News Scan for Aug 16, 2022

Respirator use and COVID-19
US Omicron BA.5 increase

Healthcare workers wearing respirators 40% less likely to contract COVID

A study of more than 2,900 healthcare workers (HCWs) shows that those who wore a respirator were more than 40% less likely to be infected with COVID-19 than those wearing a surgical mask.

In the study, published yesterday in JAMA Network Open, researchers evaluated SARS-CoV-2 infection rates and cumulative COVID-19 patient exposures among 2,919 HCWs at seven healthcare networks in Switzerland from September 2020 to September 2021, before the Omicron variant became widespread.

At the end of the study, the team asked participants whether they had worn FFP2 respirators (similar to N95 respirators in the United States) or surgical masks during contact with COVID-19 patients other than during aerosol-generating procedures. To quantify cumulative patient exposures, the researchers multiplied the self-reported number of contacts with COVID-19 patients by average contact duration.

Of the 2,919 HCWs, 749 (26%) tested positive for COVID-19. Among participants with patient exposure, test positivity was 21% for those wearing a respirator, compared with 35% in those using surgical masks or a mix of masks (odds ratio [OR], 0.49).

Risk factors for COVID-19 infection included an infected household member (OR, 7.79) and exposure to patients (OR, 1.20 per category of cumulative contact), while respirator use (OR, 0.56) and vaccination (OR, 0.55) were protective.

"SARS-CoV-2 positivity in HCWs was associated with cumulative COVID-19 patient exposure," the researchers wrote. "The odds of being SARS-CoV-2–positive were reduced by more than 40% in individuals using respirators irrespective of cumulative exposure, even after adjusting for multiple work- and nonwork-related covariables."

The authors said that the data suggest a dose-response relationship between exposure to COVID-19 patients and the risk of infection. "Consequent use of respirators and SARS-CoV-2 vaccination might substantially decrease the work-related risk for HCWs exposed to patients with COVID-19," they wrote. "Whether these results are applicable to newer viral variants, which are more contagious and less neutralized by most vaccines, remains to be seen."
Aug 15 JAMA Netw Open research letter


Omicron subvariant BA.5 now makes up 89% of US COVID-19 infections

The highly transmissible Omicron subvariant BA.5 now causes almost 90% of US COVID-19 cases, and First Lady Jill Biden has tested positive for the disease but has mild symptoms.

The Centers for Disease Control and Prevention's (CDC's) Nowcast variant tracker estimates that BA.5 now accounts for 88.8% of new US COVID-19 cases, while BA.4 accounts for 5.3% and BA.4.6 accounts for 5.1% of new cases. Four weeks ago BA.5 made up 74.0% of COVID-19 cases, and 2 weeks ago it accounted for 84.5%.

Jill Biden's COVID-19 symptoms so far remain mild, the White House announced today, according to the Associated Press (AP). President Joe Biden continues to test negative after recovering from COVID.

The 71-year-old first lady began experiencing symptoms late last night after testing positive earlier in the day, the White House said in a statement. Both Jill Biden President Biden have received four doses of the Pfizer COVID vaccine. She has been prescribed Paxlovid and will isolate at the Biden vacation home for at least 5 days. Her close contacts have been notified.

The 7-day average of new daily US COVID-19 cases is 99,832, with 489 daily deaths, according to the New York Times tracker. The HHS Protect Public Data Hub shows that 41,170 inpatient beds and 4,428 ICU beds are in use for COVID-19 across the country. Almost 87,000 child COVID-19 cases were reported for the week ending Aug 11, down from more than 96,000 the previous week, according to the American Academy of Pediatrics.

In other US news, the School District of Philadelphia has mandated that students and staff wear masks for the first 10 days of the school year and pre-kindergartners wear masks all school year, Fox News reports.
CDC Nowcast variant tracker
Aug 16 AP story
Aug 16
White House statement

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