https://www.sciencedaily.com/releases/2020/03/200325212154.htm

Using mathematical modelling to simulate the impact of either extending or relaxing current school and workplace closures, researchers estimate that by lifting these control measures in March, a second wave of cases may occur in late August, whereas maintaining these restrictions until April, would likely delay a second peak until October -- relieving pressure on the health services in the intervening months.

However, the authors caution that given the large uncertainties around estimates of the reproduction number (how many people an individual with the virus is likely to infect), and how long a person is infected on average, the true impact of relaxing physical distancing measures on the ongoing COVID-19 epidemic cannot be precisely predicted.