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Florida Covid-19 Testing Part 2

May, 1, 2020

In three days, Florida will reduce certain restrictions, such allowing restaurants and retail stores to open up as long as they meet certain social-distancing requirements. Three counties, however, are excluded from these new rules: Palm Beach, Broward and Miami-Dade counties.

In the scheme of things, these new “freedoms” are quite modest compared to some states, such as Georgia, but many residents and experts are still worried these new rules will lead to a spike in new Covid cases.

The original national requirements, which are still in effect, specified four continuous days with lower new Covid cases. As of today, Florida has not even come close to having four days in a row of lower new cases.

Most “experts” have proffered that in order to get back to normalcy, the country needs to substantially increase testing. In a recent post, I listed two major ways to measure testing that epidemiologists recommend.

One recommendation is to complete at least a 152 tests per 100,000 population per day. In Florida, that would require at least 32,000 test per day. Since testing began in Florida it has averaged 6,437 tests per day. If you take out the testing start-up period, the state averaged over the last 29 days 10,274 daily tests.

The World Health Organization (WHO), on the other hand, recommends a different standard for an adequate testing protocol for Covid-19. It recommends to monitor and maintain positive cases at or below 10%. If you are much above that level it means you are not testing enough. Dr. Sanjay Gupta, the medical doctor for CNN also recommends this protocol as well (I know, I’m watching too many news shows).

I’ve updated the latest raw data from The Covid-19 Tracking Project for Florida and have analyzed it. Since March 6th, the state has administered 382,405 total tests.

These tests started out slow, but skyrocketed by April 29th, when the state averaged 6549 tests per day.

On April 26th, the state tested over 9000 individualw in one day, still far below some recommendations that Florida needed to test 32,000 people a day. But the number of positive cases, tells a different story.

The graph above tracks the percent of positive cases found each day. As you can see, in March the percent of positive cases bounced around as the state ramped-up its testing capability. By April, however, the number of positive cases began to stabilize around the 10% level (red line). And by the end of the month, had dropped to 8.8%. For the last week in April, the average percent of positive cases was 9.1%. I’ll keep an eye on this statistic as more testing progresses.

Based on the WHO recommended 10% or less positive test rule, Florida is performing well. As long as positive tests stay below the 10% level, the state is finding most of all the actual number of Covid positive population. The fact that the number of positive tests continue to drop is a really good sign as well.

Can the number of positive cases predict when we an back to business again? Unfortunately, there is really no one accepted standard for when opening. But the WHO has a standard for countries ravished by malaria (I know it’s not a virus). When positive malaria positive tests drop below 5%, the nation can begin the transition to normalcy. Florida is now at 8.8% and seems to be on a downward trend.

Another measure is when the rate of transmission (Ro) drops below one (<1), meaning the virus no longer can spread from person to person. Finally, if the Florida number of new cases decline to near zero. The new cases model, shows that with increased testing the decline in new cases has slowed down, a shown the graph below.

The model’s trajectory still predicts a downward slope but the end date is now beyond the 60 day estimate in earlier models. When the new cases hits the floor, opening up the state will be more viable. No new cases means no Covid deaths in time.

Ultimately, the discovery of an effective Covid vaccine and the inoculation of most of the population will allow us to declare victory. Unfortunately, that day is still far off. Be safe…

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