Paper and Threads

Viruses don't go away without vaccines. Measles, a highly contagious virus, was eradicated with vaccination, but occasionally pockets of infection do erupt in susceptible groups who refuse to be vaccinated.

Herd Immunity was recognized in the early 1900s, first by veterinarians, and then in humans.  When a high enough percentage of individuals in a community are exposed to a virus, the rate of transmission and infection slows down because there aren't enough susceptible people to pass along the virus.  Herd immunity needs approximately 70% of a community to either have been infected or vaccinated. 

The vaccines in the US must be at least 50% effective in order to get FDA approval.  If 100 patients are vaccinated 50 of them would develop immunity and protection.  If many patients don't accept vaccination, we can do another calculation:  If 100 people are offered a vaccine, and only 60% get vaccinated, and only 50% of them develop a strong immune response, only 30 patients of the original 100 patients would be counted in the development of herd immunity.  READ BELOW

Dr.Tony Fauci, from NIAID/NIH, estimates that only 10% of the population in the US was infected so far.  Therefore vaccination is extremely important in the development of herd immunity to Covid-19.   

Bottom Line:  Develop a very safe vaccine, with high effectiveness (preferably 70%), and vaccinate as many people as possible.  Only then will our lives return to pre-pandemic freedom.  But we would still need to follow the Public Health Guidelines to control breakouts. 

Posted by Shirley at 7:04 AM | Permalink | Comments (0)

New York City now has some charming outdoor restaurants on the sidewalk or street in front of their buildings.  This weekend people will be able to also eat inside these restaurants, which are limited to 25% occupancy.   In order to protect restaurant clients, temperature checks were recommended on each customer at the door. 

There have been recent articles and preliminary studies demonstrating that asymptomatic Covid-19 patients don't have fevers, but do have the same viral load in their noses, pharynx, and lungs as sick patients.  In several studies 30-40% of patients with positive virus tests are asymptomatic and don't have fevers.  These are the virus spreaders.  Therefore personal distancing and other possible public health measures are still recommended when congregating - social distance when possible, in good ventilation, and limit time spent when congregating inside.     

Posted by Shirley at 7:16 AM | Permalink | Comments (0)

This week Johnson and Johnson began their Phase 3 vaccine trial in 60,000 volunteers.- joining the other 2 vaccines (Moderna, Pfizer).  It is a "viral vector" vaccine in which the gene for the SARS-CoV-2 virus spike is attached to an adenovirus which carries the gene into cells.  The gene then directs the cells to synthesize the coronavirus spike protein which stimulates an immune response in the volunteer.  This is a vaccine technique that J and J has used to make other vaccines, and their Ebola vaccine was approved this year in the UK.  The vaccine produced good antibody responses and there were minimal side effects in their phase 1/2 coronavirus  trial in almost 400 volunteers.  Only a single dose is needed and the vaccine is refrigerated, not frozen.  These are two major advantages of this vaccine. 

The vaccine protected Rhesus Macaque monkeys in a preclinical challenge trial - when they were vaccinated and then given the virus. 

Posted by Shirley at 6:30 AM | Permalink | Comments (1)

Within the last weeks Covid-19 reinfections were reported in 4 patients, separated in time from their first episode.  Sometimes patients continue to have a positive molecular virus test after their Covid-19 infection, but the PCR test is able to measure remaining dead virus after recovery. RNA viruses mutate slowly, usually in unimportant portions of the virus.  The ability to sequence the RNA allows scientists to detect mutations - and that is how they determined that NYC was infected with a European strain of SARS-CoV-2, not the Wuhan strain.  The European strain was infecting communities in NYC long before there was any control of the planes arriving from Europe or even China. 

I was surprised that in the 4 patients with recurrent disease (one each from China, Belgium, Netherlands, and Nevada), scientists were able to compare the SARS-CoV-2 virus that was isolated from both their first and second positive SARS-CoV-2 virus samples.  There were different mutations present when the rwo samples were compared, thus demonstrating that these were 2 separate infections in each patient.  It is not clear how many cases of reinfection will be reported, virus samples from each episode must be available for testing.  These cases were each reported online, not in published scientific papers that I could find. 

Posted by Shirley at 7:12 AM | Permalink | Comments (1)

These are patients who have continuing symptoms for 4 or more weeks after Covid-19.  Symptoms can last more than 4 weeks after mild cases of Covid-19, and more than 8 weeks after hospitalized cases.  Unfortunately symptoms can last for months.  Many of the current long haul patients couldn't get a virus test when they first became ill because of the restrictions on testing.  But many of them now have positive antibody tests documenting the virus. 

Symptoms are very variable among patients, and in general they haven't returned to their pre-infection status.  There are respiratory symptoms, cardiac symptoms, decreased taste/smell, myalgias, headache, sleep problems, clotting disturbances, skin rashes, foggy brain, and fatigue mirroring chronic fatigue syndrome.  Although there are theories about the cause including continued infection or immune response to the virus and/or virus debris, the cause is unknown.  The incidence is greater than has been seen with other viral infections, and specialized centers are being developed to assess these patients and test therapies.  Long hauler patients are advised to locate one of these centers.

Posted by Shirley at 6:29 AM | Permalink | Comments (1)