Coronavirus

Covid-19 daily cases started rising again about 4 weeks ago signaling the beginning of a fourth wave in the USA.   However, over the last week cases have resumed declining cutting short the fourth wave.   Is this a real indication of light at the end of the tunnel or are we just seeing the headlight of the oncoming train? 42.2% of the USA has been vaccinated with at least one shot to date (green part of the graph below).   This seems to be too low to meet the 70%+ threshold that is generally believed to be the vaccination level needed for herd immunity.   However, we have always asserted that while rigorous herd immunity with vaccines is the most desirable goal, effective human immunity may be reached earlier and allow the USA to flatten the COVID-19 infection curve.   Effective human immunity is a combination of natural immunity gained through infection by the SARS-COV-2 virus, vaccine immunity, and behavior immunity due to citizens rigorously practicing maski...

Covid-19 mRNA vaccines work very well in real life.   But as more data are analyzed it appears that certain groups of people such as seniors (65+) do not benefit as much from the vaccine.   We have been tracking the vaccine’s real-life efficacy through Florida’s Seniors First program to vaccinate everyone over 65 years old first.   As of April 19 th , 3.6M seniors or 80% have been vaccinated with 2.9M (64%) completing the two-dose regime.   The pace of senior vaccinations has slowed recently and this may be linked to the plateau and now rise in relative infection for seniors (see figure below).   There are several possible explanations for this observed phenomenon: 1.      Vaccine hesitancy expressed by 27% of Americans in recent polling,   Note that 80% of Florida seniors have already gotten their shot so polling answers may be more political posturing rather than reality.   Nevertheless, at some point before 100%, we will r...