COVID: Asymptomatic OB patients

Finally, finally, finally: a study of universal screening, identifying a high percentage of asymptomatic patients with SARS-CoV-2. This study was done in pregnant women admitted for delivery (see Covid asx pregnant women nejm2020 in dropbox, or DOI: 10.1056/NEJMc2009316)

Details:

-- study done in New York, at Columbia University, where they implemented universal SARS-CoV-2 testing

-- 215 pregnant women were assessed by nasopharyngeal swabs between March 22 and April 4

-- 4 women (1.9%) had fever or other symptoms suggestive of Covid-19, all tested positive for SARS-CoV-2

-- 210 of the 211 women were tested who were without symptoms and were afebrile on admission

Results:

-- 29 (13.7%) of the asymptomatic population were positive for SARS-CoV-2

    -- therefore, 29 of 33 positives for SARS-CoV-2 were asymptomatic (88%) on admission

-- of these 29 asymptomatic women, 3 (10%) developed fever before discharge (median length of stay: 2 days)

    -- 2 of these patients got antibiotics for presumed endomyometritis

    -- one patient who had a negative swab on admission became symptomatic postpartum and 3 days later SARS-CoV-2 was positive

Commentary:

-- this study does highlight the high relative prevalence of asymptomatic SARS-CoV-2 infection in pregnant women admitted for delivery: about 90% of the women with the virus were asymptomatic

    --and one SARS-CoV-2 negative woman on admission became symptomatic and positive for SARS-CoV-2

-- A prior Chinese study had confirmed 3 cases of vertical transmission of SARS-CoV-2 from mothers to newborns, which i think really reinforced the importance of testing all pregnant women at the time of admission to the hospital for delivery, isolating them if they were positive to protect other women, and assessing their newborns (see http://gmodestmedblogs.blogspot.com/2020/03/sars-cov-2-vertical-maternalneonatal.html )

-- this study reflects effectively a point in time. Only a few of the women were symptomatic on admission or during their hospital stays. 

    -- it would have been very useful to have follow-up in this study to see what percentage of the women who were SARS-CoV-2 positive and asymptomatic ultimately developed symptomatic Covid infections over the next few weeks, vs those who remained asymptomatic

-- there are clear issues about generalizability of this study:

    --this was done in New York, with a remarkably high rate of ambient Covid cases. Therefore their finding of positive SARS-CoV-2 in 13.7% of asymptomatic women at the time of admission is no doubt higher than in other areas of the country.

    --pregnancy has a unique effect on the immune system, with different effects on the immune response and tropism of viral and other pathogens, and changes in a woman's susceptibility and severity of some infectious diseases: see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3025805/ . and, we do not know how/if SARS-CoV-2 differently affects the maternal/placental/newborn responses in late (or any stage) of pregnancy

    --we do not know what % of the women will remain asymptomatic carriers of SARS-CoV-2, nor for how long.  It was notable in the Diamond Princess cruise ship, that 18% remained asymptomatic: see https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.10.2000180

--and, given the likelihood of vast percentages of patients being asymptomatic (either newly infected and ultimately to become symptomatic, or who will remain asymptomatic), the only effective ways to prevent the continued spread of this pandemic is to identify those people who are SARS-CoV-2 positive and isolate them until they are no longer able to transmit the virus, or wait the 1-2 years til we have a vaccine (or, i suppose, wait until 65% or so of the population gets infected and develops herd immunity....)

So, I would argue that the study highlights the extreme importance of testing asymptomatic people for SARS-CoV-2 infection:

-- as a predictor of ultimate Covid-19 cases ("hot spots"), and where and when to deploy more aggressive public health measures and resources for those who become infected

-- to localize positive asymptomatic SARS-CoV-2 people, with close follow-up/quarantining of those positive (and repeated testing to see how long they remain positive)

    -- and a more focused systematic intervention to effectively identify asymptomatic contacts of positive cases and quarantine them from further spreading the disease (as done successfully in other countries)

and, we should have a massive system of routine testing of asymptomatic people:

-- a sentinel sample from different areas in the country as a means to identify the spread of SARS-CoV-2

    -- an interesting study looked at sewage as another possibility to monitor the spread of SARS-CoV-2 prior to clinical outbreaks: http://gmodestmedblogs.blogspot.com/2020/04/covid-answer-is-in-sewage-and-another.html

-- routine assessment of those in high population-dense areas, such as nursing homes, cruise ships, etc

-- all patients admitted to the hospital, as a means to triage and co-locate those who were SARS-CoV-2 positive vs negative, and decrease the exposure of the non-Covid-positive population

-- all healthcare workers and others at high risk of exposure to SARS-CoV-2 positive people, on a routine basis (perhaps every 2 weeks), over and above using maximal PPE

-- And, these test need to be rapid ones with results within minutes

geoff​

If you would like to be on the regular email list for upcoming blogs, please contact me at gmodest@uphams.org

to get access to all of the blogs:

1. go to http://gmodestmedblogs.blogspot.com/ to see them in reverse chronological order

2. click on 3 parallel lines top left, if you want to see blogs by category, then click on "labels" and choose a category​

3. or you can just click on the magnifying glass on top right, then  type in a name in the search box and get all the blogs with that name in them

please feel free to circulate this to others. also, if you send me their emails, i can add them to the list