Antibody test accuracy and immunity passports


Distinguished Member
Some virologists responding to the headlines in UK press on Monday...



Well-known Member
Few things re above that I wanted to point out in another thread but thought contents of the linked documents were self explanatory.

  • The headlines on both Imperial and King's college press release on their home page are accurate but BBC's reporting on Imperial's is misleading ie "Antibodies fall rapidly after infection".
  • Imperial study is like "prevalence" of antibody in population at the time of testing. They tested different sets of population/group and found decline in positivity% of prevalence among general populace.
  • It is not that antibodies level fell rapidly for 27% of people from first group in 3 months. Those first group were not followed up in Imperial's study. If they do similar test now, the antibody prevalence% could be higher or at least similar ie 6%. Possible that it correlates strongly with prevalence of virus. Yes these has been accounted for and prevalence on Sep was higher than in June but just to make my point little clearer.
  • King's college study is different to Imperial in that they actually followed up n=65 patients over course of time. Similar study on Follow up to Mt Sinai was published yesterday. Mt Sinai paper has some interesting info there and it's also not very long.
  • Short Summary from Kings and Sinai: Antibody response is no different than any other acute viral infection at least for the period up to 5 months covered by these scientific papers. Most people infected with SARS2 produces antibodies but for some unkown reasons, the level produced seems directly proportional to the severity of disease. Also these initial level seems to correlate with longevity. They observed short drop initially but still was robust in 3 and 5 months endpoints for most study subjects. At this time nobody knows the base level needed to prevent reinfection.
  • One of the most interesting observation noted on Mt Sinai paper :
    The initial serum antibody titer was likely produced by plasmablasts, and plasmablast-derived antibody peaks 2 to 3 weeks post symptom onset. Given an IgG half-life of approximately 21 days, the sustained antibody titers observed here over time are likely produced by long-lived plasma cells in the bone marrow.
  • B Cells activation and protection is not proven yet for SARS Cov2. For Human coronavirus, reinfection was observed when challenged after 1 year among those who had undetectable antibody titer. B cells in these instances seems to be doing nothing. SARS Cov2 is showing similar traits to seasonal HCovs but could be different in this regard.
  • Last 2 were also mentioned on Imperial paper. Despite different methodologies, conclusion on all 3 papers are same - antibodies level declines over time and increases risk of reinfection.


If anyone is having an antibody test and is booking it on the Gov website then I recommend you ring them up once you get an email/text with a code and give them the code over the phone.

A number of staff from where my wife works have had the code fail after clicking the link on the email/text and have been told to fill out the form again and ring them up with the code instead.


Distinguished Member
Another study, from Oxford University Hospitals, showing that of those healthcare workers who had the misfortune to catch COVID-19 at the start of pandemic 99% thankfully remain immune to reinfection over 6 months later.



Distinguished Member
Vaccine passports

Proving you have had a coronavirus vaccine will make it easier to do things and help unlock the economy, the PM says.

is that the closest we have come to a confirmation of some description that a vaccine passport is in the making? Todays announcement has set out that there will be a specific task force put in place regarding international travel and further announcements will come in April. I have a feeling that will entail a passport of some description....


Distinguished Member
it makes sense, certainly for international travel at least, other countries will want guarantees of protection.

We could be at a point in a few months where instead of countries locking out other countries due to high covid, they would instead allow only certain countries where vaccinations are high and people have proof of being vaccinated/negative test. So the UK could be one of the first to be allowed free travel and such in that case.


Well-known Member
Grand. The more encouragement we have for vaccination, the better.

If they have any sense we will combine it with the international vaccination documentation. Then maybe we can have the start of a global system that helps us against future pandemics/severe localised infections.


I called it a long time back, always felt like it was a step we were going to take. Even back then.

Not just for foreign travel either.

I've tried telling people on reddit that there was a decent possibility that we might end up with domestic passports as well as ones for trips abroad. Or at the very minimum the government would look into it. Only to be down voted into oblivion.

Reading through everything that's been announced today it looks like they are firmly counting on the vaccine rollout to get us out of this mess.

Getting as many people to have those shots as possible is the only way it will work.

If enough of the younger population won't get vaccinated get prepared to need a smart phone app showing your vaccination status to goto the cinema. It'll happen if needed.

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