COVID: Asymptomatic infections in nursing homes

Yet another article documented a high percentage of asymptomatic people with PCR-documented SARS-CoV-2 infection, this one in Maryland nursing homes/longterm care facilities (see covid asx nursing homes jamaintmed2020, or doi:10.1001/jamainternmed.2020.3738)

 

Details:

-- universal PCR testing was done on previously untested residents in 11 Maryland long-term care facilities where prior targeted testing had been performed based on symptoms, and there were known positive Covid-19 cases

    -- 9 of the sites were nursing homes, 2 were assisted living facilities

    -- days between index case and testing: 3-19, mostly around 6 to 7; percent with positive tests: between 10% and 90%, overall 40%

-- 2 week follow-up telephone calls in 7 of the facilities were done to get information regarding hospitalization and mortality status of all residents tested

 

Results:

-- targeted symptom-based testing: 153 cases identified at 11 facilities within 20 days of detection of the index case

-- of the remaining 893 residents who were tested through universal testing: 354 (40%) tested positive, increasing the total from 153 to 507 positives

    -- 281 (55%) of these were asymptomatic

-- there was 2-week followup information available for 426 of the residents in 7 sites (177 positive for SARS-CoV-2, 249 negative)

    --154 of the 177 (87%) were asymptomatic and  identified by universal testing

    -- within 14 days of this testing, 20 of the asymptomatic people (13%) were hospitalized and 7 (5%) died [no data on how many remained asymptomatic vs how many were presymptomatic]

 

Commentary:

-- in this nursing home study, 40% of SARS-CoV-2 positive patients in 11 Maryland long-term care facilities were identified through universal testing, well above and beyond what was found in an initial targeted symptom-based testing

-- the early CDC recommendations were to test based on the presence of typical symptoms, most often cough and fever, though even early studies showed that almost half of the patients with Covid-19 did not have the symptoms. However, this focus on symptom-based Covid assessment (perhaps largely because of the grievous lack of appropriate testing kits) likely led to the huge outbreaks found in long-term care facilities, with their associated very high mortality rates. And likely the extensive spread of virus in the communities. And this approach fostered the counterproductive belief in the general population and with health care workers that it was the symptomatic people who were dangerous in terms of potential transmission

-- and, we do know from several prior studies that unrecognized asymptomatic infected people can perpetuate the infection (see http://gmodestmedblogs.blogspot.com/search?q=covid+asymptomatic), which also includes articles on other nursing homes, very high asymptomatic rates in homeless persons (http://gmodestmedblogs.blogspot.com/2020/04/covid-asymptomatic-homeless-patients-in.html), and generally 10x higher seroprevalence than have known Covid-19 cases (http://gmodestmedblogs.blogspot.com/2020/06/covid-seroprevalence-10x-higher-than.html)

--but we do need better data, generated from studies of universal testing/finding asymptomatic people, of the actual transmissability rates of those with asymptomatic infections (R₀ value) vs symptomatic persons, as a means to fine tune our approach to this pandemic

 

 limitations of the study:

-- symptom status was only available at the time of testing and based on reports from the facility staff

-- follow-up data were only available for 7 of the 11 original testing sites

-- PCR testing has a significant number of false negative tests, and this seems to vary dramatically by time since infection. This is known best for those who are of symptomatic infection, where false negative tests are the lowest about 8 days after symptom onset (still 20%, but much better than even a few days before or after that: see http://gmodestmedblogs.blogspot.com/2020/05/covid-false-negative-pcr-results-over.html )

 

So, I bring up another article documenting that:

-- asymptomatic infection seems to be very common

-- targeted testing by symptoms will miss a lot of cases

-- decreasing regulations on use of PPE in those who are not knowingly taking care of Covid-19 patients will very likely increase the exposure of those people to asymptomatic infected patients and increase their likelihood of becoming infected

-- and, the bottom line is (and has been since the beginning) testing, testing, testing. And this and other studies confirms that it should be universal testing, not targeted testing. And that we cannot let our guard down....

geoff

 

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