Herd Immunity is Important
Herd immunity has to work if the vaccine works due to the simple mechanism that the number of susceptible individuals goes down.
Michelle, a friend, had a genetic deficiency. Her doctor says she should not risk the vaccine. She is a certified nurse, and her hospital fired her for refusing. This is not that uncommon. There are some people with good and valid reasons not to be vaccinated. That's why herd immunity is important. You can never vaccinate everyone, and SARS-COVID-2 has a reservoir of infection in animals that never get vaccinated.
The formula for herd immunity is V = 1-1/(R0), where V is the required level of herd immunity given R0, the spread rate. According to most sources, R0 for the Delta variant is 5, twice as high as for the Alpha variant. So V is .8 or 80%. That is pretty high, but not a high as mumps, with an R0 of 10.
Also, people who have recovered fro COVID have lasting immunity, including from delta. There are perhaps 100 million in the US with natural immunity. Add this to the 150 million who have had the vaccines.
The unvaccinated are at risk, but COVID is treatable. It should rarely require hospitalization. Johns Hopkins and University of Texas are publishing lists of treatments that work. This is a void in the system right now.
Caution is useful. Panic is irresponsible. I got my shots. Talk to your doctor.
https://covid.cdc.gov/covid-data-tracker/#datatracker-home
https://covid.cdc.gov/covid-data-tracker/#trends_da
No comments:
Post a Comment