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Johnson & Johnson single-shot Janssen vaccine
J&J's press release says
Quote: Wrote:Vaccine Candidate 72% Effective in the US and 66% Effective Overall at Preventing Moderate to Severe COVID-19, 28 Days after Vaccination

85% Effective Overall in Preventing Severe Disease and Demonstrated Complete Protection Against COVID-19 related Hospitalization and Death as of Day 28

The topline safety and efficacy data are based on 43,783 participants accruing 468 symptomatic cases of COVID-19.
The level of protection against moderate to severe COVID-19 infection was 72% in the United States, 66% in Latin America and 57% in South Africa, 28 days post-vaccination.

There was a clear effect of the vaccine on COVID-19 cases requiring medical intervention (hospitalization, ICU admission, mechanical ventilation, extracorporeal membrane oxygenation (ECMO), with no reported cases among participants who had received the Janssen COVID-19 vaccine, 28 days post-vaccination.

Efficacy against severe disease increased over time with no cases in vaccinated participants reported after day 49.

The B.1.351 lineage also known as 501Y.V2 variant and 20H/501Y.V2 (formerly 20C/501Y.V2) is a variant of SARS-CoV-2,

Study: NCT04505722.  18+ yo., not pregnant.   It began Sep. 7.  I don't see a date when they took a snapshot of the results that they announced.  Perhaps it was about 10 days ago, January 19, so I'll use that for a date.

Original primary outcome was number with COVID 14 days after vaccination.  During the study another primary outcome was added for the number with COVID 28 days after vaccination.

It appears the study accepted subjects from about Sep. 7, ending before Jan 25.

The good news and the bad news is that it has been tested against the South African variant. 

On the face of it, it appears that this vaccine is 7x (38% vs 5%) less effective than the Pfizer & Moderna for the disease spreading in the US.  It will be less effective at reducing the spread of the disease per vaccine given.   (If you gave 100K doses of Moderna or Pfizer in a general population where 10% were getting COVID, only 500 of the 100K would get COVID.  With this vaccine, 3800 would get COVID.  Without the vaccine, 100K would get sick. ***)

However, it is the long term damage or death that is the big concern for COVID.  Thus their claim that no one past 49 days has had a severe disease is  worth looking at closely.  A subject who was given the vaccine on the first day of the study (Sep. 7) would reach 28 days on Oct 5 and the 49th day at Oct. 26.  They indicate he would not have had a severe disease after 49 days.  Subjects vaccinated after about December 1 would not have reached 49 days when they took this snapshot of results.

*** I don't like this linear efficacy measure of the vaccine.  To my way of thinking, I'd like to see the effect of the vaccine on R.

The South African variant S.501Y.V2  was first detected in samples from October 5, where it quickly dominated all the other variants.  In 7 weeks, it was responsible for 90% of the cases.
[Image: South-African-Genomes.png]

It is difficult to figure out the efficacy of the vaccine against the South African variant without knowing the timeline of the start of subjects in South Africa.

For the people vaccinated, much of the advantage of a single dose is lost by this vaccine's 28-days judgement of effectiveness.  It doesn't seem to be effective sooner, so I'd go with higher effectiveness.

For the government (who is paying for the vaccine), there may be an advantage (depending on the cost of the vaccine & cost to administer it) to having a single dose.  The government should also weigh the cost of the difference in the number of people who get sick.   (If there are 250M people in the US, and some 50M have had COVID already, then there are 200M people yet to be infected.  With Pfizer/Moderna, 10M would be infected.  With the J&J vaccine, 76M would get infected.)

As a 65+ year old, I would MUCH prefer the 95% effective vaccines.  For younger people who have less risk, it will matter less.

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Johnson & Johnson single-shot Janssen vaccine - by M_T - 01-30-2021, 04:38 AM

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