Commentary—Regarding Relaxation of COVID-19 Pandemic Precautions
At his news conference on Sunday, March 29, President Trump backed off his earlier goal of relaxing restrictions and going back to work by Easter (April 12); he said that the White House’s social distancing guidelines of avoiding nonessential travel, not going to work, not eating at bars and restaurants, and not gathering in groups of more than 10 will be extended until April 30 and perhaps until June.
Stay-at-home guidelines have been instituted at a U.S. state level starting in California on March 19, and within a few days in more than half the states and the Navajo Nation, with many cities and counties in 13 additional states joining in. However, 11 states have no stay-at-home guidelines at this time. The result is an uneven mix of local and state directives for “shelter in place,” or “safer at home”, but at least 229 million people (almost 70% of the population) in 26 states, 66 counties,14 cities, and one territory have been urged to stay at home according to the New York Times (https://www.nytimes.com/interactive/2020/us/coronavirus-stay-at-home-order.html).
As we continue to significantly restrict business and personal activities throughout the world, the general public and elected officials have naturally started to question how long these restrictions should continue. Many opinions have been voiced, often based more on the individual’s wishes to resume normal life than on evidence and sound epidemiologic reasoning. However, premature relaxation of restriction would be disastrous. So on what information SHOULD we base infection-control decisions?
By common sense, it is reasonable to relax restrictions in a given area when such relaxation will not increase the number of cases. That would be the case when there is some combination of the following:
- There are few or no people with transmissible infection within the area
- There are few or no people with transmissible infection entering the area
- Enough people in the area are immune (through prior infection or, eventually, vaccination) so that the case transmission rate (R0) is significantly lower than that when the bulk of the population was vulnerable (ie, some degree of herd immunity)
- Cases that do develop are rapidly identified and isolated
Having few or no people with transmissible infection is the most obvious component. Although a goal of NO cases is theoretically ideal, it is unrealistic on a practical level. A recent (3/29/20) possible standard was published by Dr. Scott Gottlieb and colleagues and the American Enterprise Institute (https://www.aei.org/research-products/report/national-coronavirus-response-a-road-map-to-reopening/) suggesting a number of factors, including having a 14-day period of daily decline in the number of cases; local hospitals being able to safely treat all patients requiring hospitalization without resorting to crisis standards of care; and the state having the capacity to test all people with COVID-19 symptoms and conduct active monitoring of all confirmed cases and their contacts. However, whatever the ultimate criteria, it must be recognized that a non-zero incidence of transmissible infection in a region with a significant number of susceptible people means that region remains at risk of the geometric increase in cases that occurs when viral replication is unrestrained by public health measures.
Equally essential for safe relaxation of public health distancing measures is the need to
- Minimize movement into the newly-relaxed area by people from higher-risk areas
- Minimize movement out of the relaxed area into higher-risk areas from which people could return with infection
Movement control is particularly challenging in the U.S. because current planning discussions are based on the artificial administrative boundaries of town, city, county, and state rather than the natural regions within which we travel and interact as determined by our social/commercial networks.The normal tight interconnection between neighboring communities or cities and their suburbs means relaxing one but not the other would be a significant challenge to enforce and monitor. Planning that defines a region by taking into account the normal human traffic patterns within a region is more likely to be safe and successful.
Because there will be a non-zero incidence of cases in any relaxed-restriction area and because complete interdiction (voluntary or otherwise) of all traffic between higher- and lower-risk areas is not likely, the identified case rate and transmission rate within an area deemed “low-risk” is only a snapshot in time that must constantly be reevaluated by on-going surveillance.
Thus, from the above it is clear that relaxation of social distancing and reopening of normal business activity cannot be done safely without first doing
- WIDESPREAD testing within the region in which relaxation of standards is considered in order to reliably identify disease incidence and transmission rate
If widespread testing is not done in the area and decisions are made based on the results of our current highly selective testing of certain symptomatic patients, then the asymptomatic and mildly symptomatic potential transmitters remain unidentified and rapid disease transmission will likely return when an area is thus mistakenly designated as low-risk.
To deal with the inevitable cases that DO continue to pop up in a low-risk area, testing must continue to be done liberally on an ongoing basis so that infected people can be identified and then isolated appropriately and their contacts extensively traced, tested, and isolated if positive or quarantined if negative.
Thus, in order to safely relax generalized social distancing precautions within an area, we need to
- Make and distribute as many rapid, point-of-care tests as possible
- Expand testing to include patients with a broad range of signs and symptoms, including those with mild or no symptoms
- Do ongoing surveillance and testing of possible new cases
- Rapidly identify and test contacts of positive cases
- Engage a large number of people to do tests, track cases, and monitor isolation and quarantine adherence
- Communicate with the public frequently and using many modalities regarding who can travel where and when
- Nation-wide policies
Rapid point-of-care testing is important because self-directed isolation is less likely to be adhered to when there is only assumption of possible illness rather than a test-based diagnosis and because contact identification and tracing can begin immediately without having to track a patient down days later. Some countries have had success using apps to monitor and communicate with positive cases.
In addition, antibody testing of people already infected by the virus combined with reliable data on what titers are protective will provide reassurance on which patients are at low risk and can return to public activity, particularly assisting with patient care.
If these things cannot be done, then relaxing contact precautions is likely to restart or worsen an outbreak. If cases continue to occur or it is not possible to significantly reduce contact with areas of active transmission, then precautions need to be reinstated.
This approach appears to be similar to the method by which China and South Korea controlled their epidemic. However, extrapolations may be difficult because of differences in the structure of government, as well as political and social differences. In addition, the genetic polymorphism of the ACE2 receptor that is the entry point for the novel coronavirus possibly causes differences in susceptibility, symptoms, and outcome of COVID-19.
For adults over age 60, those with underlying health conditions, and others at heightened risk from COVID-19, physical distancing measures and limitations on gatherings may need to be maintained until drugs or vaccines become available.