News Scan for Jul 26, 2021

COVID-19 in college roommates
COVID vaccine for kidney recipients
Interspecies CWD spread
Saudi MERS case
More H5N6 avian flu cases in China

COVID in dorms led to roommate transmission 20% of the time, study says

Out of 574 multiple-occupancy dorm rooms, roommate transmissions occurred only 20% of the time, according to a study during the fall 2020 semester at the University of Colorado Boulder.

The study, published late last week in The Journal of Infectious Diseases, looked at 6,408 dormitory students at the University of Colorado Boulder who were subject to a mandatory weekly COVID-19 test. From Aug 24 to Nov 25, 2020, 16.5% tested positive, with most asymptomatic at the time of testing. Case investigations and contact tracing showed that many cases originated off campus.

Cases occurred more in multiple-occupancy rooms than single rooms (19.1% vs 10.3%), but the researchers note that multiple-occupancy rooms were 70% of all rooms in the study. Of the 574 multiple-occupancy rooms with at least one positive student and an adequate testing record, 7.7% had multiple positive cases at the same time indicating independent exposure, 20.2% had likely in-room transmissions (up to 14 days after index patient test), and 72.1% had no roommate transmissions.

The researchers add that people who did transmit the virus had viral loads about 6.5 times higher than those who did not (26.2 vs 28.9 average cycle threshold value).

While more students in singles moved into isolation rooms the day of their positive diagnosis than those in a multi-person room (18.6% vs 9.6%), its association was insignificant (odds ratio, 1.16). The odds of transmission for cycle threshold value, however, was significant and independent, with a 14% reduction of transmission odds for every additional cycle threshold.

"Thus, roommate-to-roommate transmission is not the primary reason that positive cases occurred nearly twice as frequently among students in multiple-occupancy rooms compared to singles," the researchers conclude.
Jul 24 J Infect Dis study


Third COVID vaccination spurred antibodies in some kidney recipients

Almost half of kidney transplant recipients who received a third COVID-19 vaccination dose by Moderna were able to reach adequate antibody levels, according to a research letter late last week in JAMA.

Everyone in the cohort had produced less than 50 arbitrary units per milliliter (AU/mL) or no antibodies 1 month after their second Moderna vaccine (40.3% and 59.7%, respectively). Most (61.6%) were men, and the median age was 57.6 years. They received their kidneys a median of 5.3 years ago, and all were outpatients of the Strasbourg University Hospital in France.

From Apr 9 and May 12, a third dose was given a median of 51 days after the patient's second dose. Twenty-eight days later, almost half (49%) had antibody levels greater than 50 AU/mL (median, 586 AU/mL). Adequate antibody levels were more likely to occur if the patient had a weak antibody response versus no antibody response after the second dose (81.3% vs 27.4%). Those taking tacrolimus, mycophenolate, and steroids, however, showed less sufficient antibody levels (35% vs 63%).

Overall, 51% of patients did not develop 50 AU/mL of antibodies after the third dose, although the researchers add that B- and T-cells were not studied.

"The possibility that patients developed cellular immunity capable of conferring protection against severe disease was not assessed. However, the occurrence of severe COVID-19 in some vaccinated transplant recipients may suggest a lack of immunity," the researchers write.
Jul 23 JAMA study


CWD prions have different interspecies transmission risks, study says

Norwegian chronic wasting disease (CWD) prions have a higher potential to infect other animals, but North American CWD prions may generate more human prions, according to a Journal of Infectious Diseases study late last week.

CWD is a fatal prion disease affecting the cervid family (eg, deer) that is spread through contact with contaminated body fluids, shed antler velvet, and environmental contamination.

The researchers used Protein Misfolding Cyclic Amplification (PCMA) technology to measure in vitro conversion of normal prion protein in mice, hamsters, sheep, cattle, pigs, and humans after exposure to CWD prion proteins from six cervids. Three of the cervids had the North American CWD prion (white-tailed deer, mule deer, and elk), and the other three were infected with the Norwegian CWD prion (reindeer, red deer, and moose).

Prepping the CWD prion samples involved normalizing protein quantity via dilution after digesting cervid brain material with proteinase K. Afterward, the researchers induced protein conversion in various animal species and made radar plots marking the last dilution of CWD solution that was able to generate CWD proteins in the measured species.

"In general terms, Norway CWD appeared more prone to cross species barriers than North American isolates, except for white-tailed deer that seemed also highly transmissible. We estimated a spillover potential index to evaluate quantitatively the differences on transmission potential among distinct CWD prions. Using this approach we found that the index was reindeer > moose = white-tailed deer > red deer > mule deer > elk," write the researchers.

"Conversely, none of the three Norway CWD isolates generated any detectable [prion protein] signal up to the second round of PMCA. This data suggest that North American CWD prions might be of a greater risk to humans than the infected animals in Northern Europe," the authors continue, noting that white-tailed deer showed the most conversion, followed by mule deer then elk.

"We speculate that these differences might be due to Norwegian CWD being less stable prion strains as compared to North American CWD, which have had longer time to replicate in cervids and become stabilized through many rounds of natural infection," they write.
Jul 24 J Infect Dis study


Saudi Arabia reports first MERS case since early June

Saudi Arabia has reported a new MERS-CoV (Middle East respiratory syndrome coronavirus) case, the country's first since early June.

In a report, the Ministry of Health (MOH) said the patient is a 67-year-old man from Riyadh who had contact with camels. Contact with camels, including drinking camel milk, is one of the leading causes of MERS transmission. The man is not a health worker, and his infections is listed as active.

This is the country's tenth case of MERS detected this year. The World Health Organization said in an update earlier this summer that it has received reports of 2,574 cases, at least 886 fatal, since the first human infections were detected in 2012. The vast majority are from Saudi Arabia.
Jul 21 Saudi MOH notice


H5N6 avian flu infects 3 more in China, 1 fatally

China's mainland has reported three more H5N6 avian flu cases, one of them fatal, all involving adults who had contact with poultry, Hong Kong's Centre for Health Protection (CHP) said in a recent statement.

Two of the patients are from Sichuan province in the southwest, including a 51-year-old woman from Xuanhan who had contact with domestic poultry before her symptoms began on Jun 25. She was admitted to the hospital on Jul 2 and died on Jul 4. The other Sichuan province patient is a 57-year-old man from Kaijiang who also had contact with domestic poultry before he got sick on Jun 22. He was hospitalized on Jul 5 and is listed as being in critical condition.

The third patient is from Tongnan in the south-central Chongqing municipality. He had contact with domestic poultry before his symptoms started on Jun 23. On Jun 30 he was hospitalized, where he is in critical condition.

China has now reported 11 H5N6 infections for the year and has tallied 35 cases since the virus was first identified in humans in 2014.

Though H5N6 is known to circulate in poultry in a handful of Asian countries, so far only China and Laos have reported human cases. The human infections involving the strain are often severe or fatal.
Jul 23 CHP statement

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