Weekly Update, June 21st to 28th
What is new and important in the world of COVID-19
There have been several notable developments regarding COVD-19 over this past week summarized below. These include
- The expansion of the “at risk” criteria by the CDC
- A warning from the FDA about the accuracy of multiple brands of antibody tests.
- The usefulness of even good antibody tests.
- New information about the survival of SARS-CoV-19 in aerosols.
- Finally, there were two unique ideas were published this week about 1) how to go about testing in low resource areas and 2) how to create an N-95 mask out of a regular surgical mask.
1) The CDC released a new list of individuals at-risk for severe illness with COVID-19. The high-risk criteria include:
- Advanced age
- Chronic kidney disease
- Immunocompromised state
- Obesity (BMI of >30); This is changed from the prior cutoff of a BMI of 40
- “Serious conditions” such as heart failure, CAD, cardiomyopathy
- Diabetes Mellitus type 2
- Sickle cell disease
- Children with congenital heart disease or neurologic or genetic diseases, including inborn errors of metabolism.
A second list of individuals who “might be at increased risk” for severe illness with COVID-19 per the CDC include those with:
- Cerebrovascular disease
- Cystic fibrosis
- Neurologic conditions such as dementia
- Liver disease
- Pulmonary fibrosis
- A significant history of smoking
- Diabetes Mellitus type 1
Pregnancy is a reversal from the previous dictum that COVID-19 risk was not elevated in pregnancy. Additional data on pregnancy now classifies it as a high-risk condition. A CDC study of 8207 patients found that 1) presenting symptoms are the same as in the non-pregnant population, 2) Risk of admission and need for ventilation is increased in those who are pregnant, but mortality rate is not. In this study, 32% of pregnant women were admitted to the hospital compared to 5.2% of non-pregnant women. Part of this may be because of an abundance of caution in treating women who are pregnant, especially since mortality doesn’t differ. None-the-less we know that pregnancy is a relatively immunodeficient state with reduced T4 cells, among other changes.
Ellington S, et.al. Strid P, Tong VT, et al. Characteristics of Women of Reproductive Age with Laboratory-Confirmed SARS-CoV-2 Infection by Pregnancy Status — United States, January 22–June 7, 2020. MMWR Morb Mortal Wkly Rep 2020;69:769–775. DOI: http://dx.doi.org/10.15585/mmwr.mm6925a1external icon.
2) The FDA sent out a warning about the accuracy of multiple brands of antibody tests for COVID. The list is extensive and can be found here under the heading “What Tests Should No Longer Be Distributed for COVID-19?”
We also have additional information from an analysis by the Cochrane group about the clinical usefulness of IgG/IgM tests for SARS-CoV-19. After looking at the literature on enzyme‐linked immunosorbent assays, chemiluminescence immunoassays, and lateral flow assays tests they found that:
Tests were positive:
Only 30% of the time during the first week of illness
72% of the time day 8 of illness to day 14 of illness
92% of the time day 15 to 21
Data beyond 21 days was not considered reliable.
This emphasizes the limited use of these tests in diagnosing acute infection. Nasal swab PCR remains the test of choice.
List of Antibody Tests Withdrawn
Antibody tests for identification of current and past infection with SARS‐CoV‐2 Cochrane Systematic Review -Version published: 25 June 2020 https://doi.org/10.1002/14651858.CD013652
3) SARS-CoV-2 remains infectious in aerosols for at least 16 hours.
This is an early release article by the CDC. These investigators nebulized SARS-CoV-2 and measured the infectivity as far out as 16 hours. They found that SARS-CoV-2 remains infectious in suspended aerosols for at least 16 hours (at which point they stopped testing). This has implications for contact tracing. One may have been exposed to SARS-Co-V-2 long after the index case left the area. How this will change practice remains to be seen.
Fears SC, Klimstra WB, et al. Persistence of severe acute respiratory syndrome coronavirus 2 in aerosol suspensions. Emerg Infect Dis. (publication date online: 25 June 2020 https://doi.org/10.3201/eid2609.201806
4) It is possible to pool patient samples and run a single test in low resource areas.
These authors model a unique solution to the lack of adequate PCR tests. They suggest pooling the tests of several patients and running them as a single sample. If the test is negative, you are done. If the test is positive, each individual needs to be tested separately. They present several scenarios. For example, if the PCR is 70% sensitive and there is a 1% positive rate, 13 patients could be tested as one sample. In this case, only 16% of the number of tests would be needed compared to if each patient was initially tested separately. They present several scenarios in their analysis.
This is not ready for prime time but is an example of a unique solution when there may be limited reagents, etc. Of course, you still do need one swab per person.
Simulation of Pool Testing to Identify Patients With Coronavirus Disease 2019 Under Conditions of Limited Test Availability. JAMA Network Open. 2020;3(6):e2013075. doi:10.1001/jamanetworkopen.2020.13075
5) Finally, how do you make a typical surgical mask into an N95 mask? Just add rubber-bands.
These authors point out that surgical masks are N95 masks in terms of particle permeability. The main issue is that surgical masks leak leading to inhaling non-filtered air. They propose two solutions: One using rubber-bands and the other using a rubber sheet. In limited testing, these modified surgical masks were found to be as good as N95 masks at filtering the inhaled air. These are not yet approved as an official solution, but they have applied for CDC/NIOSH certification.
Data is here: https://www.medrxiv.org/content/10.1101/2020.05.18.20099325v1
Instructions for making the masks is here: https://www.fixthemask.com/make-it