COVID-19 rate of transmission: What it is, and why it's so important
The street was empty outside a closed movie theater in Malverne Saturday. Credit: Newsday/J. Conrad Williams Jr.
New York State will have its eye on a key number, the rate of transmission, as officials determine to what degree the state should reopen.
Gov. Andrew M. Cuomo said at his daily coronavirus briefing Sunday that he will watch this number and simultaneously have his hand on the "activity valve," guiding policy across the state.
"All that progress we made, by flattening that curve, we could lose that in a matter of days if we're not careful," Cuomo said Sunday.
The rate of transmission is determined, primarily, by the hospitalization rate and total number of coronavirus diagnoses, said Jim Malatras, a member of the state's coronavirus task force, in an interview Sunday. A complex computer model is used to calculate the current rate.
A transmission rate of 1.0 means that each person who has the virus passes it to one other person. A projection above a rate of 1.0 could result in a "spread," Malatras said.
A rate below 1.0 means that the virus is spreading to fewer and fewer people. The current statewide figure is 0.8, meaning 10 positive people are infecting about eight others. The current rate of transmission downstate, including Long Island, is 0.75. The number is 0.9 upstate.
The key is to follow the projections and make sure the figure does not rise past 1.2, Cuomo said.
If the rate is at 2.0, that means one person infects two people, who each then infect two more people. "That's fire through dry grass … now you're in bad shape." Cuomo said Sunday. "We were actually there before we even knew we were there."
The state follows several models and projections, including one from the Imperial College at London. Antibody tests, which are designed to determine whether individuals had previously been infected and conquered the disease, have not yet been fully incorporated into the model, Malatras said.
The state Health Department continues to conduct antibody test sampling at grocery stores, said spokesman Jonah Bruno. It has already sampled more than 8,000 people in the state, he said. Testing was conducted on Long Island over this past weekend.
Cuomo said he will watch the "dials" — number of hospitalizations, number of positive antibody tests and number of positive diagnostic tests. "You open the valve a little bit, phase one, watch those dials like a hawk, and then you adjust," he said.
"This is the balance that we collectively need to strike," he said. "I want to get back to work, my kids want out of the house. I need to do something. I understand. We have to do it intelligently. This is the definition of intelligence in this context."
Scott Eidler covers Nassau County government and politics for Newsday. Scott has worked at Newsday since 2012 and previously covered municipal government and education.
