Increased COVID-19 testing linked to lower transmission

A Sri Lankan analysis of global COVID-19 intervention measures showed that increased testing had the greatest impact on transmission: a 10-fold increase in the ratio of tests to new cases (TCR) reduced a country's average transmission by 9%. The study authors suggest that intense testing combined with isolation may be the most effective and least costly strategy for controlling COVID-19.

Researchers in yesterday's Health Affairs study compiled online data from 173 countries and territories—accounting for 99% of the world's cases—from March to June when some countries achieved near-elimination of COVID-19.

The researchers analyzed data from the Our World in Data (OWID) repository, the Oxford COVID-19 Government Response Tracker, mobile devices, and other online datasets to quantify the association of reverse-transcription polymerase chain reaction (PCR) testing and other interventions with COVID-19 spread. The researchers used the average reproduction number (R₀)—the number of secondary infections generated by one infected person—to estimate transmissibility of the virus.   

Testing intensity—estimated by TCR—had the greatest effect on COVID-19 transmission and was highly statistically significant (P < 10^-16). TCR had a logarithmic impact—a 10-fold increase in TCR reduced the R₀ by 8.6% (95% confidence interval [CI]; 6.8% to 10.3%) and a 100-fold increase reduced the R₀ by 6.4% (95% CI; 13.1% to 19.6%). None of the other intervention measures showed a statistically significant reduction in transmissibility.

"Around half or more of COVID-19 transmission is caused by people who are asymptomatic or who have only minor symptoms, so only increases in PCR testing make it possible to increase detection and isolation of infectious cases, and then to increase the numbers of their potentially infectious contacts who are isolated," the study authors wrote.

"Given the costs and uncertainties associated with other [non-pharmaceutical interventions], a strategy that relies much more on increased testing and isolation deserves serious consideration and resource allocation," the authors concluded.
Dec 2 Health Aff study
Dec 2 Health Affairs news release

COVID-19 may have worsened US overdose crisis

A JAMA Psychiatry study today describes a large national surge in overdose-related cardiac arrest during the initial months of the COVID-19 pandemic in the United States. The study authors suggest that fallout from the pandemic—especially social isolation—may be accelerating a two-decade-long overdose crisis that caused more than 70,000 deaths in 2019 alone, and that measures to address the pandemic have largely failed to mitigate overdose risk.

Researchers analyzed near-real-time data from 25.9 million Emergency Medical Services (EMS) activations in the National EMS Information System (NEMSIS) registry, correlating information with social mobility cell phone data. NEMSIS data include more than 10,000 EMS agencies in 47 states and represents more than 80% of annual EMS activations.

The researchers found that overdose-related cardiac arrests rose sharply in April and corresponded with a steep drop in mobility, reaching 74.1 per 100,000 EMS activations by May 4, more than double the rates from 2018 and 2019 (123.4% above baseline). Rates subsequently decreased but remained elevated, reaching 48.7 per 100,000 activations by Jul 27 (53.7% above baseline). Overall 2020 values for overdose-related cardiac arrests were elevated by approximately 50%.

"Many of the trends predicted by public health experts at the outset of the pandemic, such as an increased proportion of individuals using substances alone, increased toxification of the drug supply, and reduced access to treatment, could increase the lethality of each overdose incident," the authors wrote.

Richard A. Jorgensen, MD, DuPage County coroner in Wheaton, Illinois, said in MedPage Today that the study was consistent with observed increases in overdose deaths in his region. "It became obvious that these are people [for whom] the shelter-in-place is mentally destroying them," Jorgensen said. "If you think about rehabilitation programs that are successful, virtually every one of them relies on societal help."

The study authors advocate for investments in substance use treatment and prevention as core elements of COVID-19 response to mitigate the dramatic increase in overdose rates.
Dec 3 JAMA Psychiatry study
Dec 3 MedPage Today story

Report details 74-case nightclub "superspreader" event

A report in Emerging Infectious Diseases yesterday detailed a 74-case COVID-19 outbreak at a German nightclub in March, highlighting the potential for "superspreader" events and the importance of closures for establishments that involve large social gatherings indoors.

The basement-level Berlin nightclub held events attended by around 300 guests on Feb 29, 150 guests on Mar 2, and 200 guests on Mar 5. Mandatory case notification from laboratories to local health authorities—under Germany's Protection against Infection Act—led to the detection of a positive club-associated case on Mar 6, and the club was closed indefinitely.

Researchers used public data to identify people who had laboratory-confirmed nightclub-associated SARS-CoV-2 infection, and gathered demographic data and information about exposure, symptoms, travel history, and symptom onset from interviews with 44 attendees and 16 staff members. They conducted whole-genome viral sequencing of 17 patient samples to look for differences in viral strains and to assess transmission pathways between infected individuals.

The researchers linked 74 reported cases to the nightclub, with a median age of 30 years and equal numbers of men and women.

Genome sequencing data did not find significant differences that would suggest multiple individuals as the source of the outbreak. One guest self-reported initial symptoms 1 day before attending the Feb 29 event and could be a potential source of the outbreak, but the most probable source for transmission was a staff member who worked at events on Feb 29 and Mar 5 and developed symptoms on Mar 4, the authors suggested. Conclusions about staff transmission are limited, however, by the lack of sequencing data for all reported cases.

The attack rate was particularly high among staff (56%), suggesting a high risk of infection for these workers. "Once ease of restrictions is considered, our study suggests that infection protection should be targeted particularly toward staff in nightclubs and bars," the authors wrote.
Dec 2 Emerg Infect Dis study