Because New York was hit with the coronavirus early, before testing was widely available, its official count of infections – at just over 400,000 – vastly understates the scale of its outbreak.

The state’s death toll, which is relatively well-documented, can be used to sketch a fuller picture of the pandemic’s course in New York – and provide better perspective on the current outbreaks in the South and West.

Research indicates that the mortality rate among people who contract COVID-19 is approximately 1 percent or less. This suggests that the total number of infected New Yorkers would be about 100 times the number of deaths, or 3.2 million, or about eight times higher than the Health Department’s tally of known cases.

This is an installment in a special series of #NYCoronavirus chronicles by Empire Center analysts, focused on New York’s state and local policy response to the coronavirus pandemic.

Among patients who die from the disease, the median time from infection to death ranges from 18 to 21 days. With this in mind, death counts suggest that the coronavirus started spreading in New York by late February and peaked in late March.

To be clear, these are debatable assumptions – and the results obtained are at best rough estimates that are useful for illustration purposes only.

The first chart below shows estimated total infection curves, extrapolated backward from death counts, for New York and Florida.

This illustration makes several things clear:

1. By March 1, when the state recorded its first case of coronavirus, thousands of other New Yorkers were likely already infected.
2. By mid-March, when the state recorded its first known coronavirus deaths, the outbreak was spreading rapidly, infecting people at a rate of perhaps 60,000 people per day and climbing fast.
3. The outbreak appears to have peaked in late March, right around the time that social distancing measures, both state-mandated and voluntary, were taking effect – an indication that these precautions helped stem the pandemic.
4. Because New York’s death count peaked at almost 1,000 per day, the state’s infection rate likely peaked at almost 100,000 per day.
5. In Florida, the number of confirmed cases has risen above the number of inferred cases from three weeks earlier – a clear sign that the surge is real, and not just a byproduct of increased testing.
6. Comparing states’ confirmed infection rates currently to what New York reported back in early April is misleading, because New York was testing a much smaller fraction of its infected residents.

The second chart of national data tells a similar story: The current surge in the South and West has not yet come close to the scale of what happened to the Northeast in March and April. However, it appears to be the beginning of a second wave which, in the absence of effective containment measures, could become just as deadly as the first.