We examine what experts say a second wave of coronavirus might look like, when it could happen, the difference between a "wave" and a "spike" and more. Please note, this story provides an overview of the current discussion, and updates frequently in light of new and changing information provided by health officials, global leaders and the scientific community. It is not intended as a medical reference.
A second wave of coronavirus cases? The latest news
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Why are there more confirmed coronavirus cases now?
There are several explanations for why coronavirus cases are rising now. A greater portion of the population is being tested, for example, so there are more positive test results in total. However, an analysis by ProPublica in late June demonstrates that the rate of positive results is outpacing the rate of expanded testing, meaning testing alone can't be blamed for the recent surge. The need for more hospital beds in affected states like California, Arizona and Texas also suggests that the overall caseload is rising in addition to the greater number of positive results.
It's already starting to happen. So far at least 19 US states have either paused or reversed their reopening plans in response to recent surges in coronavirus cases. For example, Texas and Florida -- two of the first states to lift lockdown restrictions -- recently walked back the reopening of restaurants and bars, which now have had to close their doors for a second time.
In other parts of the world that have experienced a surge of coronavirus infections after lifting lockdown restrictions, many such measures have been reinstated. In June, Germany extended its lockdown in North Rhine-Westphalia by a week and the UK has imposed a local lockdown in the city of Leicester, both due to increases in coronavirus cases.
Until there's an effective vaccine, it's possible that different parts of the US and the world will see fluctuating degrees of lockdown as governments adjust their response in the ongoing battle against the coronavirus.
What are the effects of reopening the economy on coronavirus cases?
Much of the attention aimed at fall has now shifted to concern over the possibility of two potentially lethal viruses circulating at the same time. Redfield told Time Magazine in June, "The real risk is that we're going to have two circulating respiratory pathogens at the same time," referring to both the coronavirus and the seasonal flu.
Basically, the more measures there are in place to help reduce disease transmission -- and the more effectively those measures are followed -- the lower the infection rate may be the second time around, according to the computer model.