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September 12, 2020

Vaccine Update - Halting One Trial

There are 3 vaccines that are in Phase 3 Trials in the US - each with a goal of enrolling 30,000 people - half to receive the vaccine and half to receive placebo.  They are vaccines from Moderna, Pfizer/BioNTech, and Oxford/ AstraZeneca.  No one will know what each person received until the end of the trial.  However there are independent Data and Safety Board Monitors and they can "unblind" the trial if there are problems. 

This week a person in the UK AstraZeneca trial developed a neurological problem and all of their trial sites were halted until the person can be fully evaluated to determine the cause.  They currently have trials in the UK, Brazil, South Africa and the US, although the trial in the US just started.  To date thousands of volunteers have received this vaccine in the UK.  In July they also briefly halted the trials and the volunteer was diagnosed with a previously unknown disease.  The safety considerations during vaccine development are paramount.  Yes, scientists want the vaccine to be efficacious, but safe.  Read more below.

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Moderna and Pfizer have each enrolled about 20,000 healthy volunteers to date - each person gets 2 doses (21 days apart -Pfizer- or 28 days apart- Moderna).  Subjects are followed and tested regularly for safety and efficacy and the followup continues even after the vaccine is approved. 

Clinical Trial Approval Process that all vaccines, drugs, and medical devices must conduct to apply for FDA approval. 

Phase 1 trials are small (ex 50 volunteers) - to test different doses and assess safety.

Phase 2 trials have hundreds of volunteers and safety is still being assessed.  Vaccine effectiveness and antibody production is being measured in randomly assigned vaccine and placebo groups.

Phase 3 trials have thousands of healthy volunteers, randomly assigned to vaccine or placebo groups. Safety is still assessed, while effectiveness is measured.

 


 

September 9, 2020

College Students Return to Campus and Covid-19

There are now thousands of new Covid-19 cases on college campuses as students and staff return for the Fall semester (estimate 51,000 yesterday). Many schools have been forced to close down and send students back home.  Students were tested on arrival and additional means to control the virus are being tried.

The University of Arizona tried a technique that was used previously in polio epidemics in the 1930 to identify community outbreaks.  A small sample of pooled waste water from sewage is one of the first ways to detect the virus in a community, as the virus is shed very early from the GI tract.  Students were all negative when they arrived on campus, but during the waste water testing process one dorm was positive.  All of the 311 students were tested by molecular testing and 2 of the students were positive and could be isolated.  A recent update showed that a total of 46 students were now positive, among 10,000 antigen tests  Hopefully this is a manageable number for tracking and isolation and the campus can stay open. 

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Other schools have set up twice weekly wastewater surveys, including Syracuse, Univ. of California San Diego, and Rensselaer Polytechnic Institute according to the press report  and can identify and quarantine positive students - keeping everyone on campus.  This is a good strategy for detecting small outbreaks and containing them on campus.  

 <https://www.washingtonpost.com/nation/2020/08/28/arizona-coronavirus-wastewater-testing/>

September 5, 2020

Testing for Antibodies in Covid-19 Patients

There are many types of antibody tests available, each using one of 3 different methods.  They can measure 2 different types of antibodies:  Immunoglobulin M (IgM), which usually appears first, and /or Immunoglobulin G (IgG) which usually doesn't appear until after 2 weeks.  The Infectious Disease Society of America expert panel currently recommends testing sometime between the 3rd and 4th week after symptoms develop in patients in which this information is important.  It is most helpful in symptomatic patients whose SARS-CoV-2 virus test is negative. 

But these antibody tests are not routinely recommended for an individual patient, because the presence of antibodies doesn't mean that they are immune and may give a false sense of security.  These serologic tests are most useful when screening large populations of people in order to assess the prevalence of past infections by region. Continue Reading

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I live in New York City and results of 1.5 million antibody tests were recently released from the Dept of Health.  Antibody tests for Covid-19 were positive in more than 27% of NYC residents, and the numbers varied by zip codes, and boroughs.  In one zipcode more than 50% of the antibody  tests were positive, demonstrating a high incidence of Covid-19 at some time during the Spring or Summer. 

September 2, 2020

Another Point of Care Covid-19 Antigen Test

Is it a game changer?  Maybe slightly.  Abbott's BivaxNOW Covid-19 Antigen Card is like a pregnancy test, takes only 15 minutes, and only costs $5.  A nasal swab sample is applied to a card and when the Sars-CoV-19-nucleoside antibody on the card detects the virus a pink line forms below the positive control line.  The square with the arrow on the card is where this happy patient's sample reads negative.

But the test, which does not require a machine to read the result, still needs to be performed in a doctors office, clinic, or other health care facility.  In addition the test has to be performed within 7 days of the onset of symptoms making this a diagnostic test, not a surveillance test for public health detection. 

Last week the FDA gave an Emergency Use Approval (EUA) based on only 102 samples tested.  The sensitivity and specificity which were excellent were thus determined on a very small patient group. The results are saved in a free app on the patient's phone and can provide an ongoing record of test results.  But will they be also be reported to the Dept. of Health?   This Abbott BivaxNOW test will now be scaled up this month - millions of the tests have been purchased by the US Government.   Continue Reading Below

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Dr. Michael Mina an epidemiologist/scientist from Harvard, advocates for a simple public health test based on the same principle, i.e. like a home pregnancy test, but the FDA hasn't yet approved "at home tests." I've discussed the "Rapid At Home Test" previously, and I'm hoping that the Abbott approval may be an early indication that the "at home tests" may also soon be approved.  When it is available, it will allow people to do frequent tests on themselves and their family.  If they are infectious (and not symptomatic) they can stay home when the test is positive.  There is a good correlation between the period of viral shedding and the test turning positive within 1-2 days.  If this test is approved, it will be a better way to control the pandemic. 

 

 

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