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Breakthrough Covid-19 Infections After Vaccination

Although both Moderna and Pfizer vaccines both had efficacy of 94-95% in their clinical trials, people aren't protected fully until at least 2 weeks after their 2nd vaccine dose.  Now we are getting reports of the vaccine performance in the real world in millions of patients.  In California (UC LosAngeles and UC SanDiego) and Texas (Univ of Texas Southwestern Medical Center) health care workers were vaccinated and then tested regularly to detect Covid-19.  The number of cases decreased beginning 2 weeks after the first dose and most importantly maximal protection occurred at 2 weeks after the second dose.  

The incidence was reduced to 0.05% (of approximately 10,000 HCW) in both studies and with both vaccines.  There is a 3rd recent report from Hadassah Medical Center in Jerusalem with similar results with the Pfizer vaccine,  and at that time the B.1.1.7 variant (UK) was 80% of infections locally.  Read More Below


Breakthrough cases can occur in people who have an immune deficiency disorder or because their bodies cannot produce a robust immune reaction, which can be seen in elderly patients.  Examination of virus samples from breakthrough patients will give us information about the current vaccines ability to prevent infection with the new variants.  In order to analyze that data virus samples need to be saved for genomic sequencing, a complex process.   There is no current evidence that the breakthrough cases are due to the circulating variants, but the CDC has ramped up genomic testing of coronavirus patient samples to map the spread of the variants and especially those in breakthrough cases.

I've been following the SARS-CoV-2 variants present locally.  This week, ending March 23rd, a subset of 1481 patient samples from the NYC Health and Hospital facilities (inpatients and outpatients)  were analyzed in the NYC Pandemic Response Lab.  Variants present included UK Variant (141), California variants (15), Brazilian variant (1) and New York City variant (481).  There were no S. African variants detected.  I hope this information will be helpful for my friends that live in this area.  I'm still following the CDC mitigation guidelines for vaccinated people. 

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