High Pitkin County breakthrough case rate points to unvaccinated visitors
A majority of visitors to the Aspen area are unvaccinated, which may partially explain why Pitkin County has a much higher rate of vaccinated residents testing positive for COVID-19 than public health officials expected, an official said Thursday.
In fact, 66% of all positive COVID-19 cases among residents in Pitkin County in the 28-day period ending Tuesday have been so-called “breakthrough” cases, or those involving fully vaccinated residents, Josh Vance, county epidemiologist, told members of the Pitkin County Board of Health on Thursday.
“The breakthrough rate is a lot higher than expected,” Vance said, adding that it should be around 25% of cases.
Pitkin County registered 55 confirmed breakthrough cases as of July 29, according to previous reports. That number jumped to 75 a week later on Aug. 5, and now stands at 94, which includes only residents, according to Thursday’s dashboard and previous reports.
The county has confirmed a total of 52 new COVID-19 infections in the last seven days, 25 among residents and 27 people from outside the county, according to the county’s COVID-19 statistics dashboard. That means that of the 25 new cases among residents, 19 of them are breakthrough cases.
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In a subsequent interview Thursday night, Vance said the 66% number has puzzled local public health officials, who plan to meet with state public health officials Monday to discuss the local breakthrough rate and try to understand it better.
“Because we do think it’s unusual it’s that high,” he said.
One of the reasons for the higher infection rate among fully vaccinated residents is probably because 58% of visitors to Aspen and Pitkin County are unvaccinated, he said. Public health officials know that from interviews with out-of-county people who test positive in Pitkin County and are asked about their vaccination status.
In other words, the county’s high overall vaccination rate of 66% of residents — 81% have received at least one vaccine dose — is being diluted by unvaccinated visitors.
“Because so many visitors are unvaccinated, it’s creating more risk to residents,” Vance said, adding that the overall vaccination rate drops with so many unvaccinated people circulating in the community. “There’s a great likelihood of exposure.”
COVID-19 cases in Pitkin County involving people from outside the county have come from many different places, including Eagle and Garfield counties as well as Louisiana, Texas, Florida, New York and California, according to statistics Vance presented at Thursday’s meeting.
“Cases are coming from all over the country,” Vance said. “It underscores the fact that we’re seeing a dilution of our vaccination rate.”
Another likely important issue in the county’s high breakthrough case rate is the possible waning of efficacy of the vaccines in the face of the delta variant onslaught, he said.
Pitkin County public health officials have analyzed vaccine data from residents who later tested positive for the virus and discovered that the rate is highest among those who were first vaccinated in January. The next highest rate was among those vaccinated in February, followed by March, Vance said.
“The data suggests that individuals vaccinated early on are likely less protected than those vaccinated later,” Vance said. “That emphasizes the need for booster doses.”
In addition, a recent study that hasn’t yet been peer-reviewed looked at the difference in longer term efficacy of the Pfizer and Moderna vaccines that showed the Pfizer vaccine with reduced efficacy, he said.
If the Pfizer vaccine proves to be less effective at preventing symptoms in fully vaccinated people who later test positive, Vance said he wouldn’t be surprised to see higher breakthrough rates here because a lot of area residents have received that vaccine.
Other possible factors for the higher breakthrough case rate include a possibly higher vaccination rate than previously thought, different testing behaviors between vaccinated and unvaccinated people and higher risk activities for vaccinated people, he said.
Jordana Sabella, the county’s public health director, emphasized that the incidence rate among the unvaccinated is higher than the unvaccinated, and that vaccines remain the best option for controlling the spread of the virus. Getting the vaccine also means that those who end up contracting the virus anyway experience much less severe symptoms, officials have said.
In fact, those 94 breakthrough cases represent just 0.6% of the total of fully vaccinated residents in Pitkin County, according to the county COVID-19 statistics dashboard.
Taken together, the most recent COVID-19 related developments mean Pitkin County currently has a high rate of COVID-19 transmission based on an incidence rate that has been hovering between 150 and 200 cases per 100,000 residents for the last several weeks, he said. The Centers for Disease Control sets the “high” transmission rate at anything more than 100 cases per 100,000 population.
Pitkin County’s incidence rate fell to 141 as of Thursday, the lowest rate in the last two weeks, according to the county’s COVID-19 status dashboard. The positivity rate – which measures the number of positive COVID-19 tests in the last seven days – was at 4% as of Thursday.
And while the county has only detected 18 delta variant cases since May, nearly all the variant cases detected since then have been delta, and public health officials have said they assume that the recent surge in infections is likely due to the more contagious variant of the disease.
Vance also presented results from the county public health department’s study of people with long-term COVID, or those suffering symptoms of the virus at least six months after infection, which showed that a majority suffered lingering symptoms.
Pitkin County registered 157 COVID-19 infections between March and August 2020, and public health officials were able to interview 103 of them six months after their positive diagnosis. Around 42% of those 103 respondents reported zero long-term effects from their COVID-19 infection. For the remaining 58%, most reported between one and three lingering symptoms, though one person had 36 different symptoms and others had between four and 29, according to statistics presented by Vance.
The two most commonly reported symptoms were fatigue and “post exertional malaise,” which affected about 17% of study participants. Those were followed by shortness of breath, impaired smell, ringing in ears, myalgia or muscle pain, hair loss, impaired taste, memory issues and sleep trouble, which all affected between 12% and 14% of participants.
Other reported lingering symptoms include headache, brain fog, weakness, phantom smell, confusion, chest pain, back pain, weight gain, weight loss, joint pain, difficulty walking or running, dizziness, vision problems, numbness, anxiety and excessive thirst.