FWIW this is not uncommon with pandemics. For example, WHO[0] says "During the post-peak period, pandemic disease levels in most countries with adequate surveillance will have dropped below peak observed levels. The post-peak period signifies that pandemic activity appears to be decreasing; however, it is uncertain if additional waves will occur and countries will need to be prepared for a second wave."
For example, during the spanish flu, the second wave was far deadlier than the first. But there were additional factors (WWI and a mutation that made it more dangerous to the young).
This can continue until enough of the population has been infected that we have herd immunity. This is why there's long-term estimates of 20-60% of population being infected[1][2]
FWIW this is not uncommon with pandemics. For example, WHO[0] says "During the post-peak period, pandemic disease levels in most countries with adequate surveillance will have dropped below peak observed levels. The post-peak period signifies that pandemic activity appears to be decreasing; however, it is uncertain if additional waves will occur and countries will need to be prepared for a second wave."
For example, during the spanish flu, the second wave was far deadlier than the first. But there were additional factors (WWI and a mutation that made it more dangerous to the young).
This can continue until enough of the population has been infected that we have herd immunity. This is why there's long-term estimates of 20-60% of population being infected[1][2]
[0] http://www.euro.who.int/en/health-topics/communicable-diseas...
[1] https://www.nytimes.com/2020/03/11/world/europe/coronavirus-...
[2] https://www.axios.com/congressional-physician-predicts-75-15...