Covid-19, Spanish Flu, Smallpox, And Harvard -- December 25, 2021

Smallpox: eradicated by herd immunity? USA Today.

Because immunity varies with age and not everyone can get vaccinated — such as those who are immunocompromised, have specific allergies or pregnant women with certain types of vaccines — herd immunity is a crucial protective phenomenon. To establish it, one important factor is the number of immunized people within a population has to be at a certain percentage or threshold. According to the WHO, this figure was eight out of every 10 people for smallpox, based on its early eradication effort.

And because pathogens are not confined by geographical borders, this 80% immunization or higher is not a threshold restricted to one population — it has to be shared by all, whether at a local, national or global level. This means if any populations have vaccination rates below the threshold, there is a great risk for disease transmission to other unvaccinated or vulnerable individuals, even in populations with adequate herd immunity, such as in the case with measles outbreaks in recent years.

For smallpox, this homogeneity in vaccination rates across varying populations was only successfully achieved with mass smallpox vaccination, as claimed by the Facebook post.

A second important determinant for herd immunity is how long biological immunity against a pathogen lasts. While immunological memory forms with every new infectious encounter, this can fade over time, which is why booster shots are typically given. Smallpox immunity unfortunately does decline — after five to 10 years — but it is believed vaccinated individuals still have some protection against fatal outcomes should an outbreak, in the very rare event, reappear.

Routine smallpox vaccination in the U.S. was stopped in 1972, after it was declared eradicated. The CDC only recommends the vaccine to lab workers who work with smallpox or smallpox-like viruses, and to those who need long-term protection like military personnel. 

That's probably as good a summary I've seen in mainstream media. Which raises two questions:

• did the world really get to 80% vaccinated; and,
• if so, how did they ever do it, 80%?

Ivory Tower: associate professor epidemiology of Yale School of Public Health, a 2018 MacArthur Fellow,  --

• says Biden is failing on Covid-19;
• president updated the nation on December 21, 2021:
• The president was eager to point out that under his watch, 200 million people were fully vaccinated
  except we know now (20-20 hindsight, and still conjecture) that we require boosters to protect against omicron and only about 60 million Americans have had that additional jab
• We already know vaccines alone will not solve this problem (go back and read the USA Today article today regarding smallpox)
• Public health experts called for more emphasis on a wider range of interventions, including rapid testing, masking and environmental controls, such as the upgrading of ventilation systems in buildings across the country (upgrading ventilation systems in buildings across the nation: incredibly naive; not actionable; and would take decades). Yet such measures remain underutilized here in the United States
• associate professor thrilled with additional testing (to what end?)
• CDC recommended policy for schools: "test and stay"
• professor says the infrastructure and resources to carry out that strategy simply not there for many school districts (to "test and stay"? what infrastructure is required? Our Texas school has that policy)
• professor says masks work but we need to use N95 masks, not the ones most Americans are using (any data to support that? I doubt it.)
• simply fades away at the end
• Smallpox was a much worse disease than Covid-19, and nothing was done except the vaccine: no social distancing, no global lock downs, no masks.