On Wednesday, for the first time since March 12, NYC reported no new deaths from COVID-19. To put that number into perspective, during the peak in mid-April, NYC reported an average of 500 deaths a day. This is encouraging news, and worth celebrating. Preventative measures—closing businesses, the public adopting physical distancing habits, an increase in the practice of mask-and frequent hand-washing—have been proven effective at limiting the spread of the disease.
However, it is important to remember that a single day’s COVID-19 death rate is not an indicator of what is happening on that day in terms of infection rates, but rather a glimpse into how effective such measures were weeks, or even months earlier.
Death rates are an indicator of infection rates from previous weeks
A study published in the journal the Lancet shows that the time between onset of COVID-19 symptoms and death is, on average, 17.8 days. When you factor in that symptoms start a 5 to 6 days after exposure, and within an average range of between 2 to 14 days, the death rate on a particular date indicates who got sick, on average, 23 days before. That puts us back in the early-to-mid May, when much of the city was still in lockdown.
Given the protests of this week, as well as the anticipated end of lockdown on June 8, the number of new cases seems likely to rise, which could mean an increase in the number of deaths about three weeks from now.
When it comes to assessing COVID-19 rates in NYC, it’s important to look at the daily number of new confirmed cases, which is a glimpse into what’s been happening with transmission rates in the past couple of weeks. These numbers are a little harder to assess, as delays in reporting means daily tallies can take up to a week to finalise, but the numbers of new cases recorded on May 29, one week ago, was 460, down from the highest daily tally of 6,368 new cases on April 6.
A day of no new COVID-19 deaths in NYC—or any other city—is cause for celebration, and a chance to reflect on the fact that preventive measures really do work. It doesn’t mean we don’t need to wash our hands, wear a mask or maintain physical distance, so we can continue to limit the rate of new infections.