Episode Details

Natural infection and / or vaccination? and Special report Mississippi

Uploaded 21-08-21

https://www.bbc.co.uk/news/health-58270098

Delta in UK

Viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK

https://www.ndm.ox.ac.uk/covid-19/covid-19-infection-survey/results/new-studies

https://www.ndm.ox.ac.uk/files/coronavirus/covid-19-infection-survey/finalfinalcombinedve20210816.pdf

Delta infections after two vaccine doses had similar peak levels of virus to those in unvaccinated people

Two doses of either vaccine, same level of protection against infection as natural infection

Natural infection followed by vaccination, even more protection than vaccination alone

After four to five months, effectiveness of these two vaccines similar

The time between doses does not affect effectiveness in preventing new infections

Now

Levels of immunity in the community

Implications for vaccination in children

Should we use virus or booster shots to top up immunity in adults?

Prof Eleanor Riley, immunologist, University of Edinburgh

We could be digging ourselves into a hole, for a very long time,

where we think we can only keep Covid away by boosting every year

Prof Adam Finn, government vaccine adviser

Over-vaccinating people when other parts of the world had none

a bit insane, it's not just inequitable, it's stupid

https://www.nature.com/articles/s41401-020-0485-4

SARS-CoV-2 belongs to the β coronavirus family

Seventh known coronavirus to infect humans

Four cause colds, 229E, NL63, OC43, and HKU1

SARS-CoV, 2002

MERS-CoV, 2012

SARS-CoV-2, 2019

SARS-CoV-2

Single-stranded RNA-enveloped virus

Entire genome, 29,881 bases

Encoding 9,860 amino acids

28 proteins essential for infection

Breadth of immunity

How much of the virus the immune system learns to attack

Natural infection, more polyclonal

Moderna or Pfizer or Oxford-AstraZeneca, just spike protein

Keeps people out of hospital

28 proteins recognised give Lymphocytes a ‘target rich environment’

Prof Eleanor Riley, immunologist, University of Edinburgh

That means if you had a real humdinger of an infection, you may have better immunity to any new variants that pop up as you have immunity to more than just spike

Strength of immunity

Power to prevent infection and cause severe disease

In the case of breakthrough infection or reinfection

Asymptomatic, low levels of antibodies

Symptomatic or ill, higher levels of antibodies

Duration of immunity

Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection

https://www.nature.com/articles/s41586-021-03696-9

Natural infection, no vaccination

Antibody to the receptor binding domain, active

RBD-specific memory B cells, active and relatively stable between 6 and 12 months after infection

Vaccination further increases all components of the humoral response

Results in serum neutralizing activities against variants of concern

Similar to or greater than the neutralizing activity against the original Wuhan Hu-1 strain

achieved by vaccination of naive individuals

The data suggest that immunity in convalescent individuals will be very long lasting and that convalescent individuals who receive available mRNA vaccines will produce antib