COVID-19 Scan for Dec 21, 2020

Excess pandemic deaths
COVID-19 in pigs

Higher pandemic death rate found in Hispanics, older adults, less educated

A study of pandemic deaths in California in JAMA Internal Medicine today found the highest excess mortality in older adults, black and Hispanic residents, and those without college degrees. Excess death rates for Hispanic residents and those without a high school degree more than tripled after reopening, likely due to increased COVID-19 risk faced by low-wage, essential workers.

Researchers evaluated mortality data across population subgroups in California from Mar 1 to Aug 22, finding 19,806 deaths in excess of those predicted by historical trends (95% prediction interval, 16,364 to 23,210). California has a population of 39 million, about 12% of the total US population.

Per capita excess mortality was highest among people aged 65 years and older, representing 66.5% of the total excess deaths in the state (13,187 out of 19,806 deaths). Black and Hispanic residents had higher per capita mortality than whites (1,206 and 922 per 1,000,000 people, respectively, vs 485 for whites).

Hispanic residents and those without a high school degree showed the greatest increases in excess deaths when comparing the Mar 1 through May 9 statewide shelter-in-place period versus the May 10 through Aug 22 reopening period. Excess deaths after reopening for Hispanic residents and those without a high school degree were more than triple those observed during the shutdown period (3.1- and 3.4-fold increases, respectively).

"Across age groups, younger adults had the greatest increases in excess death, with rates more than doubling between shutdown and reopening (age, 25-54 years: from 4 to 11 excess deaths per million, 55-64 years: from 12 to 30 excess deaths per million)," the authors wrote.

"We hypothesize that this pattern reflects the risk of COVID-19 death faced by low-wage, essential workers and their social networks owing to occupational exposure, crowded housing, and inadequate access to testing or treatments," they added.

"Our findings underscore the importance of examining the inequitable effects of policies during the pandemic, reexamining the effects over time, and investing in strategies to mitigate the excess mortality in affected communities."
Dec 21 JAMA Intern Med study


Pigs susceptible to SARS-CoV-2, researchers discover

In a study in Emerging Infectious Diseases late last week, Canadian and US researchers found that pigs are susceptible to SARS-CoV-2, the virus that causes COVID-19, highlighting the need for additional livestock assessment to determine the potential role of domestic animals in the pandemic.

Previous studies indicated that swine are not susceptible to SARS-CoV-2 infection, but they did not measure seroconversion (antibody production), the authors note.

They inoculated 19 8-week-old pigs (6 castrated males and 13 females) with an oronasal solution containing the SARS-CoV-2 virus, using a 10-fold higher infectious dose than that used in previous studies.

The researchers performed physical examinations and collected blood, rectal, oral, and nasal samples at the time of inoculation and every other day from day 3 until day 15. They evaluated samples for viral RNA using reverse-transcription polymerase chain reaction (RT-PCR) testing and tested blood serum for neutralizing antibodies. Necropsies and post-mortem sampling started at day 3 after inoculation and continued until day 29.

Starting at day 1, all of the pigs developed mild ocular discharge—accompanied by nasal secretion in some of the animals—which continued through day 3. Animal temperatures remained normal throughout the study, and none of the animals developed clinically observable respiratory distress, but one pig developed a mild cough lasting through day 4.

Among the 16 inoculated animals, 31.3% (5) displayed some level of exposure or an immune response to the virus. Only 1 pig—the animal that developed a mild cough—retained live virus, detected in a post-mortem sample of a lymph node. Two other animals had detectible RNA in a nasal wash sample, and two additional pigs had antibodies in blood serum. Among the five animals with potential infection, only low levels of viral RNA were detected, and no live viral shedding was identified.

Two control pigs were introduced to the infected pigs at day 10 to evaluate potential animal-to-animal transmission, but no viral infection occurred.

The authors conclude, "To date no SARS-CoV-2 cases among domestic livestock have been documented by natural infection; however, the results of this study support further investigations into the role that animals might play in the maintenance and spread of SARS-CoV-2."
Dec 18 Emerg Infect Dis study
Nov 17 CIDRAP News scan on COVID-19 in poultry

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