Sensitivity of home COVID rapid antigen tests peaks 4 days after illness onset

The sensitivity of home rapid antigen COVID-19 tests peaks 4 days after symptom onset, suggesting that a negative antigen test should be followed by a second test in 1 or 2 days, according to a prospective study published today in JAMA Internal Medicine.

The study, led by the US Centers for Disease Control and Prevention (CDC) COVID-19 Response Team, studied test sensitivity in 225 adults and children from 107 households who tested positive for COVID-19 in San Diego County, California, and metropolitan Denver from January to May 2021.

Participants used antigen tests for 15 days and had at least one same-day reverse-transcription (RT) PCR test and viral culture. A total of 3,044 antigen tests and 642 PCR tests were performed. Average participant age was 29 years, 52% were female, and 91% had COVID-19 symptoms.

Antigen tests were less sensitive than PCR, but more sensitive than viral culture. During the first few days of illness, antigen test sensitivity was 50% (95% confidence interval [CI], 45% to 55%). Overall antigen test sensitivity was 64% (95% CI, 56% to 70%) and 84% (95% CI, 75% to 90%) compared to PCR and viral culture, respectively.

Sensitivity of the antigen tests peaked at 77% (95% CI, 69% to 83%) 4 days after symptom onset and was 81% to 85% on a second test 1 or 2 days later. PCR positivity peaked at 95% 3 days after illness onset, while viral cultures peaked at 64% on day 2. Six days after symptom onset, antigen test positivity was 61% (95% CI, 53% to 68%), falling to less than 20% by day 11.

The researchers noted that antigen test performance may differ in vaccinated and unvaccinated people and among infections with different SARS-CoV-2 variants. The findings, they said, could help optimize the recommended length of isolation after COVID-19 diagnosis.

"These findings support the current CDC recommendation for strict use of face masks in settings with other people and continued isolation from unvaccinated or immunocompromised individuals through 10 days after illness onset," they wrote.
Apr 29 JAMA Intern Med study

Scientists detail clinical picture in Alabama hepatitis cases

Today in Morbidity and Mortality Weekly Report (MMWR) authors describe the clinical findings of nine children in Alabama who developed acute hepatitis. The children also had adenovirus upon hospital admission.

The Alabama cluster was the first hepatitis cluster identified in the United States, after similar patterns of illness have been detected across the United Kingdom, Europe, and Israel. All children were identified after Oct 1, 2021.

The children had no geographical or epidemiological links, and all were age 5 and under.

"Before admission, among the nine patients, vomiting, diarrhea, and upper respiratory symptoms were reported by seven, six, and three patients, respectively," the authors said. "At admission, eight patients had scleral icterus, seven had hepatomegaly, six had jaundice, and one had encephalopathy."

Two children required liver transplants, and adenovirus was detected in all children, with type 41 detected in five specimens.

According to the European Centre for Disease Prevention and Control (ECDC) in its weekly communicable disease update, as of Apr 28, four cases of acute hepatitis have been reported in Wisconsin, seven cases in California, nine cases in Alabama, three in Illinois, two in North Carolina, and one in Delaware.
Apr 29 MMWR study
Apr 29 ECDC report

Senators introduce bill to fund research, management of CWD

Senators have introduced bipartisan legislation to support the research and management of chronic wasting disease (CWD).

The bill, introduced by US Senators Martin Heinrich (D-N.M.) and John Hoeven (R-N.D.) would authorize $70 million per year for CWD research and management to be administered by the US Department of Agriculture through cooperative agreements with state and Tribal wildlife agencies and agriculture departments. A similar bill passed the US House of Representatives in December 2021.

CWD is a prion disease that is always fatal to members of the deer family (cervids) that it infects, and spreads among cervids through direct contact and from infected saliva, urine, and feces of live animals or carcasses and body parts. At least 30 states have reported CWD cases to date. No human cases have been detected yet, but the Centers for Disease Control and Prevention warn people not to eat meat from CWD-infected animals.

The money would be used to develop methods to effectively detect CWD in live cervids and the environment, identify genetic resistance to CWD, create sustainable CWD management practices, and monitor areas with the highest CWD incidence and those showing the greatest risk of an initial occurrence. The legislation would also include an authorization for USDA and state and Tribal agencies to develop educational materials on CWD.

"CWD is a growing threat to both wildlife and livestock, impacting sportsmen, ranchers and the local ecology of regions across the U.S.,” Sen. Hoeven said in a press release. "Our legislation would empower state and tribal governments to better manage and prevent outbreaks of this deadly disease, while also advancing new methods for detecting CWD and limiting its spread."
Apr 28 press release

Clinical trial will examine antibiotic use in treatment of gum disease

The National Institutes of Health this week announced a $2.4 million grant for a clinical trial to study responsible use of antibiotics in the treatment of severe gum disease.

The trial, which will be run by the University of Texas Health Science Center at San Antonio in collaboration with American Dental Association Science & Research Institute, will enroll 1,050 periodontal patients. Clinicians will share clinical and patient-experience data about the efficacy of adjunctive antibiotics, which are commonly used for treatment of periodontitis in conjunction with deep cleaning. To date, data on the benefit of adjunctive antibiotics for periodontitis has been unclear.

"With the current rise of superbugs, which are multi-resistant bacteria that kill tens of thousands of Americans every year due to antibiotic resistance, there is a critical need to determine if specific patient populations benefit from adjunctive antibiotics," principal investigator Georgios Kotsakis, DDS, of the UT Health San Antonio School of Dentistry, said in a press release. "This new trial is expected to have a major impact on reducing antibiotic misuse in dentistry, which contributes to antibiotic resistance." 

The trial is expected to begin in the spring of 2023.
Apr 27 UT Health San Antonio press release

Three countries report more polio cases, GPEI adds more details on Pakistan case

Three countries—the Democratic Republic of Congo (DRC), Nigeria, and Somalia—reported more polio cases this week, all involving circulating vaccine-derived poliovirus type 2 (cVDPV2), according to the latest weekly update from the Global Polio Eradication Initiative (GPEI).

The DRC reported four more cases, three from Maniema province and one from South Kivu province, lifting the country's total for the year to 22. Nigeria reported one more case, which was from Bauchi state, bringing its 2022 total to 17. Also, Somalia reported one case, from Lower Shabelle, marking its second case of the year.
Also, the GPEI fleshed out more information about Pakistan's recent wild poliovirus type 1 (WPV1) case, which was reported by the country's health ministry last week and is only the third WPV1 case reported so far this year.  The case was Pakistan's first since January 2021.

It said the virus is linked to an environmental sample collected on Apr 5 from North Waziristan, the same area the boy lives. The GPEI said such low-level transmission isn't surprising at this stage of Pakistan's polio eradication efforts. The country is seeing record-low levels of WPV1 transmission, and similar low-level activity was seen during the "end game" for WPV1 in other countries, including Nigeria, India, and Egypt.
Apr 28 GPEI update
Apr 22 CIDRAP News scan