Continue with more modest restrictions, keep an eye on the data and focus on hospitals and protecting the most vulnerable.
One One of the key questions that Americans think about is when government restrictions aimed at controlling the coronavirus epidemic can be safely lifted. In most states, we now have enough information to say that the strictest measures can be relaxed.
California is a good example. A review of the data shows that in mid-March, when the state imposed severe restrictions on social contact and personal movement, the rate of SARS-CoV-2 infections was already beginning to slow. The CDC’s Monitoring of Data Recording COVID-19 Hospital Admissions in the San Francisco Bay Area since the beginning of March, it appears that the highest number of hospital admissions took place between 21 and 28 March. Hospitalization is required approximately 12 to 14 days after infection with SARS-CoV-2. Thus, it is possible that the infections peaked before the most restrictive of the Bay Area orders issued on March 16.
Another CDC analysis of how rapidly reported cases of infection increased in four metropolitan areas of the US – Seattle, San Francisco, New York City and New Orleans – examined the timing of several emergency measures, including limits for mass meetings, school closings, and home delivery. In the four metropolitan areas, the authors found a significant decrease in the relative increase in the number of reported cases following local and national emergency statements and a continued decrease after a ban on mass gatherings. However, there was little further decline in the growth of cases in the two weeks after those who stayed at home in mid-March.
Another report looked at the timing of various interventions in Wuhan, China, and their association with the reproduction number – the number of new cases, caused on average by a primary case over time. When that number drops below one, the epidemic stops growing. Remarkably, the reproduction number for SARS-CoV-2 began to drop dramatically in mid to late January, before the implementation of the strictest house arrest policy in early February. Interventions prior to that included restrictions on air travel and rail travel, local traffic bans, increased mask wear, restrictions on social gatherings, isolation of sick people, and quarantine at home for those exposed. By the date of the universal home restriction, the number of reproductions had fallen to 1.2 and only four days later to less than 1.0.
For our part, we looked at the relationship between the timing of at-home orders and the spikes in reported cases in 31 U.S. states. We could not find a clear pattern regarding the timing of such orders and the peaks in case numbers, suggesting that there is no connection between the orders and the restriction of cases. If there had been an effect of such home orders on the number of new cases, a consistent time-dependent effect would have been expected – that is, a clear, observable average time, say ten to fourteen days from the date of the order to the peak. That was not seen.
Closing down major sectors of society is a blunt tool and its use involves huge costs: the disruption of education, economic activity and social interactions. The continued and possible future use of such people who stay at home deserves a timely and rigorous evaluation. We want to know as much as possible how necessary and how expensive each intervention (for example, limiting meetings, closing restaurants and retail) stands alone. In the field of public health, the first principles of disease control dictate the use of the least costly set of interventions sufficient to prevent and reduce disease.
Overall, several evidence suggests that the rate of new SARS-CoV-2 infections had dropped significantly before government officials imposed the strictest restrictions. These findings, along with the fact that most hospitals, outside certain severely affected areas such as New York City, had sufficient capacity throughout April should give us confidence that self-protective changes in personal behavior along with testing, isolation and quarantine can adequately reduce the epidemic.
It is time to move away from restrictions such as the prohibition of access to outdoor areas, universal home restraining orders and the closure of small businesses. In stages and by viewing the positivity data from tests in key populations and COVID-19 related emergency and hospital visits, we can return to work and school while limiting personal contact with measures such as occupancy limits, washing and establish a policy for paid sick leave to enable sick workers to avoid others and reduce the spread of infections. Public health should focus on protecting the most vulnerable through screening and rapid response to outbreaks in nursing homes and shelters.
Finally, to ensure that we use the least restrictive means needed, we must also focus on keeping hospitals above water. This can be done by specifically adapting the policy to the hospital admissions of COVID-19 patients and the local bed capacity for their care (for example, by deploying 50 percent of the beds for acute care). Leading indicators such as daily COVID-19 related outpatient and emergency care visits can now be monitored to provide an early warning system.
The findings described above and increasing experience in other environments lead us to believe that relaxing the strictest interventions and continuing more modest interventions will not lead to an uncontrollable resurgence in cases.
Jeffrey D. Klausner, a former CDC physician, is a professor of medicine and public health at UCLA. Rajiv Bhatia, a former deputy health officer in San Francisco City and County, is an assistant clinical professor of medicine (affiliated) at Stanford School of Medicine.