By Jerry R. Youkey, M.D.
With flu season and indoor weather upon us, and our third stair-step wave of the COVID-19 pandemic raging around the world, U.S. cases reached a single-day high of 128,000. Despite this, reliable data for decision-making remains limited, because we are still in our first annual cycle with this new human pathogen. Here is some information I believe is reasonably accurate and a credible basis for individual decision-making.
In the United States we are approaching more than 10 million documented cases of COVID-19 and 240,000 related deaths. In 10 months, more people have died from COVID-19 than died from flu over the past five years. Our hospitals and health care providers are becoming overwhelmed and considering rationing of care.
In the United States, COVID-19 cases are escalating more rapidly than related deaths. Although better medical care may account for some of this decrease in mortality rate, it is more likely the result of pandemic fatigue, with younger, lower-risk people resigning themselves to infection, while many older, higher-risk people continue precautions. It also may reflect the greater than two week lag between increased cases and increased deaths. Time will tell.
Takeaway: This virus does not appear to be seasonal, which decreases the potential success of a vaccine and means that we can’t take time out from safety precautions during the off-season.
There are two types of screening tests. The reverse transcription polymerase chain reaction (RT-PCR) test is the gold standard. It detects viral genetic material in a person’s respiratory sample and has a false positive rate of less than 1%. Research at Johns Hopkins in Baltimore, Maryland, revealed that, depending on timing of testing during illness, the false negative rate ranges between 100% on day 1 and 20% on day 8 because accuracy is correlated with viral load. Thus, when an RT-PCR test is positive, the person has COVID-19 — but if the test is negative, there is a 20%-100% chance that it is missing an infected person.
Antigen tests, like ID Now, are based upon detection of viral particles. They are less reliable than RT-PCR, but attractive because they are quick.
The blood antibody test indicates that a person has had COVID-19, but has no role in screening for active, communicable disease, because it takes two to three weeks following infection to create measurable antibodies. How long effective COVID-19 antibodies last is unknown, but there are an increasing number of people with well-documented COVID-19 reinfections, indicating that at least some people are subject to reinfection 90 days after initial illness.
Takeaway: A negative screening test does not mean that it is safe to be around an individual who has been exposed. Therefore, an exposed individual should be quarantined for two weeks, even if asymptomatic with negative screening tests. A person with COVID-19 should remain in isolation for 10 days after onset of symptoms and resolution of fever for 24 hours without the use of fever-reducing medications. Patients with severe illness warrant isolation for up to 20 days after onset of symptoms.
Overall mortality rate of COVID-19 has been reduced by health care providers learning to provide better supportive care to patients in hospitals, at least as long as hospital beds remain available. But an unknown number of survivors suffer long-term side effects, including cardiac muscle damage from myocarditis, causing chronically weakened heart contractions. Although there are many promising therapies under development, there is currently no proven treatment available.
Recently, the FDA approved remdesivir for use in older children and adults, noting that it shows modest reduction in recovery time. However, the World Health Organization recently released data demonstrating that remdesivir, hydroxychloroquine, interferon and lopinavir, singly and in combination, have little or no effect on mortality, need for a ventilator or length of hospital stay.
Finally, studies of both dexamethasone and monoclonal antibodies in COVID-19 patients have shown mixed results.
Takeaway: Without effective treatments, avoidance of infection is our best survival strategy.
Some are advocating herd immunity, which happens when a large portion of the population is infected and develops natural antibody immunity, causing the virus to become suppressed because there are too few susceptible individuals to sustain an outbreak.
It is estimated that herd immunity for COVID-19, which may prove not possible, might occur following infection of about 50% of our population. An estimated 10% of our population has been infected to date.
So we might have herd immunity following infection of 170 million people, 2 to 7 million of whom will die. Almost 80% of those who die will be over 65. Then, each time the surviving population with immunity from natural antibodies decreases to an unknown critical level because of either waning antibody levels or death, we will see a resurgence. That could be months or years, depending upon the strength and sustainability of the natural antibody response.
Takeaway: If we elect the herd immunity route, my wife and I prefer to be in the portion of the population that does not get infected.
There are currently four vaccines in phase 3 clinical trials in the United States. We may have one or more vaccines available within the coming months. However, experience suggests that fewer than 50% of our population will take the vaccine once it becomes available.
Further, access may be significantly limited due to the need for two injections several weeks apart; requirement for ultra-cold storage as low as -94 degrees Celsius; and inadequate supply and distribution of the vaccine and syringes. Consequently, it is unlikely that we will have conclusive data for at least two or three years to determine if — and for how long — vaccination prevents COVID-19 infection in all population demographics.
Takeaway: My wife and I will strive to minimize our risk of infection to the extent that we can psychologically tolerate the necessary lifestyle, hoping for proof of a highly effective vaccine by 2022. And that is even if we are fortunate enough to receive a proven safe and presumably effective vaccine in the coming months.
SITUATIONAL RISK CALCULATORS
So, what is that necessary lifestyle? Without question, the safest course is that followed by a friend of mine who has a number of comorbidities and a wife who is a cancer survivor. They have not socialized at all. Groceries and other needs are delivered and even when she walks the dog, she wears a mask and avoids getting within 6 feet of her neighbors.
The other extreme is business and life as before COVID-19. The question is how to determine what in-between behavioral risk is acceptable to each of us, realizing the incredible toll of loneliness and isolation on our individual and collective well-beings.
A behavioral risk calculator may help. One of my favorites is the COVID Situational Risk Calculator (covidcalculator.xyz). Although approaches vary, consistent factors are:
- Test positivity rate where you live
- Outdoor vs indoor venues
- Size of the room
- Size of the crowd
- Percentage of mask utilization
- Availability of alcoholic drinks
- Social distancing
- Length of exposure time in the situation
- Use of public transportation
- Use of public restrooms
As an example, with the current 5.6 to 6.8 test positivity rate in South Carolina, in a crowd of 100 people there is a 100% probability that someone has COVID-19.
Takeaway: Determine your risk of COVID-19 exposure under different circumstances and decide which situations are acceptable to you.
Based on our assessment, my wife and I will:
- Be outside whenever possible.
- Attend only events where social distancing and masks are required.
- Strive to be with groups of 10 or fewer people known to us who practice similar prevention behaviors.
- Avoid crowds of more than 30 people.
- Keep our flu vaccinations current.
- Thoroughly wash our hands as often as practical.
- Use hand sanitizer regularly.
- Take the COVID-19 vaccine when available if approved through normal policies, procedures and processes. Even then we will continue precautions, awaiting clear and conclusive data documenting broad and enduring efficacy of the vaccine.
We know that doing all of this will not guarantee our safety, some of it may be unnecessary, and it will change as we learn more about this disease, but none of it seems unreasonable at this time.
Jerry R. Youkey, M.D., is the retired founding dean of the University of South Carolina School of Medicine Greenville