Lockdown and social distancing measures are in place in many countries across the world, intended to stem the rapid spread of the coronavirus disease (COVID-19) global pandemic. These measures work by reducing the risk of viral transmission in communities, reducing the burden of the healthcare system in dealing with the surge of patients, overwhelming its resources and workforce. Now, experts warn that these social distancing measures may still be needed until 2022.
The coronavirus disease has ravaged across the globe, affecting 185 countries and territories and has now infected more than 2.15 million and killing more than 143,000 people. The United States has reported the highest infection and death toll, with 667,801 confirmed cases and more than 33,000 deaths.
A team of researchers at the Harvard T.H. Chan School of Public Health has released a new study, concluding that a one-time lockdown will not be enough to bring the pandemic under control. Second waves of the pandemic may peak and could be larger than the current one without continued restrictions.
A second wave of infections
The paper, published in the journal Science, highlights the importance of physical or social distancing and how it can help prevent the second wave of infections.
The study was the first of its kind to use data from two other closely related coronaviruses, the HKU1 and the OC43, to predict how COVID-19 will behave. The two coronaviruses cause a large share of common cold cases, and the team determined how seasonal effects can influence the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
The researchers revealed that if strict social distancing rules, which cut transmission rates by 60 percent, are lifted, this will result in epidemic peaks in the fall and the winter. The size of these epidemics may be similar to what is happening now and would greatly impact healthcare systems.
The researchers explain that one of the problems with strict social distancing is, though it appears to be the most effective strategy at the moment, very little population-level immunity is developed to the virus, and that may itself lead to second waves.
Multiple intermittent social distancing periods
One of the possible methods described by the researchers in addressing outbreaks until a vaccine is developed are multiple intermittent social distancing periods, which can be lifted when cases fall to a certain level. Then, when cases flare up again, social distancing will again be implemented.
It will depend on the season when the cases will surge, and the models show that the social distancing that is happening between 25 percent and 75 percent of the time would both build immunity, and reduce the burden on the healthcare system. As time passes by, more and more people in the population will gain immunity, and social distancing measures may become shorter, with longer intervals between them.
Until a vaccine is developed
The development of a vaccine may take about 12 to 18 months before it can be rolled out. However, vaccines may take a little while to be administered across the globe. Until then, it can be expected that social distancing measures will be in place longer, or maybe imposed depending on the influx of cases.
However, when treatment is developed that can lessen the disease severity or when effective case identification and contact tracing is in place, it will change the situation. Further, the team also provided a scenario if the United States can increase critical care units two times its current capacity, it may shorten the need for prolonged physical distancing measures to mid-2021.
The model also predicts that if the pandemic were over by fall, it would lead to an overwhelmed health care system and many deaths. After the pandemic is over, the virus would spread periodically, just like the flu or the common cold.
“In summary, the total incidence of COVID-19 illness over the next five years will depend critically upon whether or not it enters into regular circulation after the initial pandemic wave, which in turn depends primarily upon the duration of immunity that SARS-CoV-2 infection imparts,” the researchers concluded.
The authors said they are aware that prolonged social distancing, even if it is intermittent, may have negative impacts on economic, social, and educational systems across the globe. The purpose of modeling is not to endorse intermittent social distancing measures but to determine possible trajectories of the epidemic.
- Kissler, S., Tedujanto, C., Goldstein, E., Grad, Y., and Lipsitch, M., (2020). Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period. Science. https://science.sciencemag.org/content/early/2020/04/14/science.abb5793