COVID vaccine protects against symptoms 6 weeks after infection, study shows

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US healthcare workers receiving additional vaccine doses during the Omicron period (December 2021 to April 2022) had a 45% lower risk of having symptoms 6 weeks after COVID-19 infection, according to a study today in Open Forum Infectious Diseases.

The study results came from self-reported symptom questionnaires completed 6 weeks after the onset of symptoms, and was a sub-analysis of data collected during the Preventing Emerging Infections through Vaccine Effectiveness Testing Project (Project PREVENT).

In total, the researchers enrolled 2,478 participants, of whom 1,422 (57%) had COVID-19. All participants were fully vaccinated with two doses of COVID-19 vaccine, and 66.3% had received a third, booster dose. All participants reported COVID-19–like symptoms within 14 days of a qualifying test.

The prevalence of symptoms at 6 weeks was 26% (373) in those with COVID-19 and 18% (195) in those without COVID-19. SARS-CoV-2–positive participants had either fever or cough as an initial symptom in 71.9% of cases.

Lower odds of symptoms with recent booster

Among participants who had COVID-19, those who had received an additional COVID-19 vaccine dose had a lower prevalence of any symptoms than those who had not at 6 weeks post-infection (adjusted odds ratio [aOR], 0.55; 95% confidence interval [CI], 0.43 to 0.70).

If the third vaccine dose was administered 16 weeks or less before infection, healthcare providers had lower odds of reporting respiratory symptoms (aOR, 0.69; 95% CI, 0.46 to 0.99), psychiatric symptoms (aOR, 0.68; 95% CI, 0.47 to 0.99), or any symptom (aOR, 0.68; 95% CI, 0.53 to 0.87) than those who received the dose more than 16 weeks earlier.

COVID-19 vaccination might lead to fewer 6-week symptoms among persons with symptomatic infection because of its effect in attenuating the severity of acute illness.

"COVID-19 vaccination might lead to fewer 6-week symptoms among persons with symptomatic infection because of its effect in attenuating the severity of acute illness," the authors concluded.

Study finds little genetic similarity in multidrug-resistant bacteria from pets and their owners

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Chris Dall, MA

A study conducted in Germany suggests the interaction between people and their pets is not a major factor in the spread of multidrug-resistant organisms (MDROs), researchers reported last week in Antimicrobial Resistance & Infection Control.

For the study, researchers at Charite University Hospital in Berlin performed whole-genome sequencing (WGS) and core genome multilocus sequence typing (cgMLST) on 252 human, 53 dog, and 10 cat isolates collected from a larger case-control study that examined MDRO risk factors among MDRO-positive and MDRO-negative patients. The analysis focused on pet owners and their pets. While several studies in recent years have reported the identification of genetically similar MDROs in people and pets living in the same household using WGS, the study authors say cgMLST, which offers greater discriminatory power and more precise strain typing, has rarely been used.

A total of 154 human isolates (24.6% of the 626 pet owners in the larger study) and 62 pet isolates (11.9% of the 514 pets in the larger study) tested positive for MDROs. Of the bacterial species detected in the isolates, five MDROs that were present in people and at least one pet species (methicillin-resistant Staphylococcus aureus [MRSA], vancomycin-resistant Enterococcus [VRE], and multidrug-resistant [MDR] Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae) were selected for comparison to identify potential transmission.

Pets may act as a spillover host

Most of the analyzed isolates showed high genetic diversity, with only minor overlaps between people and pets. Only two human-pet pairs were colonized with MDROs (VRE and MDR E coli), which showed no genetic difference, a finding the study authors say could indicate transmission or acquisition from a common source. In addition, significantly more pet owners than pets were MDRO-positive.

"This suggests that the interaction between humans and their pets appears to play a minor role in the spread of the MDROs," the authors wrote. "Pets might act as spillover hosts rather than reservoirs for MDROs with transmission potential to humans. Yet, the possibility of transmission from a shared source remains."

They add that future studies should include other possible transmission routes and common sources of resistant strains.

Quick takes: More H5N1 in California cows, CDC public health awards, yellow fever in the Americas

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Lisa Schnirring

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today confirmed 6 more H5N1 avian flu outbreaks in California dairy herds, raising the total to 238 across 14 states. California's latest confirmations raise the state's total to 40 affected herds. The outbreaks are centered in the Central Valley. California is the nation's largest milk producer.
The US Centers for Disease Control and Prevention (CDC) today announced more than $176 million in awards to support 48 public health partners, a step to strengthen the nation's public health system. In a statement, the CDC said the funding is part of the National Partners Cooperative Agreement and represents support for the first year of a 5-year cycle. The CDC said the awards boost the ability of the public health workforce to deliver essential services and improve organizational and systems capacity and capability, steps that address health priorities and bolster the US public health infrastructure.
Five countries in the Americas region have confirmed 38 yellow fever cases this year, 19 of them fatal, the Pan American Health Organization (PAHO) said in its latest epidemiologic update. Since the agency's last update in July, 5 cases and 2 deaths were added. Countries reporting cases are Bolivia, Brazil, Colombia, Guyana, and Peru. The hardest-hit country is Peru, where 18 cases and 9 deaths have been confirmed.