With the current capacity of intensive care units (ICUs) and with no vaccines available or specific treatments, intermittent measures of social distancing may have to be maintained until 2022, according to a study published in the journal ‘Science’ by researchers at the Harvard School of Public Health.
“Intermittent distancing may be required until 2022 unless the capacity of intensive care units is substantially increased or treatment or vaccine is available,” the T.H. School team of scientists states in their report. Chan, who have based their findings on the information available on Covid-19 and other coronaviruses to create various global pandemic scenarios and establish a pattern of transmission of the new disease, which has infected nearly 2 million people worldwide.
This finding debunks the estimates of the White House of “open soon” the US again, the worst-affected country with 609,500 cases and 26,000 dead- and warns that the virus would appear fairly quickly if restrictions are lifted completely.
How long will confinement last? When will we end the virus? As quarantines lengthen, governments around the world are trying to solve the puzzle of when to start removing mobility restrictions and what steps will be needed to keep the spread of the coronavirus under control in the future.
The main conclusion reached by this group of scientists is that the incidence of Covid-19 disease over the next five years will depend on whether or not it enters regular circulation (i.e., if it becomes seasonal) after this initial pandemic wave, which in turn depends mainly on the duration of immunity caused by SARS-CoV-2 infection and the intensive care units available in each health system.
In fact, scientists warn that by simultaneously overriding all social distancing restrictions, one could risk delaying the peak of the epidemic and potentially making it more severe.
“If the approach chosen is intermittent distancing [lifting restrictions and then reapplying them when a certain number of cases or pressure on ICUs are reached], it may be necessary to do so for several years,” insisted Dr. Marc Lipsitch, author of the study and professor of epidemiology at Harvard School of Public Health, in statements collected by the US press.
The experience of countries such as China, Italy, and the United States shows that Covid-19 can saturate even the medical systems of more resourced nations, but without pharmaceutical treatments available, containment measures focus on tracking contacts with the infected, quarantines, and social estrangement. “The intensity required, the duration and urgency of these responses will depend on both how the initial pandemic wave develops and the subsequent transmission dynamics,” they indicate.
The intensity and timing of subsequent outbreaks will depend on the time of year and, to a lesser extent, the magnitude of seasonal variation in transmissibility and the level of cross-immunity that exists among beta-coronaviruses.
Social distancing strategies could reduce the degree to which infections saturate health systems. For example, “highly effective” distancing could reduce the incidence of SARS-CoV-2 enough to make a strategy based on contact tracing and quarantine, as in South Korea and Singapore. But on the contrary, less effective and unique distancing measures could lead to a prolonged single-peak epidemic, perpetuating the pressure on health systems and the required duration of distancing. So unless ICU capacity increases or treatment or vaccine is available, intermittent distancing may be required until 2022, they argue.
Furthermore, the study authors highlight that they are aware that prolonged distancing, even if intermittent, can have “profoundly negative” economic, social and educational consequences and that serological testing is essential to understand the extent and duration of SARS-CoV-2 immunity. This information will help determine the “post-pandemic dynamics of the virus.”
Intermittent social distancing
There are studies that conclude that the early implementation of a strong social distancing is essential to control the spread of the coronavirus and that, in the absence of the development of new therapies or preventive measures, such as finding and quarantining aggressive cases, intermittent distancing measures can be the only way to avoid overwhelming ICU capacity while creating population immunity.
The social distancing intermittent could prevent ICUs from being saturated. The available information records that there is a delay of approximately 3 weeks between the start of social distancing and the maximum demand for critical care. The time period between distancing measures increases as the epidemic continues, as the build-up of immunity in the population slows down the resurgence of infection.
Increasing intensive care capacity allows population immunity to accumulate more rapidly, reducing the total duration of the epidemic and the total duration of social estrangement measures.
In all modeled scenarios, SARS-CoV-2 was able to produce a substantial outbreak regardless of the time of year. Outbreaks in spring and winter had lower peaks, while those in autumn and winter led to sharper outbreaks.
Depends on immunity
Many of the scenarios analyzed by the authors of the article estimated that, over the next five years, SARS-CoV- 2 would enter the circulation along with other beta coronaviruses, possibly in annual, biennial or sporadic patterns. If this new coronavirus generated short-term immunity in the infected (40 days, for example), annual outbreaks will be caused, while if immunity proves to be long-term (two years), the outbreaks would be biennial. And if immunity to SARS-CoV-2 turns out to be permanent, the virus could disappear within the next five years or more after causing a major outbreak.
In the case of finding an effective treatment or a vaccine, the duration and intensity of the social distancing necessary to keep the pandemic under control would be reduced. Treatments could reduce the contagion rate and, consequently, the ratio of people needing hospital admissions to intensive care, while a vaccine would accelerate the accumulation of the immunity rate in the population, reducing the total duration of the epidemic.
Return to an intermittent “normality”
Different countries, including Spain or Germany, are already presenting their plans for a return to “intermittent normality” and very different from before the virus.
In parallel, almost all “confinement” strategies have as a cornerstone the massive distribution of rapid diagnostic tests accurate enough to detect who has and who does not have antibodies against the coronavirus. The controversial issue of “immunity certificates” is on the table in some countries.
For the time being, and as the race for the vaccine continues to progress, in the United States the different local authorities are implementing measures of confinement and social distance in the states. This social estrangement has been defined as “one of the most powerful weapons” against Covid-19, according to statements by director of the U.S. Centers for Disease Control and Prevention (CDC), Robert Redfield. “If we can maximize that social estrangement, we can limit the capacity of this virus.”
But, according to the authors of the report published this week, “even in the case of an apparent elimination [of the virus], surveillance on SARS-CoV-2 must be maintained, since a resurgence of contagion could be possible until 2024″.