What we know: Bucks, Montgomery counties have 'substantial transmission' of COVID-19

The CDC has now listed Bucks and Montgomery as "communities of substantial transmission" for the coronavirus, as the number of new cases climbs with the more contagious delta variant. 

Gone are the days of summer when only five or six people per day tested positive for the virus in either county. Bucks reported 75 new cases on Friday and 96 cases were reported in Montgomery County on Saturday, the latest available figures.

Many more could be infected with COVID-19 and not know it, as testing has receded with the availability of vaccines.

The Centers for Disease Control and Prevention recommend that even fully vaccinated people wear a mask in public indoor settings in areas of substantial or high transmission.

Neither county has issued a mask mandate. Pennsylvania health officials have said statewide mask mandates are unlikely, but recommend following CDC guidelines.

"At this point, Bucks County has made no changes in its position on masking of vaccinated people," said Larry King, spokesman for the county. "The commissioners have emphasized that our guidance, like that of other jurisdictions, is always subject to change, depending on the evolving circumstances and numbers."

Montgomery County continues to recommend even fully vaccinated persons wear masks in public indoor settings, said Teresa Harris, public affairs manager for the county.

"Fully vaccinated people might choose to wear a mask regardless of the level of transmission, particularly if they are immunocompromised or at increased risk for severe disease from COVID-19, or if they have someone in their household who is immunocompromised, at increased risk of severe disease or not fully vaccinated," Harris said. 

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Thankfully, cases have also been much milder, public health records show.

In the last month, Bucks lost six people to the virus, according to the Pennsylvania Department of Health.

Montgomery County has reported three fatalities tied to COVID-19 since July 1.  

Bucks County is home to an estimated 628,270 people, according to the U.S. Census. The Pennsylvania Department of Health estimates that 307,498 persons, or 49%, of the population is vaccinated. 

Montgomery County is home to 830,915 persons, according to the U.S. Census. According to the state, 416,659 persons, or 50%, of the people in Montgomery County are vaccinated.

The CDC labels communities of transmission based upon the daily case counts per 100,000 residents and the percentage of persons testing positive for the virus. 

The system for determining the level of transmission in a community is complex.

First, the CDC adds up the total number of new cases in a community within the last seven days. That number is then divided by the population of the county and multiplied by 100,000.

If the resulting figure is between 50 and 99.9, then a community is rated for substantial transmission.

Next, the CDC considers the rate of positivity on nucleic acid amplification tests for the genetic material of the virus. 

The CDC adds up the number of positive tests for COVID-19 during the last seven days. That number is then divided by the number of tests conducted in the community in the last seven days. 

If the resulting figure is between 8% and 9.9%, then a community can also be rated for substantial transmission.

If results from either factor — the new cases or the diagnostic tests — suggest different levels of transmission, then the higher of the two levels is selected by the CDC.

Twenty-four of Pennsylvania's 67 counties were considered to have substantial spread as of Saturday, and one — Crawford County in the western part of the state — was considered to have high spread of COVID.

Only Chester County in the Philadelphia region is not considered to have substantial spread. In neighboring states, all of Delaware and all of New Jersey, except for Warren County, have substantial spread. 

Contact reporter James McGinnis at jmcginnis@couriertimes.com