June 2020 Update
June 7, 2020
UPDATE: Focus on Mortality Rates in Different Populations with COVID-19 and Testing Modalities
This is the third Covid-19 pandemic monthly update from Bowery Consulting (previous updates can be viewed here). This update reviews the Covid-19-related mortality rate in the US by race and age group, with a review of what we know about the disproportionate impact of the virus in the black community and nursing homes. It also discusses the different types of tests for the virus and for antibodies. Please see previous updates for more on what we’ve learned over the past 3 months about treatment research, public health strategies, and more.
Overall Mortality Rates
According to a CDC Pandemic Planning Scenarios document last updated May 20, 2020, the estimated percentage of symptomatic patients who die from Covid-19 is 0.4%. For those over 65 years old, the mortality rate is 1.3%, whereas those younger than 50 years have a mortality rate of just 0.05% and those age 50–64 have a mortality rate of 0.2%. The overall estimated hospitalization rate among symptomatic patients is 3.4%. However, the estimated percentage of individuals with asymptomatic disease is 35%. That means that when you combine symptomatic and asymptomatic people infected with Covid-19, the overall mortality rate is only about 0.26%. In other words, for every one thousand infections, there are 2.6 deaths.
Understanding the Causes of Increased Mortality Rate Among Black Americans
According to research gathered by APM Research Lab from 39 states (plus the District of Colombia) collecting data, approximately 55 black people have died from Covid-19 for every 100,000 black Americans, a mortality rate more than double the rate for Asians (24) and Latinos (25), and 2.4 times that of Whites (23 deaths per 100,000). In Washington, DC, 76% of Covid-19-related deaths are among blacks, although they make up only 44% of the population. In Kansas, blacks make up 6% of the population, but account for 31% of statewide deaths from Covid-19.
The reasons for the disparity in mortality rates from Covid-19 between blacks and non-blacks are numerous. As outlined by the National Medical Association (NMA), health is impacted by “economic stability, physical environment, education, food community and social content and healthcare systems.” And blacks in the US are disproportionately impacted in these areas, they say. Looking at this through the frame of Covid-19, we can see the challenges that are having a dire impact on black Americans:
1. Social distancing and isolation within low-income housing where bedrooms are shared is more difficult, especially in urban areas where the population is disproportionately black
2. Many blacks work in high-risk settings in which they are considered “essential workers” such as hospitals, subways, police departments, restaurants, delivery routes, etc
3. A lack of adequate access to healthcare among black Americans has resulted in a higher rate of underlying conditions linked to severe illness and death from Covid-19, such as diabetes, heart disease, hypertension, COPD, asthma, and kidney disease. In addition these most vulnerable patients are less likely to seek medical attention in a timely manner and may receive less aggressive or timely care because of inherent racial bias within the healthcare setting.
4. The quality of nursing home facilities has been linked to the percentage of deaths seen in those facilities and blacks are more likely than others to reside in lower-rated nursing homes that may have a higher proportion of Covid-19-related deaths
The NMA refers to the overall healthcare deficit seen in the black community as the “Slave Health Deficit.” They say that this represents “an aftermath of years of discrimination, unequal treatment and injustices in healthcare, criminal justice and employment.”
Nursing Homes: The site of 40% of deaths from Covid-19 in the US
It is estimated that, through May 2020, there have been over 40,000 deaths in hundreds of long-term care facilities across the country since it was first found spreading in a Seattle-area nursing home. The official government data on nursing home mortality are still incomplete, but in early June, the Centers for Medicare & Medicaid Services (CMS) began reporting nursing home-specific Covid-19 data. Nursing home case and mortality numbers will be updated weekly. They report that among the 88% of facilities with available information as of May 31, 2020, there have been over 95,000 confirmed cases, over 58,000 additional suspected cases, and nearly 32,000 Covid-19-related deaths—that is a mortality rate of over 20% if you include suspected cases.
Viral and Antigen Testing
The CDC indicates that the mean time between disease exposure and symptom onset is 6 days. This means that about half of those with symptomatic disease experience their first symptom within 6 days after exposure and half experience their first symptom after 6 days or more. Almost all individuals experience symptoms within 14 days and the vast majority within 11-12 days. Certain types of diagnostic testing work best within the first week after the onset of symptoms and others may be used later in infection or after someone has recovered to see if they were previously infected.
Molecular viral testing
This type of test is used to diagnose virus and is most commonly conducted with a nasopharyngeal swab. This test works by converting RNA to DNA and replicating (amplifying) it dozens of times in order to determine whether the virus is present in the genetic material. This type of test is called real-time reverse transcription (RT)-polymerase chain reaction (PCR).
The RT-PCR tests are very sensitive and rarely cause a false positive result. After a week or more of symptoms, false negatives can occur. This is because the amount of virus (viral RNA) present in the upper respiratory tract begins to decline and will eventually become undetectable. The prevalence of virus in the upper respiratory tract when symptoms first appear is also why infectiousness is higher early in the disease. After about the first 7 days, the virus moves down into the lungs in more severe cases. Rapid tests are also available with results in 1 hour, but they may be less reliable than RT-PCR.
Serological testing
This type of testing is used to detect antigens in the blood and is believed to identify if you may either currently have active Covid-19 or if you have previously had the virus and recovered or cleared the virus. There are different types of antigens that can appear in the blood, each with different implications. In individuals with Covid-19, the body will typically begin to develop IgM antibodies about 1 week after infection and IgG antibodies will appear about a week later. When the IgG antigen is present in patients who have cleared the virus, it is believed to show that the body has produced antigens that may provide extended protection or immunity. However, further evaluation is needed to determine how much, if any, immunity is provided and for how long. With one common serologic antibody test known as the ELISA (enzyme-linked immunosorbent assay) SARS-CoV-2 surface protein is attached to a plastic plate, and some of the individual’s blood serum is added to determine if there are antibodies that recognize and stick to the virus’s surface protein.
There are other serologic antibody tests that get results more quickly, though they may not be as accurate. These rapid tests require less blood—just a finger prick rather than blood drawn from a needle by a healthcare professional in a clinic. The blood comes into contact with a test strip and if there are antibodies, they can be quickly identified and sorted and color coded according to whether they are IgG or IgM. These rapid tests typically take 10-30 minutes, whereas the lab-based ELISAs take several hours, but can test many samples at once. However, the rapid tests may often falsely detect antibodies to other coronaviruses, rather than Covid-19. If you test positive for antibodies with a rapid test, it is recommended that you confirm the result with an ELISA test. The sensitivity of the tests is also a potential issue that can cause false negatives—a test may not be sensitive enough to detect SARS-CoV-2 antibodies when they are, in fact, present.
The Potential Benefits of Testing, Contact Tracing, and Social Distancing
Both virus and antigen testing play an important role in the fight against Covid-19 and they should both be used wherever they provide benefit. For instance, since the virus may be undetectable after 7 days of symptoms when using RT-PCR testing, antibody testing may be an alternative to confirm active disease in this situation. Regardless, it is important to wait a substantial amount of time after an individual has stopped having symptoms before allowing them back to work. It is unclear exactly how much time is safe, though.
To avoid spikes in transmission, a combination of aggressive testing and contact tracing is going to be the most important tool. This will be essential as we relax the social distancing guidelines. Rapid POC (point of care) testing will be essential to make this approach practical and scalable for a large population. However, we still don’t know what being seropositive for SARS-CoV2 antibodies means in terms of immunity or infectiousness. So for now, we need to continue with social distancing measures and the wearing of masks around others.
Thank you for reading and please feel free to drop me a line if you have any feedback. Stay safe.
Brett Moskowitz
President, Bowery Consulting
June 7, 2020