75% of COVID patients tested positive, 35% had positive cultures, on day 6
Three quarters of a group of nonhospitalized men and women newly diagnosed as having COVID-19 continued to have positive rapid antigen test (RAT) results—and over one-third still had viable virus on culture—6 days later, according to a study led by Brigham and Women's researchers.
If confirmed, the findings, published yesterday in JAMA Network Open, challenge current US Centers for Disease Control and Prevention (CDC) COVID-19 guidelines stating that infected people with healthy immune systems can end isolation after 5 days if they have no symptoms or have improving symptoms and no fever.
The authors noted that culturable virus is currently the best proxy for infectiousness and that RATs correlate with culture positivity early in COVID-19, although little is known about whether they continue to do so after day 5.
From Jan 5 to Feb 11, 2022, 40 COVID-19 patients were enrolled. Average patient age was 34 years, and 90.0% had completed a primary COVID-19 vaccine series and one booster dose. The dominant variant in Boston at that time was Omicron BA.1.
Patients completed daily symptom logs and RATs. On day 6, the researchers obtained samples for viral culture from 17 patients (42.5%). Ten patients (25.0%) tested negative on RAT on day 6, and all patients tested negative by day 14. Average time to first negative RAT in the seven asymptomatic patients was 8.1 days, versus 9.3 in the 33 symptomatic patients. Sixty-one of 90 RATs (68%) from asymptomatic patients were still positive on days 6 to 14.
Of the 17 patients with viral cultures, 12 also tested positive on RAT. Six of the 12 had positive viral cultures, with two each reporting improving symptoms, unchanged symptoms, and never having symptoms. No patient with a negative RAT on day 6 had a positive culture.
"A universal requirement of a negative RAT result may unduly extend isolation for those who are no longer infectious," the researchers wrote. "Meanwhile, a recommendation to end isolation based solely on the presence of improving symptoms risks releasing culture-positive, potentially infectious individuals prematurely."
Aug 3 JAMA Netw Open research letter
Study: Personal care and service workers have highest COVID-19 rates
A new study on occupation and COVID-19 infection in Wisconsin residents shows that personal care and service workers had the highest rates of infection (22.4 per 100 full-time equivalents) followed by healthcare practitioners and support staff (20.7) from September 2020 to May 2021. The study was published today in Clinical Infectious Diseases.
Following personal care and service workers and healthcare workers were protective services workers, who were infected at a rate of 20.7 per 100 full-time equivalents.
The study was based on interviews with 418,935 case-patients meeting eligibility criteria; 375,930 (90%) had confirmed and 43,005(10%) had probable COVID-19 cases, as reported to Wisconsin public health officials. All case-patients were between the ages of 18 and 64.
According to the study, the highest incidence by industry was healthcare (18.6), and the highest-risk subsectors were nursing care facilities (30.5) and warehousing (28.5).
High-risk subgroups included nursing assistants and personal care aides (28.8), childcare workers (25.8), food and beverage service workers (25.3), personal appearance workers (24.4), and law enforcement workers (24.1).
"Groups at increased risk of workplace exposure to SARS-CoV-2 could benefit from continued efforts to promote COVID-19 vaccination, booster coverage, and other setting-specific mitigation strategies such as mask use, symptom screening, improved ventilation, and testing when indicated by local conditions," the authors concluded.
Aug 4 Clin Infect Dis study
Male reproductive tract inflammation linked to prolonged Zika shedding
In a study designed to understand more about Zika virus persistence in semen, which is known to transmit the virus to sexual partners, researchers found that long-term viral shedding is associated with inflammation of the male reproductive tract (MRT). The findings appear today in an advance issue of the Journal of Infectious Diseases.
A team based at Virginia Tech analyzed the semen of 49 infected men in the Americas to look for immune factors linked to long-term virus shedding and infected cells types. For the study, the team used samples collected for an earlier study on virus shedding in semen. Of the group, 26 were identified as long-term shedders, and 23 were identified as short-term.
Prolonged shedding was seen in instances of MRT inflammation, as shown by higher leukocyte counts and inflammatory cytokine concentrations. The researchers also found Zika RNA in seminal leukocytes and epithelial cells.
"Understanding how MRT inflammation is associated with ZIKV [Zika virus] infection will allow for a better understanding of ZIKV sexual transmission, including prediction of shedding length, transmission dynamics, and risk assessments," they wrote. "This knowledge is crucial to reduce ZIKV spread and incidence of congenital ZIKV syndrome."
In a related commentary on the study, Andrew Haddow, PhD, a molecular and cell biologist at Kennesaw State University in Georgia, wrote that more studies are needed to see if preexisting inflammation of the MRT triggers prolonged Zika shedding or if prolonged inflammation after Zika infection leads to prolonged seminal shedding. The treatment of MRT inflammation as a way to reduce Zika shedding also warrants investigation, he said.
Aug 4 J Infect Dis abstract
Aug 4 J Infect Dis commentary
West Virginia reports probable fair-linked H3N2v outbreak
The West Virginia Department of Health and Human Resources (DHHS) yesterday announced that it is investigating several reports of people who got sick with flulike symptoms after working closely with pigs during swine exhibits at the Jackson County Fair.
So far, one specimen from one patient has tested presumptive positive for variant H3N2 (H3N2v). In a statement, DHHS said the sample has been sent to the Centers for Disease Control and Prevention (CDC) for confirmation.
While swine influenza viruses are known to circulate in pigs throughout the year, transmission to humans is relatively rare but can occur, mainly in those who have close contact with the animals. Limited human-to-human spread, though not sustained, has been reported in past years. The viruses are called "variant" when they infect people.
Multiple H3N2v outbreaks in 2012, mainly linked to exposure at fairs, led to 309 cases. Since then, sporadic cases have been reported.
Aug 3 West Virginia DHHS statement