A case-series investigation of more than 44,000 COVID-19 patients in Tokyo in 2020 reveals that SARS-CoV-2 transmission events in healthcare and nightlife settings (eg, bars and nightclubs) were most likely to involve at least five infections, with nightlife cases more likely to generate further spread.

A team led by researchers at Tohoku University Graduate School of Medicine in Japan analyzed epidemiologic data from 44,054 COVID-19 patients from Jan 23 to Dec 5, 2020, before vaccines were available. The research was published late last week in JAMA Network Open.

The authors noted that while Japan advised people to stay home and avoid unnecessary travel, the country didn't impose mandatory lockdowns. Rather, the government recommended closures of targeted businesses and limiting business hours and alcohol sales.

Death rate highest in healthcare settings

The researchers focused on seven transmission settings: imported, nightlife, dining, workplace, household, healthcare, and other. The team identified the likely setting for 13,122 infections, including 6,768 households, 2,733 healthcare, and 1,174 nightlife cases.

The first cases appeared in nightlife settings, followed by household and healthcare. Of the more than 6,000 transmission settings, nightlife (18.9%) and healthcare (36.2%) were more likely than dining, workplace, household, and other settings to involve five or more cases.

After adjusting for transmission setting, sex, age group, symptom status, and pandemic wave, the authors found that household and healthcare infections were less likely than nightlife cases to generate further spread (household adjusted odds ratio [aOR], 0.03; healthcare aOR, 0.57).

Of the 30,932 infected patients with unidentified transmission settings, those who had visited nightlife establishments were more likely than others to spread the virus to nonhousehold settings (aOR, 5.30).

The case-fatality rate was highest in healthcare settings (9.8%), with all deaths occurring among patients and visitors. Other risk factors for death were male sex (aOR, 1.90) and age 65 years or older (aOR, 39.85).

"Surveillance and interventions targeting nightlife settings should be prioritized to disrupt COVID-19 transmission, especially in the early stage of an epidemic," the researchers wrote.

Medical technology company Lucira Health, Inc, of Emeryville, California, announced today that the US Food and Drug Administration (FDA) has granted its dual test for COVID-19 and influenza emergency use authorization (EUA).

The company, however, recently filed for bankruptcy, citing the prolonged FDA authorization process.

The Lucira COVID-19 & Flu Home Test is approved for over-the-counter (non-prescription) use at home and for other non-laboratory sites. The company said the molecular test performed similarly for COVID-19 and influenza A and B as polymerase chain reaction (PCR) tests in clinical trials. It is the first at-home COVID and flu test to be granted an EUA and the first approved at-home flu test.

It is a nucleic acid amplification test that uses the same technology as both of Lucira's commercialized FDA-authorized COVID-19 tests. It fits in the palm of a person's hand, assesses nasal swabs, and runs on two AA batteries. USA Today says it costs about $70 in Canada, and Lucira will announce a US price tag in the future.

"Having an at-home molecular test now available should really help people know how to keep their families safe and seek appropriate treatment when they're ill," Davey Smith, MD, head of the Division of Infectious Disease and Global Public Health at the University of California–San Diego, said in the Lucira news release.

"We regret that we had no option but to file for Chapter 11 bankruptcy and that this occurred days before we received regulatory authorization," said Lucira CEO Erik Engelson, MBA, MS. "Unfortunately we were unable to bridge what became a protracted authorization cycle time... The Lucira COVID-19 & Flu Home Test would have been especially useful during the recent, severe respiratory season, and we had produced inventory for an anticipated autumn 2022 launch."

Lucira is seeking a strategic or financial partner to resume manufacturing and development of additional home diagnostic tests.

The World Health Organization (WHO) on Feb 25 shared the latest investigation details about a Marburg virus outbreak in Equatorial Guinea—the country's first—that officials announced earlier this month.

The investigation was triggered after at least eight deaths occurred between Jan 7 and Feb 7 in people from two villages in the same district who experienced hemorrhagic fever. Blood samples collected from eight of their contacts were negative for Ebola and Marburg viruses. Of samples collected for eight additional contacts, one was positive for Marburg, from a patient who died on Feb 10 at a district hospital.

The patient was a contact of four of the people who had died earlier from similar symptoms.

So far, the outbreak total remains at nine cases, including the confirmed case, four probable cases, and four classified as suspected. All cases were fatal. The patient with the lab-confirmed infection was the only one who died in a hospital—the rest died in community settings, a factor known to pose a high risk of further disease spread.

The WHO said all nine patients had contact with a relative who had similar symptoms or had participated in a burial of a patient with similar symptoms, another practice known to enhance the transmission risk.

The WHO said the risk to Equatorial Guinea is high, and it put the risk to the region as medium. The risk is low at the global level.

Marburg virus, a close relative of Ebola, spreads through contact with infected body fluids of infected people. It has a case-fatality rate as high as 88%, and so far there are no approved vaccines or specific treatments.