Intubation with closed HEPA filtration
A letter to the BMJ describes a technique for intubating with a HEPA filter already attached to the ETT to reduce aerosolization during intubation and while connecting the circuit. While if the filter is connected in-line to the ETT, a stylet cannot be used, they also describe a technique for connecting a swivel-elbow with a seal port to the ETT to allow a bougie through the seal port.
Successful transmission prevention at four overnight camps
A recent MMWR reported that among 1,022 attendees of four overnight camps in Maine in summer 2020, there was no transmission of COVID-19 identified during camp. The camps employed several interventions to prevent and mitigate viral transmission, including a 10-14 day prearrival quarantine at home, pre- and postarrival testing and symptom screening, cohorting in groups of 5-44 for 14 days after camp arrival, use of masks when interacting with others outside the cohort, physical distancing, enhanced hygiene measures, cleaning and disinfecting, and maximal outdoor programming. Staff and campers were tested prior to arrival and 4 asymptomatic cases were identified; these people delayed their arrival until after they had completed their isolation periods. Staff and campers were retested one week after arrival and 3 asymptomatic cases were found and immediately isolated. Their close contacts were quarantined. All close contacts were tested before ceasing quarantine and results were negative. These results support the efficacy of a multilayered approach to transmission prevention and efficacy.
Bus transmission
A report from eastern China found that among 300 people attending a 2 ½ hour long mostly outdoor worship event in January 2020 where one person had COVID-19, 22 of the 67 people (32%) who took a bus with the index patient were later diagnosed with COVID-19, while 7 of the 232 others (3%) who attended the event later tested positive. Of the latter, all 7 reported close contact with the index patient. A particularly high risk of infection was seen in passengers sitting within three rows of the index patient, with an attack rate of 42% compared to 27% in more distant rows. The bus had recirculating air conditioning for the duration of the 100 minute round trip, and, importantly, no masks were worn by any passenger. The index patient had recently had dinner with people who had traveled to Wuhan, and was asymptomatic during the bus trip but developed symptoms the evening of the worship event. This analysis suggests that transmission largely occurred on the bus (the indoor enclosed environment with recirculating air) and was likely airborne to some extent, underscoring the importance of masks and good ventilation in preventing COVID-19 transmission.
Why is 6 feet apart the magic distance?
A BMJ editorial discusses literature on respiratory transmission at various distances from other diseases that has been reapplied to COVID-19 as well as the small studies conducted since the pandemic began, and proposes a graded model of transmission risk based on ventilation, population density, masking, duration of contact and type of activity. This model underscores the role of good ventilation and wearing masks, citing among other sources a preprint from Japan that found a more than 18-fold increase in risk with interactions indoors compared to outdoors. However, since transmission risk at a 3 foot distance is estimated to be 2-10 times higher than at a 6 foot distance on average, 6 feet is a good rule of thumb and a reasonable starting point for public education. Clinicians may also want to encourage patients to avoid indoor gatherings whenever possible.
Pilot RCT of vitamin D supplementation in hospitalized patients
A pre-proof (peer-reviewed but not yet published) small RCT from Spain accepted by a biochemistry journal reports that of 76 consecutively admitted adults with COVID-19, the cohort of 50 randomized to oral calcefediol had 1 ICU admit and no deaths while the 26 who received no calcefediol had 13 ICU admits and 2 deaths. The study was performed in an area that had previously demonstrated significant rates of vitamin D deficiency. There were several major limitations to this study, among them that the trial was randomized but not blinded, all patients received hydroxychloroquine and azithromycin and a more seriously ill cohort (number not given) also received ceftriaxone, the day of illness at admission is unclear, they did not track obesity (now understood to be a major contributor to the risk of severe illness), it is not clear if any patients received steroids and the randomization did not result in well-balanced groups. For example, the control cohort was 69% male compared to a 54% male intervention group, the average D dimer was twice as high in the control group, and rates of hypertension and diabetes were higher in the control group. Authors did not report vitamin D levels in patients in this study, although other studies have hypothesized that patients with low vitamin D levels may be at an increased risk of COVID-19 infection. Low vitamin D levels are also linked with an increased all-cause risk for ICU admission, although high-dose supplementation in the ICU does not seem to confer a benefit.
A larger multi-center study is planned on the basis of the results of this pilot study, and authors note that they now consider the use of glucocorticoids in hypoxemic patients standard of care, while hydroxychloroquine-azithromycin is no longer used.
COVID Vaccine ECHO
The COVID Vaccine ECHO is scheduled to begin next Wednesday, September 9th from 3-4pm. It will occur on the 2nd and 4th Wednesdays of the month. The registration link is below: https://echo.zoom.us/meeting/register/tJAufuqqqz0pEtxIsd6tK_4pcTFwKCGCxoRB. The target audience is emergency managers, immunizations coordinators/teams and clinical/community partners. Please help spread the word!
Notes on a previous clinical update
A previous clinical update discussed a methods paper that tested fabric types used in cloth masks. One surprising result of that small paper was that they found increased droplet penetration through fabric used for neck gaiters. Since then, another experiment was conducted using OSHA’s typical methods for mask assessment, involving testing the entire neck gaiter using nebulized droplets, and found it was comparable to other forms of cloth masks tested.
The originally reported methods paper, as with many COVID-19 related science currently being published or submitted for publication (including the experiment linked above), is a small study carrying many limitations. As a New York Times article notes, the media attention the original study received may have unintended consequences such as public or peer shaming over wearing neck gaiters as masks, detracting from the overall goal of universal masking.
Another source of summarized literature
Last week, the CDC Office of Library Science began a series of summary updates of scientific literature, covering a wide range of topics related to COVID-19 and aimed at public health professionals. The summaries are available in full on the CDC COVID-19 Science Update website and selected articles of clinical relevance will be reviewed here as well.
