3% of all 108 symptomatic GPs). Only 2 swabs were positive, 1 in a GP with respiratory symptoms and 1 with only diarrhea.

Of the GPs, 125 (46.0%) had one or more contacts with a patient with confirmed COVID-19, and 76.0% of the patients they referred to the hospital with symptoms suggestive of the novel coronavirus were positive for it. In response to the pandemic, 238 GPs (87.5%) changed how they delivered patient care, with 73.1% doing so via phone calls, 24.4% with telemedicine, and 2.1% with other methods.

The vast majority (264 [97.1%]) adopted ways to avoid patient overcrowding at their clinic. Only 46% said that their local health department gave them PPE, including surgical masks (94.4%), gloves (92.0%), disposable respirators (16.0%), and hand sanitizer (33.6%). Most (84.6%) had to buy their own PPE, and only 18.4% could give PPE to patients in their waiting rooms.

Only 85 GPs (31.3%) received training on COVID-19 management, 67.1% through online sources and 32.9% through courses or meetings. Of the GPs, 3.5% received the training in January, 44.7% in February, and 51.8% in March. The other 187 GPs prepared themselves, 48.7% with medical journals, 28.9% with online courses, 11.8% with leaflets and newsletters from the Ministry of Health or local health departments, and 10.6% through the mass media.

One-third said that the PPE given to them was insufficient, 12.0% that the training was inadequate, 7.0% that diagnostic tests should be more available, and 18.0% that communication and coordination with health departments and institutions need improvement.

The study "provides early insight into the urgent need to test and isolate at least symptomatic GPs to prevent community spread, provide necessary and adequate PPE to all GPs to protect them from COVID-19 during their daily work, and educate GPs and provide clear guidance on how to manage patients during the COVID-19 outbreak," the authors wrote.

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